WO2021226369A1

WO2021226369A1 - Enzymes with ruvc domains

Info

Publication number: WO2021226369A1
Application number: PCT/US2021/031143
Authority: WO
Inventors: Brian Thomas; Christopher Brown; Rose KANTOR; Audra DEVOTO; Cristina Butterfield; Lisa ALEXANDER; Daniela S.A. Goltsman; Jason Liu; Rebecca LAMOTHE; Diego Espinosa; Meghan STORLIE; Greg COST
Original assignee: Metagenomi Ip Technologies, Llc
Priority date: 2020-05-08
Filing date: 2021-05-06
Publication date: 2021-11-11
Also published as: EP4165177A1

Abstract

The present disclosure provides for endonuclease enzymes having distinguishing domain features, as well as methods of using such enzymes or variants thereof.

Description

ENZYMES WITH RUVC DOMAINS

RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/022,321, filed on May 8, 2020, entitled “ENZYMES WITH RUVC DOMAINS”, U.S. Provisional Application No. 63/032,465, filed May 29, 2020, entitled “ENZYMES WITH RUVC DOMAINS”, and U.S. Provisional Application No. 63/116,156, filed November 19, 2020, entitled “ENZYMES WITH RUVC DOMAINS”, and U.S. Provisional Application No. 63/180,587, filed on April 27, 2021, entitled “ENZYMES WITH RUVC DOMAINS”, each of which are entirely incorporated herein by reference.

BACKGROUND

[0002] Cas enzymes along with their associated Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) guide ribonucleic acids (RNAs) appear to be a pervasive (-45% of bacteria, -84% of archaea) component of prokaryotic immune systems, serving to protect such microorganisms against non-self nucleic acids, such as infectious viruses and plasmids by CRISPR-RNA guided nucleic acid cleavage. While the deoxyribonucleic acid (DNA) elements encoding CRISPR RNA elements may be relatively conserved in structure and length, their CRISPR-associated (Cas) proteins are highly diverse, containing a wide variety of nucleic acid interacting domains. While CRISPR DNA elements have been observed as early as 1987, the programmable endonuclease cleavage ability of CRISPR/Cas complexes has only been recognized relatively recently, leading to the use of recombinant CRISPR/Cas systems in diverse DNA manipulation and gene editing applications.

SEQUENCE LISTING

[0003] The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on May 6, 2020, is named 55921_713_601_SL.txt and is 828,807 bytes in size.

SUMMARY

[0004] In some aspects, the present disclosure provides for an engineered nuclease system comprising: (a) an endonuclease comprising a RuvC III domain and an HNH domain, wherein the endonuclease is derived from an uncultivated microorganism, and wherein the endonuclease is a class 2, type II Cas endonuclease; and (b) an engineered guide ribonucleic acid structure configured to form a complex with the endonuclease comprising: (i) a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and (ii) a tracr ribonucleic acid sequence configured to bind to the endonuclease. In some embodiments, the RuvC III domain comprises a sequence with at least 70%, at least 75%, at least 80% or at least 90% sequence identity to any one of SEQ ID NOs: 45-88 or SEQ ID NOs: 246-262. In some aspects, the present disclosure provides for an engineered nuclease system comprising: (a) an endonuclease comprising a RuvC III domain having at least 75% sequence identity to any one of SEQ ID NOs: 45-88 or SEQ ID NOs: 246-262; and (b) an engineered guide ribonucleic acid structure configured to form a complex with the endonuclease comprising: (i) a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and (ii) a tracr ribonucleic acid sequence configured to bind to the endonuclease. In some aspects, the present disclosure provides for an engineered nuclease system comprising: (a) an endonuclease configured to bind to a protospacer adjacent motif (PAM) sequence comprising SEQ ID NOs: 149-158 or 294-296, wherein the endonuclease is a class 2, type II Cas endonuclease; and (b) an engineered guide ribonucleic acid structure configured to form a complex with the endonuclease comprising: (i) a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and (ii) a tracr ribonucleic acid sequence configured to bind to the endonuclease. In some embodiments, the endonuclease is not a Cas9 endonuclease, a Cas 14 endonuclease, a Cas 12a endonuclease, a Cas 12b endonuclease, a Cas 12c endonuclease, a Cas 12d endonuclease, a Casl2e endonuclease, a Casl3a endonuclease, a Cas 13b endonuclease, a Cas 13c endonuclease, or a Cas 13d endonuclease. In some embodiments, the endonuclease has less than 80% identity to a Cas9 endonuclease. In some embodiments, the endonuclease further comprises an HNH domain. In some embodiments, the tracr ribonucleic acid sequence comprises a sequence with at least 80% sequence identity to about 60 to 90 consecutive nucleotides selected from any one of SEQ ID NOs: 138-148 or SEQ ID NO: 280. In some aspects, the present disclosure provides for an engineered nuclease system comprising, (a) an engineered guide ribonucleic acid structure comprising: a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and a tracr ribonucleic acid sequence configured to bind to an endonuclease, wherein the tracr ribonucleic acid sequence comprises a sequence with at least 80% sequence identity to about 60 to 90 consecutive nucleotides selected from any one of SEQ ID NOs: 138-148 or SEQ ID NO: 280; and (b) a class 2, type II Cas endonuclease configured to bind to the engineered guide ribonucleic acid. In some embodiments, the endonuclease is configured to bind to a protospacer adjacent motif (PAM) sequence selected from the group comprising SEQ ID NOs: 149-158 or 294-296. In some embodiments, the engineered guide ribonucleic acid structure comprises at least two ribonucleic acid polynucleotides. In some embodiments, the engineered guide ribonucleic acid structure comprises one ribonucleic acid polynucleotide comprising the guide ribonucleic acid sequence and the tracr ribonucleic acid sequence. In some embodiments, the guide ribonucleic acid sequence is complementary to a prokaryotic, bacterial, eukaryotic, fungal, plant, mammalian, or human genomic sequence. In some embodiments, the guide ribonucleic acid sequence is 15-23 nucleotides in length. In some embodiments, the endonuclease comprises one or more nuclear localization sequences (NLSs) proximal to an N- or C-terminus of the endonuclease. In some embodiments, the NLS comprises a sequence selected from the group consisting of SEQ ID NO: 180-195. In some embodiments, the engineered nuclease system further comprises a single- or double-stranded DNA repair template comprising from 5' to 3': a first homology arm comprising a sequence of at least 20 nucleotides 5' to the target deoxyribonucleic acid sequence, a synthetic DNA sequence of at least 10 nucleotides, and a second homology arm comprising a sequence of at least 20 nucleotides 3' to the target sequence. In some embodiments, the first or second homology arm comprises a sequence of at least 40, 80, 120, 150, 200, 300, 500, or 1,000 nucleotides. In some embodiments, the system further comprises a source of Mg²⁺ In some embodiments, the endonuclease and the tracr ribonucleic acid sequence are derived from distinct bacterial species within a same phylum. In some embodiments, the endonuclease is derived from a bacterium belonging to genus Dermabacter.

In some embodiments, the endonuclease is derived from a bacterium belonging to Phylum Verrucomicrobia, Phylum Candidatus Peregrinibacteria, or Phylum Candidatus Melainabacteria. In some embodiments, the HNH domain comprises a sequence with at least 70% or at least 80% identity to any one of SEQ ID NOs: 89-132 or SEQ ID NOs: 263-279. In some embodiments, the endonuclease comprises SEQ ID NOs: 1-44 or SEQ ID NOs: 229-245, or SEQ ID NOs: 292- 293 or a variant thereof having at least 55% identity thereto. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 46 or SEQ ID NOs: 46-47. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 90 or SEQ ID NOs: 90-91. In some embodiments, the endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NOs: 214-221. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 2 or SEQ ID NOs: 2-3. In some embodiments, the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 138 or SEQ ID NO: 133. In some embodiments, the guide RNA structure comprises a tracr ribonucleic acid sequence comprising a hairpin comprising at least 8, at least 10, or at least 12 base-paired ribonucleotides. In some embodiments, the endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 149 and SEQ ID NO: 154. In some embodiments: (a) the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 46; (b) the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 133 or SEQ ID NO: 138; and (c) the endonuclease is configured to bind to a PAM comprising SEQ ID NO: 149 or SEQ ID NO: 154. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 48 or SEQ ID NOs: 48-71. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 92 or SEQ ID NOs: 92-115. In some embodiments, the endonuclease comprises SEQ ID NO: 222. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 4 or SEQ ID NOs: 4-27. In some embodiments, the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 139, SEQ ID NOs: 139-143, or SEQ ID NO:

134. In some embodiments, the endonuclease is configured to bind to a PAM comprising SEQ ID NO: 150 or SEQ ID NO: 155. In some embodiments: (a) the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 48; (b) the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 134 or SEQ ID NO: 139; and (c) the endonuclease is configured to bind to a PAM comprising SEQ ID NO: 150 or SEQ ID NO: 155. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 72, SEQ ID NOs: 72-83, and SEQ ID NOs: 246-253. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 116, SEQ ID NOs: 116-127, and SEQ ID NOs: 263-270. In some embodiments, the endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NO: 223-225. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 28, SEQ ID NOs: 28-39, and SEQ ID NOs: 229-236. In some embodiments, the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 144, SEQ ID NOs: 144-146, and SEQ ID NO: 135. In some embodiments, the endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 151 and SEQ ID NO: 156. In some embodiments: (a) the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 72; (b) the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 135 or SEQ ID NO: 144; and (c) the endonuclease is configured to bind to a PAM comprising SEQ ID NO: 151 or SEQ ID NO: 156. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 84, SEQ ID NOs: 84- 86, and SEQ ID NOs: 254-262. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 128, SEQ ID NOs: 128-130, and SEQ ID NOs: 271-279. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 40, SEQ ID NOs: 40-42, and SEQ ID NOs: 237-245. In some embodiments, the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 147, SEQ ID NO: 280, or SEQ ID NO: 136. In some embodiments, the endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 152 and SEQ ID NO: 157. In some embodiments: (a) the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 84; (b) the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 136 or SEQ ID NO: 147; and (c) the endonuclease is configured to bind to a PAM comprising SEQ ID NO: 152 or SEQ ID NO: 157. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 87, or SEQ ID NOs: 87-88. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 131 or SEQ ID NOs: 131-132. In some embodiments, the endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NO: 226- 228. In some embodiments, the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 43 or SEQ ID NOs: 43-44. In some embodiments, the guide RNA structure comprises a tracr ribonucleic acid sequence comprising at least two hairpins comprising less than 5 base-paired ribonucleotides. In some embodiments, the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 148 or SEQ ID NO: 137. In some embodiments, the endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 153 and SEQ ID NO: 158. In some embodiments: (a) the endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 87; (b) the guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 137 or SEQ ID NO: 148; and (c) the endonuclease is configured to bind to a PAM comprising SEQ ID NO: 153 or SEQ ID NO: 158. In some embodiments, the sequence identity is determined by a BLASTP, CLUSTALW, MUSCLE, MAFFT, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. In some embodiments, the sequence identity is determined by the BLASTP homology search algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

[0005] In some aspects, the present disclosure provides for an engineered guide ribonucleic acid polynucleotide comprising: (a) a DNA-targeting segment comprising a nucleotide sequence that is complementary to a target sequence in a target DNA molecule; and (b) a protein-binding segment comprising two complementary stretches of nucleotides that hybridize to form a double-stranded RNA (dsRNA) duplex, wherein the two complementary stretches of nucleotides are covalently linked to one another with intervening nucleotides, and wherein the engineered guide ribonucleic acid polynucleotide is capable of forming a complex with an endonuclease comprising a RuvC III domain having at least 75% sequence identity to any one of SEQ ID NOs: 45-88 or SEQ ID NOs: 246-262 and targeting the complex to the target sequence of the target DNA molecule. In some embodiments, the DNA-targeting segment is positioned 5' of both of the two complementary stretches of nucleotides. In some embodiments: (a) the protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 138; (b) the protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 139 or SEQ ID NOs: 139-143; (c) the protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 144 or SEQ ID NOs: 144-146; (d) the protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 147; or (e) the protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 148. In some embodiments: (a) the guide ribonucleic acid polynucleotide comprises a tracr ribonucleic acid comprising a hairpin comprising at least 8, at least 10, or at least 12 base-paired ribonucleotides; or (b) the guide ribonucleic acid polynucleotide comprises a tracr ribonucleic acid sequence comprising at least two hairpins comprising less than 5 base- paired ribonucleotides.

[0006] In some aspects, the present disclosure provides for a deoxyribonucleic acid polynucleotide encoding the engineered guide ribonucleic acid polynucleotide described above. [0007] In some aspects, the present disclosure provides for a nucleic acid comprising an engineered nucleic acid sequence optimized for expression in an organism, wherein the nucleic acid encodes an endonuclease comprising a RuvC III domain and an HNH domain, wherein the endonuclease is a class 2, type II Cas endonuclease, and wherein the endonuclease is derived from an uncultivated microorganism.

[0008] In some aspects, the present disclosure provides for a nucleic acid comprising an engineered nucleic acid sequence optimized for expression in an organism, wherein the nucleic acid encodes an endonuclease comprising a RuvC III domain having at least 70% sequence identity to any one of SEQ ID NOs: 45-88. In some embodiments, the endonuclease comprises an HNH domain having at least 70% or at least 80% sequence identity to any one of SEQ ID NOs: 89-132. In some embodiments, the endonuclease comprises SEQ ID NOs: 170-179 or a variant thereof having at least 70% sequence identity thereto. In some embodiments, the endonuclease comprises a sequence encoding one or more nuclear localization sequences (NLSs) proximal to an N- or C-terminus of the endonuclease. In some embodiments, the NLS comprises a sequence selected from SEQ ID NOs: 180-195. In some embodiments, the organism is prokaryotic, bacterial, eukaryotic, fungal, plant, mammalian, rodent, or human. In some embodiments, the organism is E. coli , and: (a) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 170; (b) the nucleic acid sequence has at least 70%, 80%, or 90% identity to a sequence selected from the group consisting of SEQ ID NOs: 171-172; (c) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 173; (d) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 174; or (e) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 175. In some embodiments, the organism is human, and: (a) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 176; (b) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 177; (c) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 178; or (d) the nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 179.

[0009] In some aspects, the present disclosure provides for a vector comprising a nucleic acid sequence encoding a class 2, type II Cas endonuclease comprising a RuvC III domain and an HNH domain, wherein the endonuclease is derived from an uncultivated microorganism. [0010] In some aspects, the present disclosure provides for a vector comprising any of the nucleic acids described herein. In some embodiments, the nucleic acid further comprises a nucleic acid encoding an engineered guide ribonucleic acid structure configured to form a complex with the endonuclease comprising: (a) a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and (b) a tracr ribonucleic acid sequence configured to bind to the endonuclease. In some embodiments, the vector is a plasmid, a minicircle, a CELiD, an adeno-associated virus (AAV) derived virion, or a lentivirus.

[0011] In some aspects, the present disclosure provides for a cell comprising any of the vectors described herein.

[0012] In some aspects, the present disclosure provides for a method of manufacturing an endonuclease, comprising cultivating any of the cells described herein.

[0013] In some aspects, the present disclosure provides for a method for binding, cleaving, marking, or modifying a double-stranded deoxyribonucleic acid polynucleotide, comprising: (a) contacting the double-stranded deoxyribonucleic acid polynucleotide with a class 2, type II Cas endonuclease in complex with an engineered guide ribonucleic acid structure configured to bind to the endonuclease and the double-stranded deoxyribonucleic acid polynucleotide; wherein the double-stranded deoxyribonucleic acid polynucleotide comprises a protospacer adjacent motif (PAM); and wherein the PAM comprises a sequence selected from the group consisting of SEQ ID NOs: 149-153 or SEQ ID NOs: 154-158. In some embodiments, the double-stranded deoxyribonucleic acid polynucleotide comprises a first strand comprising a sequence complementary to a sequence of the engineered guide ribonucleic acid structure and a second strand comprising the PAM. In some embodiments, the PAM is directly adjacent to the 3' end of the sequence complementary to the sequence of the engineered guide ribonucleic acid structure. In some embodiments, the class 2, type II Cas endonuclease is not a Cas9 endonuclease, a Cas 14 endonuclease, a Cas 12a endonuclease, a Cas 12b endonuclease, a Cas 12c endonuclease, a Cas 12d endonuclease, a Casl2e endonuclease, a Casl3a endonuclease, a Cas 13b endonuclease, a Cas 13c endonuclease, or a Cas 13d endonuclease. In some embodiments, the class 2, type II Cas endonuclease is derived from an uncultivated microorganism. In some embodiments, the double-stranded deoxyribonucleic acid polynucleotide is a eukaryotic, plant, fungal, mammalian, rodent, or human double-stranded deoxyribonucleic acid polynucleotide. In some embodiments: (a) the PAM comprises SEQ ID NO: 149 or SEQ ID NO: 154; (b) the PAM comprises SEQ ID NO: 150 or SEQ ID NO: 155; (c) the PAM comprises SEQ ID NO: 151 or SEQ ID NO: 156; (d) the PAM comprises SEQ ID NO: 152 or SEQ ID NO: 157; or (e)the PAM comprises SEQ ID NO: 153 or SEQ ID NO: 158. [0014] In some aspects, the present disclosure provides for a method of modifying a target nucleic acid locus, the method comprising delivering to the target nucleic acid locus any of the engineered nuclease systems described herein, wherein the endonuclease is configured to form a complex with the engineered guide ribonucleic acid structure, and wherein the complex is configured such that upon binding of the complex to the target nucleic acid locus, the complex modifies the target nucleic acid locus. In some embodiments, modifying the target nucleic acid locus comprises binding, nicking, cleaving, or marking the target nucleic acid locus. In some embodiments, the target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). In some embodiments, the target nucleic acid comprises genomic DNA, viral DNA, viral RNA, or bacterial DNA. In some embodiments, the target nucleic acid locus is in vitro. In some embodiments, the target nucleic acid locus is within a cell. In some embodiments, the cell is a prokaryotic cell, a bacterial cell, a eukaryotic cell, a fungal cell, a plant cell, an animal cell, a mammalian cell, a rodent cell, a primate cell, or a human cell. In some embodiments, delivering the engineered nuclease system to the target nucleic acid locus comprises delivering any of the nucleic acids described herein or any of the vectors described herein. In some embodiments, delivering the engineered nuclease system to the target nucleic acid locus comprises delivering a nucleic acid comprising an open reading frame encoding the endonuclease. In some embodiments, the nucleic acid comprises a promoter to which the open reading frame encoding the endonuclease is operably linked. In some embodiments, delivering the engineered nuclease system to the target nucleic acid locus comprises delivering a capped mRNA containing the open reading frame encoding the endonuclease. In some embodiments, delivering the engineered nuclease system to the target nucleic acid locus comprises delivering a translated polypeptide. In some embodiments, delivering the engineered nuclease system to the target nucleic acid locus comprises delivering a deoxyribonucleic acid (DNA) encoding the engineered guide ribonucleic acid structure operably linked to a ribonucleic acid (RNA) pol III promoter. In some embodiments, the endonuclease induces a single-stranded break or a double- stranded break at or proximal to the target locus.

[0015] Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. INCORPORATION BY REFERENCE

[0016] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and/or take precedence over any such contradictory material.

BRIEF DESCRIPTION OF THE DRAWINGS [0017] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also “Figure” and “FIG.” herein), of which:

[0018] FIGURE 1 depicts typical organization of CRISPR/Cas loci of different classes.

[0019] FIGURE 2 depicts the architecture of a natural Class II/Type II crRNA/tracrRNA pair, compared to a hybrid sgRNA wherein both are joined.

[0020] FIGURE 3 depicts schematics showing organization of CRISPR loci encoding enzymes from the MG6 family.

[0021] FIGURES 4A, 4B, and 4C depicts a structure-based alignment of an enzyme of the present disclosure (MG6-1) versus Cas9 from Staphylococcus aureus (SEQ ID NO: 196). Predicted residues essential for function are highlighted in black.

[0022] FIGURES 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H, 51, 5J and 5K depict a structure-based alignment of MG6 family enzymes MG6-1 through MG6-6 (SEQ ID NOs: 28-33). Predicted residues essential for function are highlighted in black.

[0023] FIGURES 6, 7, 8, and 9 depict agarose gels showing the results of PAM vector library cleavage in the presence of TXTL extracts containing various MG family nucleases and their corresponding tracrRNAs or sgRNAs.

[0024] FIGURE 10 depicts in cell cleavage of E. coli genomic DNA using MG6-3 along with its corresponding sgRNA. Shown are dilution series of cells transformed with MG6-3 along with target or non-target spacer (top); bottom panel shows the data quantitated, where the right bar represents non-target sgRNA and the left bar represents target sgRNA. [0025] FIGURE 11 depicts in vitro cleavage of DNA by MG7-1 in complex with its corresponding sgRNA containing a 22-nucleotide targeting sequence, showing that the MG7- 1/sgRNA combination is effective to cleave DNA.

[0026] FIGURE 12 depicts in cell cleavage of E. coli genomic DNA using MG7-1 along with its corresponding sgRNA. Shown are dilution series of cells transformed with MG7-1 along with target or non-target spacer (top); bottom panel shows the data quantitated, where the right bar represents non-target sgRNA and the left bar represents target sgRNA.

[0027] FIGURE 13 depicts in cell indel formation generated by transfection of HEK cells with MG7-1 as described in Example 13 alongside its corresponding sgRNAs containing various different targeting sequences targeting various locations in the human genome.

[0028] FIGURE 14 depicts in cell cleavage of E. coli genomic DNA using MG16-1 along with its corresponding sgRNA. Shown are dilution series of cells transformed with MG16-1 along with target or non-target spacer (top); bottom panel shows the data quantitated, where the right bar represents non-target sgRNA and the left bar represents target sgRNA.

[0029] FIGURES 15 and 16 depict predicted structures (predicted e.g., as in Example 7) of corresponding sgRNAs of MG enzymes described herein.

[0030] FIGURES 17, 18, and 19 depict seqLogo representations of PAM sequences derived via NGS as described herein (e.g. as described in Example 6).

[0031] FIGURE 20 depicts in cell indel formation generated by transfection of HEK cells with MG4-2 constructs described in Example 11 alongside their corresponding sgRNAs containing various different targeting sequences targeting various locations in the human genome.

[0032] FIGURE 21 depicts in cell indel formation generated by transfection of HEK cells with MG6-3 constructs described in Example 12 alongside their corresponding sgRNAs containing various different targeting sequences targeting various locations in the human genome.

[0033] FIGURE 22 depicts in cell indel formation generated by transfection of HEK cells with MG7-1 constructs described in Example 13 alongside their corresponding sgRNAs containing various different targeting sequences targeting various locations in the human genome.

[0034] FIGURE 23 depicts in cell indel formation generated by transfection of HEK cells with MG16-1 constructs described in Example 14 alongside their corresponding sgRNAs containing various different targeting sequences targeting various locations in the human genome.

[0035] FIGURE 24 depicts environmental distribution of nucleases described herein. Protein length is shown for representatives of selected protein families. Colors indicate the environment or environment type from which each protein was identified.

[0036] FIGURE 25 depicts predicted catalytic residues of nucleases described herein. Protein length is shown for representatives of selected protein families. Colors indicate the number of catalytic residues that were predicted for each protein. For the effector enzymes described herein, six catalytic residues were searched that correspond with the HNH and RuvC domains. [0037] FIGURE 26 depicts candidate activity of nucleases described herein versus protein length.

[0038] FIGURE 27 shows the number of predicted catalytic residues that may be present in nucleases described herein.

[0039] FIGURE 28 shows various characteristic information about selected nucleases described herein.

[0040] FIGURE 29 shows a consensus PAM sequence for an enzyme described herein.

BRIEF DESCRIPTION OF THE SEQUENCE LISTING [0041] The Sequence Listing filed herewith provides exemplary polynucleotide and polypeptide sequences for use in methods, compositions and systems according to the disclosure. Below are exemplary descriptions of sequences therein.

[0042] MG1

[0043] SEQ ID NO: 1 shows the full-length peptide sequences of an MG1 nucleases.

[0044] SEQ ID NO: 45 shows the peptide sequence of a RuvC III domains of MG1 nucleases above.

[0045] SEQ ID NO: 89 shows the peptide of HNH domains of MG1 nucleases above.

[0046] MG2

[0047] SEQ ID NOs: 2 shows the full-length peptide sequences of an MG2 nuclease.

[0048] SEQ ID NOs: 46 shows the peptide sequence of a RuvC III domain of the MG2 nuclease above.

[0049] SEQ ID NO: 90 shows the peptide of HNH domains of the MG2 nuclease above.

[0050] SEQ ID NO: 138 shows the nucleotide sequences of an MG2 tracrRNA derived from the same loci as MG2 nuclease above.

[0051] SEQ ID NO: 133 shows the nucleotide sequence of an sgRNAs engineered to function with the MG2 nuclease.

[0052] SEQ ID NO: 170 shows the nucleotide sequence of an E. coli codon-optimized coding sequence for an MG2 nuclease.

[0053] SEQ ID NO: 176 shows the nucleotide sequence of a human codon-optimized coding sequence for an MG2 nuclease. [0054] MG4

[0055] SEQ ID NOs: 4-27 show the full-length peptide sequences of MG4 nucleases.

[0056] SEQ ID NOs: 48-71 show the peptide sequences of RuvC III domains of MG4 nucleases above.

[0057] SEQ ID NOs: 92-115 show the peptide of HNH domains of MG4 nucleases above.

[0058] SEQ ID NOs: 139-143 show the nucleotide sequences of MG4 tracrRNAs derived from the same loci as MG4 nucleases above.

[0059] SEQ ID NO: 134 shows the nucleotide sequence of an sgRNA engineered to function with an MG4 nuclease.

[0060] SEQ ID NOs: 171-172 show nucleotide sequences of E. coli codon-optimized coding sequences for MG4 nucleases.

[0061] MG6

[0062] SEQ ID NOs: 28-39 and 229-236 show the full-length peptide sequences of MG6 nucleases.

[0063] SEQ ID NOs: 72-83 and 246-253 show the peptide sequences of RuvC III domains of MG6 nucleases above.

[0064] SEQ ID NOs: 116-127 and 263-270 show the peptide of HNH domains of MG6 nucleases above.

[0065] SEQ ID NOs: 144-146 show the nucleotide sequences of MG6 tracrRNAs derived from the same loci as MG6 nucleases above.

[0066] SEQ ID NO: 135 shows the nucleotide sequence of an sgRNA engineered to function with an MG6 nuclease.

[0067] SEQ ID NO: 173 shows a nucleotide sequence of an E. coli codon-optimized coding sequences for an MG6 nuclease.

[0068] SEQ ID NO: 177 shows a nucleotide sequence of a human codon-optimized coding sequence for an MG6 nuclease.

[0069] MG7

[0070] SEQ ID NOs: 40-42 and 237-245 show the full-length peptide sequences of MG7 nucleases.

[0071] SEQ ID NOs: 84-86 and 254-262 show the peptide sequences of RuvC III domains of MG7 nucleases above.

[0072] SEQ ID NOs: 128-130 and 271-279 show the peptide of HNH domains of MG7 nucleases above.

[0073] SEQ ID NO: 147 and 280 show the nucleotide sequences of an MG7 tracrRNA derived from the same loci as MG7 nucleases above.

[0074] SEQ ID NO: 136 shows the nucleotide sequence of sgRNAs engineered to function with an MG7 nuclease.

[0075] SEQ ID NO: 174 shows a nucleotide sequence of an E. coli codon-optimized coding sequences for an MG7 nuclease.

[0076] SEQ ID NO: 178 shows a nucleotide sequence of a human codon-optimized coding sequence for an MG7 nuclease.

[0077] MG16

[0078] SEQ ID NOs: 43-44 show the full-length peptide sequences of MG16 nucleases.

[0079] SEQ ID NOs: 87-88 show the peptide sequences of RuvC III domains of MG16 nucleases above.

[0080] SEQ ID NOs: 131-132 show the peptide of HNH domains of MG16 nucleases above. [0081] SEQ ID NO: 148 shows the nucleotide sequences of an MG16 tracrRNA derived from the same loci as a MG16 nuclease above.

[0082] SEQ ID NO: 137 shows the nucleotide sequence of sgRNAs engineered to function with an MG16 nuclease.

[0083] SEQ ID NO: 175 shows an E. coli codon-optimized coding sequences for an MG16 nuclease.

[0084] SEQ ID NO: 179 shows a human codon-optimized coding sequences for an MG16 nuclease.

[0085] MG48

[0086] SEQ ID NO: 292 shows the full-length peptide sequence of a MG48 nuclease.

[0087] MG49

[0088] SEQ ID NO: 293 shows the full-length peptide sequence of a MG49 nuclease.

DETAILED DESCRIPTION

[0089] While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed.

[0090] Whenever the term “at least,” “greater than,” or “greater than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “at least,” “greater than” or “greater than or equal to” applies to each of the numerical values in that series of numerical values. For example, greater than or equal to 1, 2, or 3 is equivalent to greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3.

[0091] Whenever the term “no more than,” “less than,” or “less than or equal to” precedes the first numerical value in a series of two or more numerical values, the term “no more than,” “less than,” or “less than or equal to” applies to each of the numerical values in that series of numerical values. For example, less than or equal to 3, 2, or 1 is equivalent to less than or equal to 3, less than or equal to 2, or less than or equal to 1.

[0092] The practice of some methods disclosed herein employ, unless otherwise indicated, techniques of immunology, biochemistry, chemistry, molecular biology, microbiology, cell biology, genomics and recombinant DNA. See for example Sambrook and Green, Molecular Cloning: A Laboratory Manual, 4th Edition (2012); the series Current Protocols in Molecular Biology (F. M. Ausubel, et al. eds.); the series Methods In Enzymology (Academic Press, Inc.), PCR 2: A Practical Approach (M.J. MacPherson, B.D. Hames and G.R. Taylor eds. (1995)), Harlow and Lane, eds. (1988) Antibodies, A Laboratory Manual, and Culture of Animal Cells:

A Manual of Basic Technique and Specialized Applications, 6th Edition (R.I. Freshney, ed. (2010)) (which is entirely incorporated by reference herein).

[0093] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising”.

[0094] The term “about” or “approximately” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, “about” can mean within one or more than one standard deviation, per the practice in the art. Alternatively, “about” can mean a range of up to 20%, up to 15%, up to 10%, up to 5%, or up to 1% of a given value.

[0095] As used herein, a “cell” generally refers to a biological cell. A cell may be the basic structural, functional and/or biological unit of a living organism. A cell may originate from any organism having one or more cells. Some non-limiting examples include: a prokaryotic cell, eukaryotic cell, a bacterial cell, an archaeal cell, a cell of a single-cell eukaryotic organism, a protozoa cell, a cell from a plant (e.g., cells from plant crops, fruits, vegetables, grains, soy bean, com, maize, wheat, seeds, tomatoes, rice, cassava, sugarcane, pumpkin, hay, potatoes, cotton, cannabis, tobacco, flowering plants, conifers, gymnosperms, ferns, clubmosses, hornworts, liverworts, mosses), an algal cell, (e.g.„ Botryococcus braunii, Chlamydomonas reinhardtii, Nannochloropsis gaditana, Chlorella pyrenoidosa, Sargassum patens C. Agardh, and the like), seaweeds (e.g., kelp), a fungal cell (e.g.„ a yeast cell, a cell from a mushroom), an animal cell, a cell from an invertebrate animal (e.g., fruit fly, cnidarian, echinoderm, nematode, etc.), a cell from a vertebrate animal (e.g., fish, amphibian, reptile, bird, mammal), a cell from a mammal (e.g., a pig, a cow, a goat, a sheep, a rodent, a rat, a mouse, a non-human primate, a human, etc.), and etcetera. Sometimes a cell is not originating from a natural organism (e.g., a cell can be a synthetically made, sometimes termed an artificial cell).

[0096] The term “nucleotide,” as used herein, generally refers to a base-sugar-phosphate combination. A nucleotide may comprise a synthetic nucleotide. A nucleotide may comprise a synthetic nucleotide analog. Nucleotides may be monomeric units of a nucleic acid sequence (e.g., deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)). The term nucleotide may include ribonucleoside triphosphates adenosine triphosphate (ATP), uridine triphosphate (UTP), cytosine triphosphate (CTP), guanosine triphosphate (GTP) and deoxyribonucleoside triphosphates such as dATP, dCTP, dITP, dUTP, dGTP, dTTP, or derivatives thereof. Such derivatives may include, for example, [aSJdATP, 7-deaza-dGTP and 7-deaza-dATP, and nucleotide derivatives that confer nuclease resistance on the nucleic acid molecule containing them. The term nucleotide as used herein may refer to dideoxyribonucleoside triphosphates (ddNTPs) and their derivatives. Illustrative examples of dideoxyribonucleoside triphosphates may include, but are not limited to, ddATP, ddCTP, ddGTP, ddITP, and ddTTP. A nucleotide may be unlabeled or detectably labeled, such as using moieties comprising optically detectable moieties (e.g., fluorophores). Labeling may also be carried out with quantum dots. Detectable labels may include, for example, radioactive isotopes, fluorescent labels, chemiluminescent labels, bioluminescent labels and enzyme labels. Fluorescent labels of nucleotides may include but are not limited fluorescein, 5-carboxyfluorescein (FAM), 2'7'-dimethoxy-4'5-dichloro-6- carboxyfluorescein (JOE), rhodamine, 6-carboxyrhodamine (R6G), N,N,N',N'-tetramethyl-6- carboxyrhodamine (TAMRA), 6-carboxy-X-rhodamine (ROX), 4-(4'dimethylaminophenylazo) benzoic acid (DABCYL), Cascade Blue, Oregon Green, Texas Red, Cyanine and 5-(2'- aminoethyl)aminonaphthalene-l -sulfonic acid (EDANS). Specific examples of fluorescently labeled nucleotides can include [R6G]dUTP, [TAMRA]dUTP, [R110]dCTP, [R6G]dCTP, [TAMRA]dCTP, [JOE]ddATP, [R6G] ddATP, [FAM] ddCTP, [R110]ddCTP, [TAMRA]ddGTP, [ROX]ddTTP, [dR6G] ddATP, [dR110]ddCTP, [dTAMRA] ddGTP, and [dROX]ddTTP available from Perkin Elmer, Foster City, Calif; FluoroLink DeoxyNucleotides, FluoroLink Cy3-dCTP, FluoroLink Cy5-dCTP, FluoroLink Fluor X-dCTP, FluoroLink Cy3-dUTP, and FluoroLink Cy5-dUTP available from Amersham, Arlington Heights, Ill.; Fluorescein- 15 -d ATP, Fluorescein- 12-dUTP, Tetramethyl-rodamine-6-dUTP, IR770-9-dATP, Fluorescein- 12-ddUTP, Fluorescein- 12-UTP, and Fluorescein- 15 -2 '-d ATP available from Boehringer Mannheim, Indianapolis, Ind.; and Chromosome Labeled Nucleotides, BODIPY-FL-14-UTP, BODIPY-FL- 4-UTP, BODIP Y -TMR- 14-UTP, BODIPY-TMR-14-dUTP, BODIP Y -TR- 14-UTP, BODIP Y- TR-14-dUTP, Cascade Blue-7-UTP, Cascade Blue-7-dUTP, fluorescein- 12-UTP, fluorescein- 12-dUTP, Oregon Green 488-5-dUTP, Rhodamine Green-5-UTP, Rhodamine Green-5-dUTP, tetramethylrhodamine-6-UTP, tetramethylrhodamine-6-dUTP, Texas Red-5-UTP, Texas Red-5- dUTP, and Texas Red-12-dUTP available from Molecular Probes, Eugene, Oreg. Nucleotides can also be labeled or marked by chemical modification. A chemically-modified single nucleotide can be biotin-dNTP. Some non-limiting examples of biotinylated dNTPs can include, biotin-dATP (e.g., bio-N6-ddATP, biotin- 14-dATP), biotin-dCTP (e.g., biotin- 11-dCTP, biotin- 14-dCTP), and biotin-dUTP (e.g., biotin- 11-dUTP, biotin- 16-dUTP, biotin-20-dUTP).

[0097] The terms “polynucleotide,” “oligonucleotide,” and “nucleic acid” are used interchangeably to generally refer to a polymeric form of nucleotides of any length, either deoxyribonucleotides or ribonucleotides, or analogs thereof, either in single-, double-, or multi- stranded form. A polynucleotide may be exogenous or endogenous to a cell. A polynucleotide may exist in a cell-free environment. A polynucleotide may be a gene or fragment thereof. A polynucleotide may be DNA. A polynucleotide may be RNA. A polynucleotide may have any three-dimensional structure and may perform any function. A polynucleotide may comprise one or more analogs (e.g., altered backbone, sugar, or nucleobase). If present, modifications to the nucleotide structure may be imparted before or after assembly of the polymer. Some non limiting examples of analogs include: 5-bromouracil, peptide nucleic acid, xeno nucleic acid, morpholinos, locked nucleic acids, glycol nucleic acids, threose nucleic acids, dideoxynucleotides, cordycepin, 7-deaza-GTP, fluorophores (e.g., rhodamine or fluorescein linked to the sugar), thiol containing nucleotides, biotin linked nucleotides, fluorescent base analogs, CpG islands, methyl-7-guanosine, methylated nucleotides, inosine, thiouridine, pseudourdine, dihydrouridine, queuosine, and wyosine. Non-limiting examples of polynucleotides include coding or non-coding regions of a gene or gene fragment, loci (locus) defined from linkage analysis, exons, introns, messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), short interfering RNA (siRNA), short-hairpin RNA (shRNA), micro- RNA (miRNA), ribozymes, cDNA, recombinant polynucleotides, branched polynucleotides, plasmids, vectors, isolated DNA of any sequence, isolated RNA of any sequence, cell-free polynucleotides including cell-free DNA (cfDNA) and cell-free RNA (cfRNA), nucleic acid probes, and primers. The sequence of nucleotides may be interrupted by non-nucleotide components.

[0098] The terms “transfection” or “transfected” generally refer to introduction of a nucleic acid into a cell by non-viral or viral-based methods. The nucleic acid molecules may be gene sequences encoding complete proteins or functional portions thereof. See, e.g., Sambrook et al., 1989, Molecular Cloning: A Laboratory Manual, 18.1-18.88.

[0099] The terms “peptide,” “polypeptide,” and “protein” are used interchangeably herein to generally refer to a polymer of at least two amino acid residues joined by peptide bond(s). This term does not connote a specific length of polymer, nor is it intended to imply or distinguish whether the peptide is produced using recombinant techniques, chemical or enzymatic synthesis, or is naturally occurring. The terms apply to naturally occurring amino acid polymers as well as amino acid polymers comprising at least one modified amino acid. In some cases, the polymer may be interrupted by non-amino acids. The terms include amino acid chains of any length, including full length proteins, and proteins with or without secondary and/or tertiary structure (e.g., domains). The terms also encompass an amino acid polymer that has been modified, for example, by disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, oxidation, and any other manipulation such as conjugation with a labeling component. The terms “amino acid” and “amino acids,” as used herein, generally refer to natural and non-natural amino acids, including, but not limited to, modified amino acids and amino acid analogues. Modified amino acids may include natural amino acids and non-natural amino acids, which have been chemically modified to include a group or a chemical moiety not naturally present on the amino acid. Amino acid analogues may refer to amino acid derivatives. The term “amino acid” includes both D-amino acids and L-amino acids.

[00100] As used herein, the “non-native” can generally refer to a nucleic acid or polypeptide sequence that is not found in a native nucleic acid or protein. Non-native may refer to affinity tags. Non-native may refer to fusions. Non-native may refer to a naturally occurring nucleic acid or polypeptide sequence that comprises mutations, insertions and/or deletions. A non-native sequence may exhibit and/or encode for an activity (e.g., enzymatic activity, methyltransferase activity, acetyltransferase activity, kinase activity, ubiquitinating activity, etc.) that may also be exhibited by the nucleic acid and/or polypeptide sequence to which the non native sequence is fused. A non-native nucleic acid or polypeptide sequence may be linked to a naturally-occurring nucleic acid or polypeptide sequence (or a variant thereof) by genetic engineering to generate a chimeric nucleic acid and/or polypeptide sequence encoding a chimeric nucleic acid and/or polypeptide. [00101] The term “promoter”, as used herein, generally refers to the regulatory DNA region which controls transcription or expression of a gene and which may be located adjacent to or overlapping a nucleotide or region of nucleotides at which RNA transcription is initiated. A promoter may contain specific DNA sequences which bind protein factors, often referred to as transcription factors, which facilitate binding of RNA polymerase to the DNA leading to gene transcription. A ‘basal promoter’, also referred to as a ‘core promoter’, may generally refer to a promoter that contains all the basic necessary elements to promote transcriptional expression of an operably linked polynucleotide. Eukaryotic basal promoters typically, though not necessarily, contain a TATA-box and/or a CAAT box.

[00102] The term “expression”, as used herein, generally refers to the process by which a nucleic acid sequence or a polynucleotide is transcribed from a DNA template (such as into mRNA or other RNA transcript) and/or the process by which a transcribed mRNA is subsequently translated into peptides, polypeptides, or proteins. Transcripts and encoded polypeptides may be collectively referred to as “gene product.” If the polynucleotide is derived from genomic DNA, expression may include splicing of the mRNA in a eukaryotic cell.

[00103] As used herein, “operably linked”, “operable linkage”, “operatively linked”, or grammatical equivalents thereof generally refer to juxtaposition of genetic elements, e.g., a promoter, an enhancer, a polyadenylation sequence, etc., wherein the elements are in a relationship permitting them to operate in the expected manner. For instance, a regulatory element, which may comprise promoter and/or enhancer sequences, is operatively linked to a coding region if the regulatory element helps initiate transcription of the coding sequence. There may be intervening residues between the regulatory element and coding region so long as this functional relationship is maintained.

[00104] A “vector” as used herein, generally refers to a macromolecule or association of macromolecules that comprises or associates with a polynucleotide and which may be used to mediate delivery of the polynucleotide to a cell. Examples of vectors include plasmids, viral vectors, liposomes, and other gene delivery vehicles. The vector generally comprises genetic elements, e.g., regulatory elements, operatively linked to a gene to facilitate expression of the gene in a target.

[00105] As used herein, “an expression cassette” and “a nucleic acid cassette” are used interchangeably generally to refer to a combination of nucleic acid sequences or elements that are expressed together or are operably linked for expression. In some cases, an expression cassette refers to the combination of regulatory elements and a gene or genes to which they are operably linked for expression. [00106] A “functional fragment” of a DNA or protein sequence generally refers to a fragment that retains a biological activity (either functional or structural) that is substantially similar to a biological activity of the full-length DNA or protein sequence. A biological activity of a DNA sequence may be its ability to influence expression in a manner known to be attributed to the full-length sequence.

[00107] As used herein, “engineered” with reference to a protein, generally refers to a non-naturally occurring protein or nucleic acid, including, but not limited to, a protein that is derived from a naturally occurring protein, or where a naturally occurring protein has been modified or reprogrammed to have a certain property. An engineered system comprises at least one engineered component.

[00108] As used herein, “synthetic” and “artificial” are used interchangeably to refer to a protein or a domain thereof that has low sequence identity (e.g., less than 50% sequence identity, less than 25% sequence identity, less than 10% sequence identity, less than 5% sequence identity, less than 1% sequence identity) to a naturally occurring human protein. For example, VPR and VP64 domains are synthetic transactivation domains.

[00109] The term “tracrRNA” or “tracr sequence”, as used herein, can generally refer to a nucleic acid with at least about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or 100% sequence identity and/or sequence similarity to a wild type exemplary tracrRNA sequence (e.g., a tracrRNA from S. pyogenes S. aureus, etc). tracrRNA can refer to a nucleic acid with at most about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% sequence identity and/or sequence similarity to a wild type exemplary tracrRNA sequence (e.g., a tracrRNA from S. pyogenes S. aureus, etc). tracrRNA may refer to a modified form of a tracrRNA that can comprise a nucleotide change such as a deletion, insertion, or substitution, variant, mutation, or chimera. A tracrRNA may refer to a nucleic acid that can be at least about 60% identical to a wild type exemplary tracrRNA (e.g., a tracrRNA from S. pyogenes S. aureus, etc) sequence over a stretch of at least 6 contiguous nucleotides. For example, a tracrRNA sequence can be at least about 60% identical, at least about 65% identical, at least about 70% identical, at least about 75% identical, at least about 80% identical, at least about 85% identical, at least about 90% identical, at least about 95% identical, at least about 98% identical, at least about 99% identical, or 100 % identical to a wild type exemplary tracrRNA (e.g., a tracrRNA from S. pyogenes S. aureus, etc) sequence over a stretch of at least 6 contiguous nucleotides.

[00110] As used herein, a “guide nucleic acid” can generally refer to a nucleic acid that may hybridize to another nucleic acid. A guide nucleic acid may be RNA. A guide nucleic acid may be DNA. The guide nucleic acid may be programmed to bind to a sequence of nucleic acid site-specifically. The nucleic acid to be targeted, or the target nucleic acid, may comprise nucleotides. The guide nucleic acid may comprise nucleotides. A portion of the target nucleic acid may be complementary to a portion of the guide nucleic acid. The strand of a double- stranded target polynucleotide that is complementary to and hybridizes with the guide nucleic acid may be called the complementary strand. The strand of the double-stranded target polynucleotide that is complementary to the complementary strand, and therefore may not be complementary to the guide nucleic acid may be called noncomplementary strand. A guide nucleic acid may comprise a polynucleotide chain and can be called a “single guide nucleic acid.” A guide nucleic acid may comprise two polynucleotide chains and may be called a “double guide nucleic acid.” If not otherwise specified, the term “guide nucleic acid” may be inclusive, referring to both single guide nucleic acids and double guide nucleic acids. A guide nucleic acid may comprise a segment that can be referred to as a “nucleic acid-targeting segment” or a “nucleic acid-targeting sequence.” A nucleic acid-targeting segment may comprise a sub-segment that may be referred to as a “protein binding segment” or “protein binding sequence” or “Cas protein binding segment”.

[00111] The term “sequence identity” or “percent identity” in the context of two or more nucleic acids or polypeptide sequences, generally refers to two (e.g., in a pairwise alignment) or more (e.g., in a multiple sequence alignment) sequences that are the same or have a specified percentage of amino acid residues or nucleotides that are the same, when compared and aligned for maximum correspondence over a local or global comparison window, as measured using a sequence comparison algorithm. Suitable sequence comparison algorithms for polypeptide sequences include, e.g., BLASTP using parameters of a wordlength (W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment for polypeptide sequences longer than 30 residues; BLASTP using parameters of a wordlength (W) of 2, an expectation (E) of 1000000, and the PAM30 scoring matrix setting gap costs at 9 to open gaps and 1 to extend gaps for sequences of less than 30 residues (these are the default parameters for BLASTP in the BLAST suite available at https://blast.ncbi.nlm.nih.gov) ; CLUSTALW with parameters of the Smith-Waterman homology search algorithm with parameters of a match of 2, a mismatch of -1, and a gap of -1; MUSCLE with default parameters; MAFFT with parameters retree of 2 and maxiterations of 1000; Novafold with default parameters. As used herein, the term “RuvC III domain” generally refers to a third discontinuous segment of a RuvC endonuclease domain (the RuvC nuclease domain being comprised of three discontinuous segments, RuvC I, RuvC II, and RuvC III). [00112] Included in the current disclosure are variants of any of the enzymes described herein with one or more conservative amino acid substitutions. Such conservative substitutions can be made in the amino acid sequence of a polypeptide without disrupting the three-dimensional structure or function of the polypeptide. Conservative substitutions can be accomplished by substituting amino acids with similar hydrophobicity, polarity, and R chain length for one another. Additionally or alternatively, by comparing aligned sequences of homologous proteins from different species, conservative substitutions can be identified by locating amino acid residues that have been mutated between species (e.g. non-conserved residues) without altering the basic functions of the encoded proteins. Such conservatively substituted variants may include variants with at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% identity to any one of the endonuclease protein sequences described herein (e.g. MG1, MG2, MG4, MG6, MG7, or MG16 family endonucleases described herein). In some embodiments, such conservatively substituted variants are functional variants. Such functional variants can encompass sequences with substitutions such that the activity of critical active site residues of the endonuclease are not disrupted. In some embodiments, a functional variant of any of the proteins described herein lacks substitution of at least one of the residues predicted as essential in FIGURES 4A, 4B, 4C, 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H, 51, 5J or 5K.

In some embodiments, a functional variant of any of the proteins described herein lacks substitution of all of the residues predicted as essential in FIGURES 4A, 4B, 4C, 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H, 51, 5J or 5K.

[00113] Conservative substitution tables providing functionally similar amino acids are available from a variety of references (see, for e.g., Creighton, Proteins: Structures and Molecular Properties (W H Freeman & Co.; 2nd edition (December 1993)). The following eight groups each contain amino acids that are conservative substitutions for one another:

1) Alanine (A), Glycine (G);

2) Aspartic acid (D), Glutamic acid (E);

3) Asparagine (N), Glutamine (Q);

4) Arginine (R), Lysine (K); 5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V);

6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W);

7) Serine (S), Threonine (T); and

8) Cysteine (C), Methionine (M)

[00114] Overview

[00115] The discovery of new Cas enzymes with unique functionality and structure may offer the potential to further disrupt deoxyribonucleic acid (DNA) editing technologies, improving speed, specificity, functionality, and ease of use. Relative to the predicted prevalence of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) systems in microbes and the sheer diversity of microbial species, relatively few functionally characterized CRISPR/Cas enzymes exist in the literature. This is partly because a huge number of microbial species may not be readily cultivated in laboratory conditions. Metagenomic sequencing from natural environmental niches that represent large numbers of microbial species may offer the potential to drastically increase the number of new CRISPR/Cas systems known and speed the discovery of new oligonucleotide editing functionalities. A recent example of the fruitfulness of such an approach is demonstrated by the 2016 discovery of CasX/CasY CRISPR systems from metagenomic analysis of natural microbial communities.

[00116] CRISPR/Cas systems are RNA-directed nuclease complexes that have been described to function as an adaptive immune system in microbes. In their natural context, CRISPR/Cas systems occur in CRISPR (clustered regularly interspaced short palindromic repeats) operons or loci, which generally comprise two parts: (i) an array of short repetitive sequences (30-40bp) separated by equally short spacer sequences, which encode the RNA-based targeting element; and (ii) ORFs encoding the Cas encoding the nuclease polypeptide directed by the RNA-based targeting element alongside accessory proteins/enzymes. Efficient nuclease targeting of a particular target nucleic acid sequence generally requires both (i) complementary hybridization between the first 6-8 nucleic acids of the target (the target seed) and the crRNA guide; and (ii) the presence of a protospacer-adjacent motif (PAM) sequence within a defined vicinity of the target seed (the PAM usually being a sequence not commonly represented within the host genome). Depending on the exact function and organization of the system, CRISPR- Cas systems are commonly organized into 2 classes, 5 types and 16 subtypes based on shared functional characteristics and evolutionary similarity. [00117] Class I CRISPR-Cas systems have large, multisubunit effector complexes, and comprise Types I, III, and IV.

[00118] Type I CRISPR-Cas systems are considered of moderate complexity in terms of components. In Type I CRISPR-Cas systems, the array of RNA-targeting elements is transcribed as a long precursor crRNA (pre-crRNA) that is processed at repeat elements to liberate short, mature crRNAs that direct the nuclease complex to nucleic acid targets when they are followed by a suitable short consensus sequence called a protospacer-adjacent motif (PAM). This processing occurs via an endoribonuclease subunit (Cas6) of a large endonuclease complex called Cascade, which also comprises a nuclease (Cas3) that protein component of the crRNA- directed nuclease complex. Cas I nucleases function primarily as DNA nucleases.

[00119] Type III CRISPR systems may be characterized by the presence of a central nuclease, known as Cas 10, alongside a repeat-associated mysterious protein (RAMP) that comprises Csm or Cmr protein subunits. Like in Type I systems, the mature crRNA is processed from a pre-crRNA using a Cas6-like enzyme. Unlike type I and II systems, type III systems appear to target and cleave DNA-RNA duplexes (such as DNA strands being used as templates for an RNA polymerase).

[00120] Type IV CRISPR-Cas systems possess an effector complex that consists of a highly reduced large subunit nuclease (csfl), two genes for RAMP proteins of the Cas5 (csf3) and Cas7 (csf2) groups, and, in some cases, a gene for a predicted small subunit; such systems are commonly found on endogenous plasmids.

[00121] Class II CRISPR-Cas systems generally have single-polypeptide multidomain nuclease effectors, and comprise Types II, V and VI.

[00122] Type II CRISPR-Cas systems are considered the simplest in terms of components. In Type II CRISPR-Cas systems, the processing of the CRISPR array into mature crRNAs does not require the presence of a special endonuclease subunit, but rather a small trans-encoded crRNA (tracrRNA) with a region complementary to the array repeat sequence; the tracrRNA interacts with both its corresponding effector nuclease (Cas9) and the repeat sequence to form a precursor dsRNA structure, which is cleaved by endogenous RNAse III to generate a mature Cas9 enzyme loaded with both tracrRNA and crRNA. Cas II nucleases are known as DNA nucleases. The Cas9 effector has a characteristic structure, consisting of a RuvC-like endonuclease domain that adopts the RNase H fold with an unrelated HNH nuclease domain inserted within the folds of the RuvC-like nuclease domain. The RuvC-like domain is responsible for the cleavage of the target (e.g., crRNA complementary) DNA strand, while the HNH domain is responsible for cleavage of the displaced DNA strand. [00123] Type V CRISPR-Cas systems are characterized by a nuclease effector (Casl2) structure similar to that of Type II/Cas9, comprising a RuvC-like domain. Similar to Type II, most (but not all) Type V CRISPR systems use a tracrRNA to process pre-crRNAs into mature crRNAs; however, unlike Type II systems which requires RNAse III to cleave the pre-crRNA into multiple crRNAs, type V systems are capable of using the effector nuclease itself (Casl2) to cleave pre-crRNAs. Like Type-II CRISPR-Cas systems, Type V CRISPR-Cas systems are again known as DNA nucleases. Unlike Type II CRISPR-Cas systems, some Type V enzymes (e.g., Casl2a) appear to have a robust single-stranded nonspecific deoxyribonuclease activity that is activated by the first crRNA directed cleavage of a double-stranded target sequence.

[00124] Type VI CRIPSR-Cas systems are unique in that they appear to be the only class so far known as RNA-guided RNA endonucleases. Instead of RuvC-like domains, the single polypeptide effector of Type VI systems (Casl3) comprises two HEPN ribonuclease domains. Differing from both Type II and V systems, Type VI systems also appear to not need a tracrRNA for processing of pre-crRNA into crRNA. Similar to type V systems, however, some Type VI systems (e.g., C2C2) appear to possess robust single-stranded nonspecific nuclease (ribonuclease) activity activated by the first crRNA directed cleavage of a target RNA.

[00125] Because of their simpler architecture, Class II CRISPR-Cas have been most widely adopted for engineering and development as designer nuclease/genome editing applications.

[00126] One of the early adaptations of such a system for in vitro use can be found in

Jinek et al. (Science. 2012 Aug 17;337(6096):816-21, which is entirely incorporated herein by reference). The Jinek study first described a system that involved (i) recombinantly-expressed, purified full-length Cas9 (e.g., Class II, Type II Cas enzyme) isolated from S. pyogenes SF370, (ii) purified mature ~42 nt crRNA bearing a ~20 nt 5’ sequence complementary to the target DNA sequence desired to be cleaved followed by a 3’ tracr-binding sequence (the whole crRNA being in vitro transcribed from a synthetic DNA template carrying a T7 promoter sequence); (iii) purified tracrRNA in vitro transcribed from a synthetic DNA template carrying a T7 promoter sequence, and (iv) Mg2+. Jinek later described an improved, engineered system wherein the crRNA of (ii) is joined to the 5’ end of (iii) by a linker (e.g., GAAA) to form a single fused synthetic guide RNA (sgRNA) capable of directing Cas9 to a target by itself (compare top and bottom panel of FIGURE 2).

[00127] Mali et al. (Science. 2013 Feb 15; 339(6121): 823-826.), which is entirely incorporated herein by reference, later adapted this system for use in mammalian cells by providing DNA vectors encoding (i) an ORF encoding codon-optimized Cas9 (e.g., Class II, Type II Cas enzyme) under a suitable mammalian promoter with a C-terminal nuclear localization sequence (e.g., SV40 NLS) and a suitable polyadenylation signal (e.g., TK pA signal); and (ii) an ORF encoding an sgRNA (having a 5’ sequence beginning with G followed by 20 nt of a complementary targeting nucleic acid sequence joined to a 3’ tracr-binding sequence, a linker, and the tracrRNA sequence) under a suitable Polymerase III promoter (e.g., the U6 promoter) .

[00128] MG Enzymes

[00129] In one aspect, the present disclosure provides for an engineered nuclease system discovered through metagenomic sequencing. In some cases, the metagenomic sequencing is conducted on samples. In some cases, the samples may be collected by a variety of environments. Such environments may be a human microbiome, an animal microbiome, environments with high temperatures, environments with low temperatures. Such environments may include sediment. An example of the types of such environments of the engineered nuclease systems described herein may be found in Figure 24.

MG1 enzymes

[00130] In one aspect, the present disclosure provides for an engineered nuclease system comprising (a) an endonuclease. In some cases, the endonuclease is a Cas endonuclease. In some cases, the endonuclease is a Type II, Class II Cas endonuclease. The endonuclease may comprise a RuvC III domain, wherein said RuvC III domain has at least about 70% sequence identity to SEQ ID NO: 45 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain has at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% identity to any one of SEQ ID NOs: 45 or a functional variant thereof. The endonuclease may comprise a RuvC III domain substantially identical to SEQ ID NOs: 45 or a functional variant thereof.

[00131] The endonuclease may comprise an HNH domain having at least about 70% identity to SEQ ID NO: 89 or a functional variant thereof. In some cases, the endonuclease may comprise an HNH domain having at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical SEQ ID NOs: 89 or a functional variant thereof. The endonuclease may comprise an HNH domain substantially identical to SEQ ID NOs: 89 or a functional variant thereof.

[00132] In some cases, the endonuclease may comprise a variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 1 or a functional variant thereof . In some cases, the endonuclease may be substantially identical to SEQ ID NOs: 1 or a functional variant thereof.

[00133] In some cases, the endonuclease may comprise a variant having one or more nuclear localization sequences (NLSs). The NLS may be proximal to the N- or C-terminus of said endonuclease. The NLS may be appended N-terminal or C-terminal to SEQ ID NOs: 1 or a functional variant thereof, or to a variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NOs: 1. The NLS may be an SV40 large T antigen NLS. The NLS may be a c-myc NLS. The NLS can comprise a sequence with at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99% identity to any one of SEQ ID NOs: 180-195. The NLS can comprise a sequence substantially identical to any one of SEQ ID NOs: 180-195. The NLS can comprise any of the sequences in Table 1 below, or a combination thereof:

[00134] Table 1: Example NLS Sequences that can be used with Cas Effectors According to the Disclosure

[00135] In some cases, the endonuclease may be recombinant (e.g., cloned, expressed, and purified by a suitable method such as expression in E. cob followed by epitope-tag purification). [00136] In some cases, sequence identity may be determined by the BLASTP,

CLUSTALW, MUSCLE, MAFFT, Novafold, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. The sequence identity may be determined by the BLASTP algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and using a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

[00137] In some cases, the system above may comprise (b) at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease bearing a 5’ targeting region complementary to a desired cleavage sequence. In some cases, the 5’ targeting region may comprises a PAM sequence compatible with the endonuclease. In some cases, the 5’ most nucleotide of the targeting region may be G. In some cases, the 5’ targeting region may be 15-23 nucleotides in length. The guide sequence and the tracr sequence may be supplied as separate ribonucleic acids (RNAs) or a single ribonucleic acid (RNA). The guide RNA may comprise a crRNA tracrRNA binding sequence 3 ’ to the targeting region. The guide RNA may comprise a tracrRNA sequence preceded by a 4-nucleotide linker 3’ to the crRNA tracrRNA binding region. The sgRNA may comprise, from 5' to 3': a non-natural guide nucleic acid sequence capable of hybridizing to a target sequence in a cell; and a tracr sequence. In some cases, the non-natural guide nucleic acid sequence and the tracr sequence are covalently linked. [00138] In some cases, the tracr sequence may have a particular sequence. The tracr sequence may have at least about 80% to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of a natural tracrRNA sequence.

[00139] In some cases, the system above may comprise two different sgRNAs or guide RNAs targeting a first region and a second region for cleavage in a target DNA locus, wherein the second region is 3’ to the first region. In some cases, the system above may comprise a single- or double-stranded DNA repair template comprising from 5’ to 3’ : a first homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 5’ to the first region, a synthetic DNA sequence of at least about 10 nucleotides, and a second homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 3’ to the second region.

[00140] In another aspect, the present disclosure provides a method for modifying a target nucleic acid locus. The method may comprise delivering to the target nucleic acid locus any of the non-natural systems disclosed herein, including an enzyme and at least one synthetic guide RNA (sgRNA) disclosed herein. The enzyme may form a complex with the at least one sgRNA, and upon binding of the complex to the target nucleic acid locus, may modify the target nucleic acid locus. Delivering the enzyme to said locus may comprise transfecting a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise electroporating a cell with the system or nucleic acids encoding the system.

Delivering the nuclease to said locus may comprise incubating the system in a buffer with a nucleic acid comprising the locus of interest. In some cases, the target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). The target nucleic acid locus may comprise genomic DNA, viral DNA, viral RNA, or bacterial DNA. The target nucleic acid locus may be within a cell. The target nucleic acid locus may be in vitro. The target nucleic acid locus may be within a eukaryotic cell or a prokaryotic cell. The cell may be an animal cell, a human cell, bacterial cell, archaeal cell, or a plant cell. The enzyme may induce a single or double-stranded break at or proximal to the target locus of interest.

[00141] In cases where the target nucleic acid locus may be within a cell, the enzyme may be supplied as a nucleic acid containing an open reading frame encoding the enzyme having a RuvC III domain having at least about 75% (e.g., at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%) identity to SEQ ID NO: 1 or a functional variant thereof. In some cases, the nucleic acid comprises a promoter to which the open reading frame encoding the endonuclease is operably linked. The promoter may be a CMV, EFla, SV40, PGK1, Ubc, human beta actin, CAG, TRE, or CaMKIIa promoter. The endonuclease may be supplied as a capped mRNA containing said open reading frame encoding said endonuclease. The endonuclease may be supplied as a translated polypeptide. The at least one engineered sgRNA may be supplied as deoxyribonucleic acid (DNA) containing a gene sequence encoding said at least one engineered sgRNA operably linked to a ribonucleic acid (RNA) pol III promoter. In some cases, the organism may be eukaryotic. In some cases, the organism may be fungal. In some cases, the organism may be human.

[00142] In some cases, the present disclosure may provide for an expression cassette comprising the system disclosed herein, or the nucleic acid described herein. In some cases, the expression cassette or nucleic acid may be supplied as a vector. In some cases, the expression cassette, nucleic acid, or vector may be supplied in a cell.

[00143] MG2 enzymes

[00144] In one aspect, the present disclosure provides for an engineered nuclease system comprising (a) an endonuclease. In some cases, the endonuclease is a Cas endonuclease. In some cases, the endonuclease is a Type II, Class II Cas endonuclease. The endonuclease may comprise a RuvC III domain, wherein said RuvC III domain has at least about 70% sequence identity to SEQ ID NO: 46 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain has at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% identity to SEQ ID NO:

46 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain is substantially identical to SEQ ID NO: 46.

[00145] The endonuclease may comprise an HNH domain having at least about 70% identity to SEQ ID NO: 90 or a functional variant thereof. In some cases, the endonuclease may comprise an HNH domain having at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical to SEQ ID NO: 90 or a functional variant thereof. The endonuclease may comprise an HNH domain substantially identical to SEQ ID NO: 90 or a functional variant thereof.

[00146] In some cases, the endonuclease may comprise a variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 2 or a functional variant thereof . In some cases, the endonuclease may be substantially identical to SEQ ID NO: 2 or a functional variant thereof.

[00147] In some cases, the endonuclease may comprise a variant having one or more nuclear localization sequences (NLSs). The NLS may be proximal to the N- or C-terminus of said endonuclease. The NLS may be appended N-terminal or C-terminal to SEQ ID NO: 2, or to a functional variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 2. The NLS may be an SV40 large T antigen NLS. The NLS may be a c-myc NLS. The NLS can comprise a sequence with at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99% identity to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise a sequence substantially identical to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise any of the sequences in Table 1 or a combination thereof:

[00148] In some cases, sequence identity may be determined by the BLASTP, CLUSTALW, MUSCLE, MAFFT, Novafold, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. The sequence identity may be determined by the BLASTP algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and using a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

[00149] In some cases, the system above may comprise (b) at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease bearing a 5’ targeting region complementary to a desired cleavage sequence. In some cases, the 5’ targeting region may comprises a PAM sequence compatible with the endonuclease. In some cases, the 5’ most nucleotide of the targeting region may be G. In some cases, the 5’ targeting region may be 15-23 nucleotides in length. The guide sequence and the tracr sequence may be supplied as separate ribonucleic acids (RNAs) or a single ribonucleic acid (RNA). The guide RNA may comprise a crRNA tracrRNA binding sequence 3 ’ to the targeting region. The guide RNA may comprise a tracrRNA sequence preceded by a 4-nucleotide linker 3’ to the crRNA tracrRNA binding region. The sgRNA may comprise, from 5' to 3': a non-natural guide nucleic acid sequence capable of hybridizing to a target sequence in a cell; and a tracr sequence. In some cases, the non-natural guide nucleic acid sequence and the tracr sequence are covalently linked. [00150] In some cases, the tracr sequence may have a particular sequence. The tracr sequence may have at least about 80% to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of a natural tracrRNA sequence. The tracr sequence may have at least about 80% sequence identity to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of SEQ ID NO: 138 or a functional variant thereof. In some cases, the tracrRNA may be substantially identical to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of SEQ ID NO: 138 or a functional variant thereof. The tracrRNA may comprise SEQ ID NOs: 138.

[00151] In some cases, the at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease may comprise a sequence having at least about 80% identity to SEQ ID NO: 133 or a functional variant thereof. The sgRNA may comprise a sequence having at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 133 or a functional variant thereof. The sgRNA may comprise a sequence substantially identical to SEQ ID NO: 133 or a functional variant thereof.

[00152] In some cases, the system above may comprise two different sgRNAs targeting a first region and a second region for cleavage in a target DNA locus, wherein the second region is 3’ to the first region. In some cases, the system above may comprise a single- or double- stranded DNA repair template comprising from 5’ to 3’ : a first homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 5’ to the first region, a synthetic DNA sequence of at least about 10 nucleotides, and a second homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 3’ to the second region.

[00153] In another aspect, the present disclosure provides a method for modifying a target nucleic acid locus of interest. The method may comprise delivering to the target nucleic acid locus any of the non-natural systems disclosed herein, including an enzyme and at least one synthetic guide RNA (sgRNA) disclosed herein. The enzyme may form a complex with the at least one sgRNA, and upon binding of the complex to the target nucleic acid locus of interest, may modify the target nucleic acid locus of interest. Delivering the enzyme to said locus may comprise transfecting a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise electroporating a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise incubating the system in a buffer with a nucleic acid comprising the locus of interest. In some cases, the target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). The target nucleic acid locus may comprise genomic DNA, viral DNA, viral RNA, or bacterial DNA. The target nucleic acid locus may be within a cell. The target nucleic acid locus may be in vitro.

The target nucleic acid locus may be within a eukaryotic cell or a prokaryotic cell. The cell may be an animal cell, a human cell, bacterial cell, archaeal cell, or a plant cell. The enzyme may induce a single or double-stranded break at or proximal to the target locus of interest.

[00154] In cases where the target nucleic acid locus may be within a cell, the enzyme may be supplied as a nucleic acid containing an open reading frame encoding the enzyme having a RuvC III domain having at least about 75% (e.g., at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%) identity to SEQ ID NOs: 46 or a functional variant thereof. In some cases, the nucleic acid comprises a promoter to which the open reading frame encoding the endonuclease is operably linked. The promoter may be a CMV, EFla, SV40, PGK1, Ubc, human beta actin, CAG, TRE, or CaMKIIa promoter. The endonuclease may be supplied as a capped mRNA containing said open reading frame encoding said endonuclease. The endonuclease may be supplied as a translated polypeptide. The at least one engineered sgRNA may be supplied as deoxyribonucleic acid (DNA) containing a gene sequence encoding said at least one engineered sgRNA operably linked to a ribonucleic acid (RNA) pol III promoter. In some cases, the organism may be eukaryotic. In some cases, the organism may be fungal. In some cases, the organism may be human.

[00155] MG4 enzymes [00156] In one aspect, the present disclosure provides for an engineered nuclease system comprising (a) an endonuclease. In some cases, the endonuclease is a Cas endonuclease. In some cases, the endonuclease is a Type II, Class II Cas endonuclease. The endonuclease may comprise a RuvC III domain, wherein said RuvC III domain has at least about 70% sequence identity to any one of SEQ ID NOs: 48-71 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain has at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% identity to any one of SEQ ID NOs: 48-71 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain is substantially identical to any one of SEQ ID NOs: 48-71 or a functional variant thereof.

[00157] The endonuclease may comprise an HNH domain having at least about 70% identity to any one of SEQ ID NOs: 92-115 or a functional variant thereof. In some cases, the endonuclease may comprise an HNH domain having at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical to any one of SEQ ID NOs: 92-115or a functional variant thereof. The endonuclease may comprise an HNH domain substantially identical to any one of SEQ ID NOs: 92-115 or a functional variant thereof.

[00158] In some cases, the endonuclease may comprise a variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 4-27 or a functional variant thereof . In some cases, the endonuclease may be substantially identical to any one of SEQ ID NOs: 4-27 or a functional variant thereof.

[00159] In some cases, the endonuclease may comprise a variant having one or more nuclear localization sequences (NLSs). The NLS may be proximal to the N- or C-terminus of said endonuclease. The NLS may be appended N-terminal or C-terminal to any one of SEQ ID NOs: 4-27, or to a functional variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 4-27. The NLS may be an SV40 large T antigen NLS. The NLS may be a c-myc NLS. The NLS can comprise a sequence with at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99% identity to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise a sequence substantially identical to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise any of the sequences in Table 1 or a combination thereof.

[00160] In some cases, sequence identity may be determined by the BLASTP, CLUSTALW, MUSCLE, MAFFT, Novafold, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. The sequence identity may be determined by the BLASTP algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and using a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

[00161] In some cases, the system above may comprise (b) at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease bearing a 5’ targeting region complementary to a desired cleavage sequence. In some cases, the 5’ targeting region may comprises a PAM sequence compatible with the endonuclease. In some cases, the 5’ most nucleotide of the targeting region may be G. In some cases, the 5’ targeting region may be 15-23 nucleotides in length. The guide sequence and the tracr sequence may be supplied as separate ribonucleic acids (RNAs) or a single ribonucleic acid (RNA). The guide RNA may comprise a crRNA tracrRNA binding sequence 3 ’ to the targeting region. The guide RNA may comprise a tracrRNA sequence preceded by a 4-nucleotide linker 3’ to the crRNA tracrRNA binding region. The sgRNA may comprise, from 5' to 3': a non-natural guide nucleic acid sequence capable of hybridizing to a target sequence in a cell; and a tracr sequence. In some cases, the non-natural guide nucleic acid sequence and the tracr sequence are covalently linked. [00162] In some cases, the tracr sequence may have a particular sequence. The tracr sequence may have at least about 80% to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of a natural tracrRNA sequence. The tracr sequence may have at least about 80% sequence identity to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of any one of SEQ ID NOs: 139-143 or a functional variant thereof. In some cases, the tracrRNA may be substantially identical to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of any one of SEQ ID NOs: 139-143 or a functional variant thereof. The tracrRNA may comprise any one of SEQ ID NOs: 139-143. [00163] In some cases, the at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease may comprise a sequence having at least about 80% identity to SEQ ID NO: 134 or a functional variant thereof. The sgRNA may comprise a sequence having at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 134 or a functional variant thereof. The sgRNA may comprise a sequence substantially identical to SEQ ID NO: 134 or a functional variant thereof.

[00164] In some cases, the system above may comprise two different sgRNAs or guide RNAs targeting a first region and a second region for cleavage in a target DNA locus, wherein the second region is 3’ to the first region. In some cases, the system above may comprise a single- or double-stranded DNA repair template comprising from 5’ to 3’ : a first homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 5’ to the first region, a synthetic DNA sequence of at least about 10 nucleotides, and a second homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 3’ to the second region.

[00165] In another aspect, the present disclosure provides a method for modifying a target nucleic acid locus of interest. The method may comprise delivering to the target nucleic acid locus any of the non-natural systems disclosed herein, including an enzyme and at least one synthetic guide RNA (sgRNA) disclosed herein. The enzyme may form a complex with the at least one sgRNA, and upon binding of the complex to the target nucleic acid locus of interest, may modify the target nucleic acid locus of interest. Delivering the enzyme to said locus may comprise transfecting a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise electroporating a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise incubating the system in a buffer with a nucleic acid comprising the locus of interest. In some cases, the target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). The target nucleic acid locus may comprise genomic DNA, viral DNA, viral RNA, or bacterial DNA. The target nucleic acid locus may be within a cell. The target nucleic acid locus may be in vitro.

[00166] In cases where the target nucleic acid locus may be within a cell, the enzyme may be supplied as a nucleic acid containing an open reading frame encoding the enzyme having a RuvC III domain having at least about 75% (e.g., at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%) identity to any one of SEQ ID NOs: 48- 71 or a functional variant thereof. In some cases, the nucleic acid comprises a promoter to which the open reading frame encoding the endonuclease is operably linked. The promoter may be a CMV, EFla, SV40, PGK1, Ubc, human beta actin, CAG, TRE, or CaMKIIa promoter. The endonuclease may be supplied as a capped mRNA containing said open reading frame encoding said endonuclease. The endonuclease may be supplied as a translated polypeptide. The at least one engineered sgRNA may be supplied as deoxyribonucleic acid (DNA) containing a gene sequence encoding said at least one engineered sgRNA operably linked to a ribonucleic acid (RNA) pol III promoter. In some cases, the organism may be eukaryotic. In some cases, the organism may be fungal. In some cases, the organism may be human.

[00167] MG6 enzymes

[00168] In one aspect, the present disclosure provides for an engineered nuclease system comprising (a) an endonuclease. In some cases, the endonuclease is a Cas endonuclease. In some cases, the endonuclease is a Type II, Class II Cas endonuclease. The endonuclease may comprise a RuvC III domain, wherein said RuvC III domain has at least about 70% sequence identity to any one of SEQ ID NOs: 72-83 or 246-253 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain has at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% identity to any one of SEQ ID NOs: 72-83 or 246-253 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain is substantially identical to any one of SEQ ID NOs: 72-83 or 246-253 or a functional variant thereof.

[00169] The endonuclease may comprise an HNH domain having at least about 70% identity to any one of SEQ ID NOs: 116-127 or 263-270 or a functional variant thereof. In some cases, the endonuclease may comprise a HNH domain having at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical to any one of SEQ ID NOs: 116-127 or 263-270 or a functional variant thereof. The endonuclease may comprise an HNH domain substantially identical to any one of SEQ ID NOs: 116-127 or 263-270 or a functional variant thereof.

[00170] In some cases, the endonuclease may comprise a variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 28-39 or 229-236 or a functional variant thereof . In some cases, the endonuclease may be substantially identical to any one of SEQ ID NOs: 28-39 or 229-236 or a functional variant thereof.

[00171] In some cases, the endonuclease may comprise a variant having one or more nuclear localization sequences (NLSs). The NLS may be proximal to the N- or C-terminus of said endonuclease. The NLS may be appended N-terminal or C-terminal to any one of SEQ ID NOs: 28-39 or 229-236, or to a functional variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 28-39 or 229-236. The NLS may be an SV40 large T antigen NLS. The NLS may be a c-myc NLS. The NLS can comprise a sequence with at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99% identity to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise a sequence substantially identical to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise any of the sequences in Table 1 or a combination thereof.

[00172] In some cases, sequence identity may be determined by the BLASTP, CLUSTALW, MUSCLE, MAFFT, Novafold, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. The sequence identity may be determined by the BLASTP algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and using a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

[00173] In some cases, the system above may comprise (b) at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease bearing a 5’ targeting region complementary to a desired cleavage sequence. In some cases, the 5’ targeting region may comprises a PAM sequence compatible with the endonuclease. In some cases, the 5’ most nucleotide of the targeting region may be G. In some cases, the 5’ targeting region may be 15-23 nucleotides in length. The guide sequence and the tracr sequence may be supplied as separate ribonucleic acids (RNAs) or a single ribonucleic acid (RNA). The guide RNA may comprise a crRNA tracrRNA binding sequence 3 ’ to the targeting region. The guide RNA may comprise a tracrRNA sequence preceded by a 4-nucleotide linker 3’ to the crRNA tracrRNA binding region. The sgRNA may comprise, from 5' to 3': a non-natural guide nucleic acid sequence capable of hybridizing to a target sequence in a cell; and a tracr sequence. In some cases, the non-natural guide nucleic acid sequence and the tracr sequence are covalently linked. [00174] In some cases, the tracr sequence may have a particular sequence. The tracr sequence may have at least about 80% to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of a natural tracrRNA sequence. The tracr sequence may have at least about 80% sequence identity to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of any one of SEQ ID NOs: 144-146 or a functional variant thereof. In some cases, the tracrRNA may be substantially identical to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of any one of SEQ ID NOs: 144-146 or a functional variant thereof. The tracrRNA may comprise any one of SEQ ID NOs: 144-146. [00175] In some cases, the at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease may comprise a sequence having at least about 80% identity to SEQ ID NO: 135 or a functional variant thereof. The sgRNA may comprise a sequence having at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 135 or a functional variant thereof. The sgRNA may comprise a sequence substantially identical to SEQ ID NO: 135 or a functional variant thereof. [00176] In some cases, the system above may comprise two different sgRNAs or guide RNAs targeting a first region and a second region for cleavage in a target DNA locus, wherein the second region is 3’ to the first region. In some cases, the system above may comprise a single- or double-stranded DNA repair template comprising from 5’ to 3’ : a first homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 5’ to the first region, a synthetic DNA sequence of at least about 10 nucleotides, and a second homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 3’ to the second region.

[00177] In another aspect, the present disclosure provides a method for modifying a target nucleic acid locus of interest. The method may comprise delivering to the target nucleic acid locus any of the non-natural systems disclosed herein, including an enzyme and at least one synthetic guide RNA (sgRNA) disclosed herein. The enzyme may form a complex with the at least one sgRNA, and upon binding of the complex to the target nucleic acid locus of interest, may modify the target nucleic acid locus of interest. Delivering the enzyme to said locus may comprise transfecting a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise electroporating a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise incubating the system in a buffer with a nucleic acid comprising the locus of interest. In some cases, the target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). The target nucleic acid locus may comprise genomic DNA, viral DNA, viral RNA, or bacterial DNA. The target nucleic acid locus may be within a cell. The target nucleic acid locus may be in vitro.

[00178] In cases where the target nucleic acid locus may be within a cell, the enzyme may be supplied as a nucleic acid containing an open reading frame encoding the enzyme having a RuvC III domain having at least about 75% (e.g., at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%) identity to any one of SEQ ID NOs: 72- 83 or 246-253 or a functional variant thereof. In some cases, the nucleic acid comprises a promoter to which the open reading frame encoding the endonuclease is operably linked. The promoter may be a CMV, EFla, SV40, PGK1, Ubc, human beta actin, CAG, TRE, or CaMKIIa promoter. The endonuclease may be supplied as a capped mRNA containing said open reading frame encoding said endonuclease. The endonuclease may be supplied as a translated polypeptide. The at least one engineered sgRNA may be supplied as deoxyribonucleic acid (DNA) containing a gene sequence encoding said at least one engineered sgRNA operably linked to a ribonucleic acid (RNA) pol III promoter. In some cases, the organism may be eukaryotic. In some cases, the organism may be fungal. In some cases, the organism may be human.

[00179] MG7 enzymes

[00180] In one aspect, the present disclosure provides for an engineered nuclease system comprising (a) an endonuclease. In some cases, the endonuclease is a Cas endonuclease. In some cases, the endonuclease is a Type II, Class II Cas endonuclease. The endonuclease may comprise a RuvC III domain, wherein said RuvC III domain has at least about 70% sequence identity to any one of SEQ ID NOs: 84-86 or 254-262 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain has at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% identity to any one of SEQ ID NOs: 84-86 or 254-262 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain is substantially identical to any one of SEQ ID NOs: 84-86 or 254-262 or a functional variant thereof.

[00181] The endonuclease may comprise an HNH domain having at least about 70% identity to any one of SEQ ID NOs: 128-130 or 271-279 or a functional variant thereof. In some cases, the endonuclease may comprise a HNH domain having at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical to any one of SEQ ID NOs: SEQ ID NOs: 128-130 or 271-279 or a functional variant thereof. The endonuclease may comprise an HNH domain substantially identical to any one of SEQ ID NOs: SEQ ID NOs: 128- 130 or 271-279 or a functional variant thereof.

[00182] In some cases, the endonuclease may comprise a variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 40-42 or 237-245 or a functional variant thereof . In some cases, the endonuclease may be substantially identical to any one of SEQ ID NOs: SEQ ID NOs: 40-42 or 237-245 or a functional variant thereof.

[00183] In some cases, the endonuclease may comprise a variant having one or more nuclear localization sequences (NLSs). The NLS may be proximal to the N- or C-terminus of said endonuclease. The NLS may be appended N-terminal or C-terminal to any one of SEQ ID NOs: 40-42 or 237-245, or to a functional variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 40-42 or 237-245. The NLS may be an SV40 large T antigen NLS. The NLS may be a c-myc NLS. The NLS can comprise a sequence with at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99% identity to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise a sequence substantially identical to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise any of the sequences in Table 1 or a combination thereof.

[00184] In some cases, sequence identity may be determined by the BLASTP, CLUSTALW, MUSCLE, MAFFT, Novafold, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. The sequence identity may be determined by the BLASTP algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and using a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

[00185] In some cases, the system above may comprise (b) at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease bearing a 5’ targeting region complementary to a desired cleavage sequence. In some cases, the 5’ targeting region may comprises a PAM sequence compatible with the endonuclease. In some cases, the 5’ most nucleotide of the targeting region may be G. In some cases, the 5’ targeting region may be 15-23 nucleotides in length. The guide sequence and the tracr sequence may be supplied as separate ribonucleic acids (RNAs) or a single ribonucleic acid (RNA). The guide RNA may comprise a crRNA tracrRNA binding sequence 3 ’ to the targeting region. The guide RNA may comprise a tracrRNA sequence preceded by a 4-nucleotide linker 3’ to the crRNA tracrRNA binding region. The sgRNA may comprise, from 5' to 3': a non-natural guide nucleic acid sequence capable of hybridizing to a target sequence in a cell; and a tracr sequence. In some cases, the non-natural guide nucleic acid sequence and the tracr sequence are covalently linked. [00186] In some cases, the tracr sequence may have a particular sequence. The tracr sequence may have at least about 80% to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of a natural tracrRNA sequence. The tracr sequence may have at least about 80% sequence identity to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of any one of SEQ ID NOs: 147 or 280 or a functional variant thereof.

In some cases, the tracrRNA may be substantially identical to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of any one of SEQ ID NOs: 147 or 280 or a functional variant thereof. The tracrRNA may comprise any one of SEQ ID NOs: 147 or 280. [00187] In some cases, the at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease may comprise a sequence having at least about 80% identity to SEQ ID NO: 136 or a functional variant thereof. The sgRNA may comprise a sequence having at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 136 or a functional variant thereof. The sgRNA may comprise a sequence substantially identical to SEQ ID NO: 136 or a functional variant thereof.

[00188] In some cases, the system above may comprise two different sgRNAs or guide RNAs targeting a first region and a second region for cleavage in a target DNA locus, wherein the second region is 3’ to the first region. In some cases, the system above may comprise a single- or double-stranded DNA repair template comprising from 5’ to 3’ : a first homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 5’ to the first region, a synthetic DNA sequence of at least about 10 nucleotides, and a second homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 3’ to the second region.

[00189] In another aspect, the present disclosure provides a method for modifying a target nucleic acid locus of interest. The method may comprise delivering to the target nucleic acid locus any of the non-natural systems disclosed herein, including an enzyme and at least one synthetic guide RNA (sgRNA) disclosed herein. The enzyme may form a complex with the at least one sgRNA, and upon binding of the complex to the target nucleic acid locus of interest, may modify the target nucleic acid locus of interest. Delivering the enzyme to said locus may comprise transfecting a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise electroporating a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise incubating the system in a buffer with a nucleic acid comprising the locus of interest. In some cases, the target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). The target nucleic acid locus may comprise genomic DNA, viral DNA, viral RNA, or bacterial DNA. The target nucleic acid locus may be within a cell. The target nucleic acid locus may be in vitro.

[00190] In cases where the target nucleic acid locus may be within a cell, the enzyme may be supplied as a nucleic acid containing an open reading frame encoding the enzyme having a RuvC III domain having at least about 75% (e.g., at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%) identity to any one of SEQ ID NOs: 84- 86 or 254-262 or a functional variant thereof. In some cases, the nucleic acid comprises a promoter to which the open reading frame encoding the endonuclease is operably linked. The promoter may be a CMV, EFla, SV40, PGK1, Ubc, human beta actin, CAG, TRE, or CaMKIIa promoter. The endonuclease may be supplied as a capped mRNA containing said open reading frame encoding said endonuclease. The endonuclease may be supplied as a translated polypeptide. The at least one engineered sgRNA may be supplied as deoxyribonucleic acid (DNA) containing a gene sequence encoding said at least one engineered sgRNA operably linked to a ribonucleic acid (RNA) pol III promoter. In some cases, the organism may be eukaryotic. In some cases, the organism may be fungal. In some cases, the organism may be human.

[00191] MG16 enzymes

[00192] In one aspect, the present disclosure provides for an engineered nuclease system comprising (a) an endonuclease. In some cases, the endonuclease is a Cas endonuclease. In some cases, the endonuclease is a Type II, Class II Cas endonuclease. The endonuclease may comprise a RuvC III domain, wherein said RuvC III domain has at least about 70% sequence identity to any one of SEQ ID NOs: 87-88 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain has at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99% identity to any one of SEQ ID NOs: 87-88 or a functional variant thereof. In some cases, the endonuclease may comprise a RuvC III domain, wherein the RuvC III domain is substantially identical to any one of SEQ ID NOs: 87-88 or a functional variant thereof.

[00193] The endonuclease may comprise an HNH domain having at least about 70% identity to any one of SEQ ID NOs: 131-132 or a functional variant thereof. In some cases, the endonuclease may comprise an HNH domain having at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identical to any one of SEQ ID NOs: 131-132 or a functional variant thereof. The endonuclease may comprise an HNH domain substantially identical to any one of SEQ ID NOs: 131-132 or a functional variant thereof.

[00194] In some cases, the endonuclease may comprise a variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 43-44 or a functional variant thereof . In some cases, the endonuclease may be substantially identical to any one of SEQ ID NOs: SEQ ID NOs: 43-44 or a functional variant thereof.

[00195] In some cases, the endonuclease may comprise a variant having one or more nuclear localization sequences (NLSs). The NLS may be proximal to the N- or C-terminus of said endonuclease. The NLS may be appended N-terminal or C-terminal to any one of SEQ ID NOs: 43-44, or to a functional variant having at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to any one of SEQ ID NOs: 43-44. The NLS may be an SV40 large T antigen NLS. The NLS may be a c-myc NLS. The NLS can comprise a sequence with at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99% identity to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise a sequence substantially identical to any one of SEQ ID NOs: 180-195 or a functional variant thereof. The NLS can comprise any of the sequences in Table 1 or a combination thereof.

[00196] In some cases, sequence identity may be determined by the BLASTP, CLUSTALW, MUSCLE, MAFFT, Novafold, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. The sequence identity may be determined by the BLASTP algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and using a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

[00197] In some cases, the system above may comprise (b) at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease bearing a 5’ targeting region complementary to a desired cleavage sequence. In some cases, the 5’ targeting region may comprises a PAM sequence compatible with the endonuclease. In some cases, the 5’ most nucleotide of the targeting region may be G. In some cases, the 5’ targeting region may be 15-23 nucleotides in length. The guide sequence and the tracr sequence may be supplied as separate ribonucleic acids (RNAs) or a single ribonucleic acid (RNA). The guide RNA may comprise a crRNA tracrRNA binding sequence 3 ’ to the targeting region. The guide RNA may comprise a tracrRNA sequence preceded by a 4-nucleotide linker 3’ to the crRNA tracrRNA binding region. The sgRNA may comprise, from 5' to 3': a non-natural guide nucleic acid sequence capable of hybridizing to a target sequence in a cell; and a tracr sequence. In some cases, the non-natural guide nucleic acid sequence and the tracr sequence are covalently linked. [00198] In some cases, the tracr sequence may have a particular sequence. The tracr sequence may have at least about 80% to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of a natural tracrRNA sequence. The tracr sequence may have at least about 80% sequence identity to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of SEQ ID NO: 148 or a functional variant thereof. In some cases, the tracrRNA may be substantially identical to at least about 60-100 (e.g., at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90) consecutive nucleotides of SEQ ID NO: 148 or a functional variant thereof. The tracrRNA may comprise SEQ ID NO: 148.

[00199] In some cases, the at least one engineered synthetic guide ribonucleic acid (sgRNA) capable of forming a complex with the endonuclease may comprise a sequence having at least about 80% identity to SEQ ID NO: 137 or a functional variant thereof. The sgRNA may comprise a sequence having at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99% identity to SEQ ID NO: 137 or a functional variant thereof. The sgRNA may comprise a sequence substantially identical to SEQ ID NO: 137 or a functional variant thereof.

[00200] In some cases, the system above may comprise two different sgRNAs or guide RNAs targeting a first region and a second region for cleavage in a target DNA locus, wherein the second region is 3’ to the first region. In some cases, the system above may comprise a single- or double-stranded DNA repair template comprising from 5’ to 3’ : a first homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 5’ to the first region, a synthetic DNA sequence of at least about 10 nucleotides, and a second homology arm comprising a sequence of at least about 20 (e.g., at least about 40, 80, 120, 150, 200, 300, 500, or lkb) nucleotides 3’ to the second region.

[00201] In another aspect, the present disclosure provides a method for modifying a target nucleic acid locus of interest. The method may comprise delivering to the target nucleic acid locus any of the non-natural systems disclosed herein, including an enzyme and at least one synthetic guide RNA (sgRNA) disclosed herein. The enzyme may form a complex with the at least one sgRNA, and upon binding of the complex to the target nucleic acid locus of interest, may modify the target nucleic acid locus of interest. Delivering the enzyme to said locus may comprise transfecting a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise electroporating a cell with the system or nucleic acids encoding the system. Delivering the nuclease to said locus may comprise incubating the system in a buffer with a nucleic acid comprising the locus of interest. In some cases, the target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). The target nucleic acid locus may comprise genomic DNA, viral DNA, viral RNA, or bacterial DNA. The target nucleic acid locus may be within a cell. The target nucleic acid locus may be in vitro.

[00202] In cases where the target nucleic acid locus may be within a cell, the enzyme may be supplied as a nucleic acid containing an open reading frame encoding the enzyme having a RuvC III domain having at least about 75% (e.g., at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%) identity to any one of SEQ ID NOs: 87- 88 or a functional variant thereof. In some cases, the nucleic acid comprises a promoter to which the open reading frame encoding the endonuclease is operably linked. The promoter may be a CMV, EFla, SV40, PGK1, Ubc, human beta actin, CAG, TRE, or CaMKIIa promoter. The endonuclease may be supplied as a capped mRNA containing said open reading frame encoding said endonuclease. The endonuclease may be supplied as a translated polypeptide. The at least one engineered sgRNA may be supplied as deoxyribonucleic acid (DNA) containing a gene sequence encoding said at least one engineered sgRNA operably linked to a ribonucleic acid (RNA) pol III promoter. In some cases, the organism may be eukaryotic. In some cases, the organism may be fungal. In some cases, the organism may be human.

EXAMPLES

Example 1. -Metagenomic analysis for new proteins

[00203] Metagenomic samples were collected from sediment and soil. Deoxyribonucleic acid (DNA) was extracted with a Zymobiomics DNA mini-prep kit and sequenced on an Illumina HiSeq® 2500. Where samples were collected, samples were collected with consent of property owners. Hidden Markov Models were generated based on known Cas protein sequences including type II Cas effector proteins and these models were used to search the metagenomic data. Novel effector proteins identified by the search were further screened for predicted activity by alignments to known proteins (see Figure 25). This metagenomic workflow resulted in MG1, MG2, MG4, MG6, MG7, and MG16 families of class II, type II CRISPR endonucleases described herein.

Example 2. - Discovery of An MG6 Family of CRISPR systems

[00204] Analysis of the data from the metagenomic analysis of Example 1 revealed a new cluster of previously undescribed putative CRISPR systems comprising six members (MG6-1, MG6-2, MG6-3, MG6-4, MG6-5, and MG6-6). The operon structure for this new family of systems is depicted in FIGURE 3. The corresponding protein and nucleic acid sequences for these new enzymes and their relevant subdomains are presented the sequence listing filed herewith. Based on their location relative to the other genes, putative tracrRNA sequences were identified in the operon and are presented in the sequence listing filed herewith. A detailed domain-level alignment of these sequences versus Cas9 as outlined in Shmakov et al. (Mol Cell. 2015 Nov 5;60(3):385-97.), which is entirely incorporated by reference here is depicted in Figures 4A-4C. Detailed domain level-alignment of MG6-1 through MG6-6 is presented in Figures 5A-5K. [00205] An additional comparison of MG6-1, MG6-2, MG6-3, MG6-4, MG6-5, and MG6-6 within the dataset revealed additional protein sequences with similar architecture, presented as SEQ NOs: 34-39.

Example 3.-Prophetic— Determination of Protospacer- Adjacent Motif.

[00206] Experiments are performed as in any of the examples in Karvelis et al. Methods. 2017 May 15; 121-122:3-8, which is entirely incorporated by reference here to identify the protospacer adjacent motif (PAM) sequence specificity for the novel enzymes described herein to allow for optimal synthetic sequence targeting.

[00207] In one example (in-vivo screen), cells bearing plasmids encoding any of the enzymes described herein and protospacer-targeting guide RNA are co-transformed with a plasmid library containing an antibiotic resistance gene, and a protospacer sequence flanked by a randomized PAM sequence. Plasmids containing functional PAMs are cleaved by the enzyme, leading to cell death. Deep-sequencing of the enzyme cleavage-resistant plasmid pool isolated from the surviving cells displays a set of depleted plasmids that contain functional cleavage- permitting PAMs.

[00208] In another example (in vitro screen), PAM library in the form of DNA plasmid or concatemeric repeats is subjected to cleavage by the RNP complex (e.g. including the enzyme, tracrRNA and crRNA or the enzyme and hybrid sgRNA) assembled in vitro or in cell lysates. Resulting free DNA ends resulting from successful cleavage events are captured by adapter ligation, followed by the PCR amplification of the PAM-sided products. Amplified library of functional PAMs is subjected to deep sequencing and PAMs licensing DNA cleavage are identified.

Example 4.-Prophetic — Use of synthetic CRISPR system as described herein in a mammalian cell for genome editing

[0001] DNA/RNA sequences encoding (i) an ORF encoding codon-optimized enzyme under a cell-compatible promoter with a cell-compatible C-terminal nuclear localization sequence (e.g. SV40 NLS in the case of human cells) and a suitable polyadenylation signal (e.g. TK pA signal in the case of human cells); and (ii) an ORF encoding an sgRNA (having a 5’ sequence beginning with G followed by 20 nt of a complementary targeting nucleic acid sequence targeting genomic DNA followed by a corresponding compatible PAM identified via Example 3 and a 3’ tracr-binding sequence, a linker, and the tracrRNA sequence) under a suitable Polymerase III promoter (e.g. the U6 promoter in mammalian cells) are prepared. In some embodiments, these sequences are prepared on the same or separate plasmid vectors, which are transfected via a suitable technique into eukaryotic cells. In some embodiments, these sequences are prepared as separate DNA sequences, which are transfected or microinjected into cells. In some embodiments, these sequences are prepared as synthesized RNAs or in-vitro transcribed RNAs which are transfected or microinjected into cells. In some embodiments, these sequences are translated into proteins and transfected or microinjected into cells.

[0002] Whichever transfection method is selected, (i) and (ii) are introduced into cells. A period of incubation is allowed to pass so that the enzyme and/or sgRNA can be transcribed and/or translated into active form. After the incubation period, genomic DNA in the vicinity of the targeting sequence is analyzed (e.g., by sequencing). An indel is introduced into the genomic DNA in the vicinity of the targeting sequence as a result of enzyme-mediated cleavage and non- homologous end joining.

[00209] In some embodiments, (i) and (ii) are introduced into cells with a third repair nucleotide that encodes regions of the genome flanking the cleavage site of sizes 25 bp or larger, which will facilitate homology directed repair. Containing within these flanking sequences may be a single base pair mutation, a functional gene fragment, a foreign or native gene for expression, or several genes composing a biochemical pathway.

Example 5.-Prophetic — Use of synthetic CRISPR system as described herein in vitro [00210] Any of the enzymes described herein are cloned into a suitable E. coli expression plasmid containing a purification tag and are recombinantly expressed in E. coli and purified using the recombinant tag. RNAs comprising a 5’ G followed by a 20 nt targeting sequence and PAM sequence, a tracrRNA binding region of a compatible crRNA, a GAAA linker, and a compatible tracrRNA are synthesized by suitable solid-phase RNA synthesis methods. Recombinant enzymes and sgRNA are combined in a suitable cleavage buffer containing Mg2+ (e.g., 20 mM HEPES pH 7.5, 100 mM KC1, 5 mM MgC12, 1 mM TCEPDTT, 5% glycerol) and the reaction is initiated by introducing a target DNA including a sequence complementary to the targeting sequence and PAM sequence. Cleavage of the DNA is monitored by a suitable assay (e.g., agarose gel electrophoresis followed by ethidium bromide (or similarly acting DNA- intercalating agent) staining and UV visualization).

Example 6.-(General protocol) PAM Sequence identification/confirmation for the endonucleases described herein [00211] PAM sequences were determined by sequencing plasmids containing randomly- generated PAM sequences that could be cleaved by putative endonucleases expressed in an E. coli lysate-based expression system (myTXTL, Arbor Biosciences). In this system, an E. coli codon optimized nucleotide sequence was transcribed and translated from a PCR fragment under control of a T7 promoter. A second PCR fragment with a tracr sequence under a T7 promoter and a minimal CRISPR array composed of a T7 promoter followed by a repeat-spacer-repeat sequence was transcribed in the same reaction. Successful expression of the endonuclease and tracr sequence in the TXTL system followed by CRISPR array processing provided active in vitro CRISPR nuclease complexes.

[00212] A library of target plasmids containing a spacer sequence matching that in the minimal array followed by 8N mixed bases (putative PAM sequences) was incubated with the output of the TXTL reaction. After 1-3 hr, the reaction was stopped and the DNA was recovered via a DNA clean-up kit, e.g., Zymo DCC, AMPure XP beads, QiaQuick etc. Adapter sequences were blunt-end ligated to DNA with active PAM sequences that had been cleaved by the endonuclease, whereas DNA that had not been cleaved was inaccessible for ligation. DNA segments comprising active PAM sequences were then amplified by PCR with primers specific to the library and the adapter sequence. The PCR amplification products were resolved on a gel to identify amplicons that corresponded to cleavage events. The amplified segments of the cleavage reaction were also used as template for preparation of an NGS library. Sequencing this resulting library, which was a subset of the starting 8N library, revealed the sequences which contain the correct PAM for the active CRISPR complex. For PAM testing with a single RNA construct, the same procedure was repeated except that an in vitro transcribed RNA was added along with the plasmid library and the tracr/minimal CRISPR array template was omitted. For endonucleases where NGS libraries were prepared, seqLogo (see e.g., Huber et al. Nat Methods. 2015 Feb; 12(2): 115-21) representations were constructed and are presented in Figures 17, 18, and 19. The seqLogo module used to construct these representations takes the position weight matrix of a DNA sequence motif (e.g. a PAM sequence) and plots the corresponding sequence logo as introduced by Schneider and Stephens (see e.g. Schneider et al. Nucleic Acids Res. 1990 Oct 25;18(20):6097-100. The characters representing the sequence in the seqLogo representations have been stacked on top of each other for each position in the aligned sequences (e.g. PAM sequences). The height of each letter is proportional to its frequency, and the letters have been sorted so the most common one is on top.

Example 7.-(General protocol) RNA Folding of tracrRNA and sgRNA structures [00213] Folded stmctures of guide RNA sequences at 37 °C were computed using the method of Andronescu et al. Bioinformatics. 2007 Jul l;23(13):il9-28, which is incorporated by reference herein in its entirety. Predicted structures of exemplary sgRNAs described herein are presented in Figures 15 and 16.

Example 8.-(General protocol) In vitro cleavage efficiency of MG CRISPR Complexes [00214] Endonucleases were expressed as His-tagged fusion proteins from an inducible

T7 promoter in a protease deficient E. coli B strain. Cells expressing the His-tagged proteins were lysed by soni cation and the His-tagged proteins were purified by Ni-NTA affinity chromatography on a HisTrap FF column (GE Lifescience) on an AKTA Avant FPLC (GE Lifescience). The eluate was resolved by SDS-PAGE on acrylamide gels (Bio-Rad) and stained with InstantBlue Ultrafast coomassie (Sigma- Aldrich). Purity was determined using densitometry of the protein band with ImageLab software (Bio-Rad). Purified endonucleases were dialyzed into a storage buffer composed of 50 mM Tris-HCl, 300 mM NaCl, 1 mM TCEP, 5% glycerol; pH 7.5 and stored at -80°C.

[00215] Target DNAs containing spacer sequences and PAM sequences (determined e.g., as in Example 6) were constructed by DNA synthesis. A single representative PAM was chosen for testing when the PAM had degenerate bases . The target DNAs comprised 2200 bp of linear DNA derived from a plasmid via PCR amplification with a PAM and spacer located 700 bp from one end. Successful cleavage resulted in fragments of 700 and 1500 bp. The target DNA, in vitro transcribed single RNA, and purified recombinant protein were combined in cleavage buffer (10 mM Tris, 100 mM NaCl, 10 mM MgCh) with an excess of protein and RNA and incubated for 5 minutes to 3 hours, usually 1 hr. The reaction was stopped via addition of RNAse A and incubation at 60 minutes. The reaction was then resolved on a 1.2% TAE agarose gel and the fraction of cleaved target DNA is quantified in ImageLab software.

Example 9.-(General protocol) Testing of Genome Cleavage Activity of MG CRISPR Complexes in E. coli

[00216] E. coli lacks the capacity to efficiently repair double-stranded DNA breaks. Thus, cleavage of genomic DNA can be a lethal event. Exploiting this phenomenon, endonuclease activity was tested in E. coli by recombinantly expressing an endonuclease and a tracrRNA in a target strain with spacer/target and PAM sequences integrated into its genomic DNA.

[00217] In this assay, the PAM sequence is specific for the endonuclease being tested as determined by the methods described in Example 6. sgRNA sequences were determined based upon the sequence and predicted structure of the tracrRNA. Repeat-anti -repeat pairings of 8-12 bp (generally lObp) were chosen, starting from the 5’ end of the repeat. The remaining 3’ end of the repeat and 5’ end of the tracrRNA were replaced with a tetraloop. Generally, the tetraloop was GAAA, but other tetraloops can be used, particularly if the GAAA sequence is predicted to interfere with folding. In these cases, a TTCG tetraloop was used.

[00218] Engineered strains with PAM sequences integrated into their genomic DNA were transformed with DNA encoding the endonuclease. Transformants were then made chemocompetent and transformed with 50 ng of single guide RNAs either specific to the target sequence (“on target”), or non-specific to the target (“off target”). After heat shock, transformations were recovered in SOC for 2 hrs at 37 °C. Nuclease efficiency was then determined by a 5-fold dilution series grown on induction media. Colonies were quantified from the dilution series in triplicate.

Example 10a.-(General protocol) Testing of Genome Cleavage Activity of MG CRISPR Complexes in Mammalian Cells

[00219] To confirm targeting and cleavage activity in mammalian cells, the MG Cas endonucleases were tested in two mammalian expression vectors: (a) one with a C-terminal SV40 NLS and a 2A-GFP tag, and (b) one with no GFP tag and two SV40 NLS sequences, one on the N-terminus and one on the C-terminus. In some instances, nucleotide sequences encoding the endonucleases were codon-optimized for expression in mammalian cells.

[00220] The corresponding single guide RNA sequence (sgRNA) with targeting sequence attached is cloned into a second mammalian expression vector. The two plasmids are cotransfected into HEK293T cells. 72 hr after co-transfection of the expression plasmid and a sgRNA targeting plasmid into HEK293T cells, the DNA is extracted and used for the preparation of an NGS-library. Percent NHEJ is measured via indels in the sequencing of the target site to demonstrate the targeting efficiency of the enzyme in mammalian cells. At least 10 different target sites were chosen to test each protein’s activity.

Example 10b. (General Protocol) Testing of Genome Cleavage Activity of MG CRISPR Complexes in Mammalian Cells

[00221] To show targeting and cleavage activity in mammalian cells, the MG Cas effector protein sequences were cloned into two mammalian expression vector: (a) one with flanking N and C-terminal SV40 NLS sequences, a C-terminal His tag, and a 2A-GFP tag at the C terminus after the His tag (Backbone 1), and (b) one with flanking NLS sequences and C-terminal His tag but no T2A GFP tag (Backbone 2). In some instances, nucleotide sequences encoding the endonucleases were the native sequence, codon-optimized for expression in E. coli, or codon- optimized for expression in mammalian cells.

[00222] The corresponding single guide RNA sequence (sgRNA) with targeting sequence attached was cloned into a second mammalian expression vector. The two plasmids were then cotransfected into HEK293T cells. 72 hr after co-transfection of the expression plasmid and a sgRNA targeting plasmid into HEK293T cells, the DNA was extracted and used for the preparation of an NGS-library. Percent NHEJ was measured via indels in the sequencing of the target site to demonstrate the targeting efficiency of the enzyme in mammalian cells. About 7-12 different target sites were chosen for testing each protein’s activity. An arbitrary threshold of 5% indels was used to identify active candidates.

Example 11.- Characterization of MG4 family members

PAM Specificity, tracrRNA/sgRNA Validation

[00223] The targeted endonuclease activity of MG4 family endonuclease systems was confirmed using the myTXTL system as described in Example 6. In this assay, PCR amplification of cleaved target plasmids yields a product that migrates at approximately 170 bp in the gel, as shown in Figures 6-9. Amplification products were observed for MG4-2 (dual guide: see gel2 lane 9, single guide: see gel 10 lane 7) (SEQ ID NO: 4). Sequencing the PCR products revealed active PAM sequence specificities for these endonucleases detailed in Table 2 below.

Table 2: PAM sequence specificities and related data for MG4 enzymes

[00224] Targeted endonuclease activity in mammalian cells

[00225] MG4-2 target loci were chosen to test locations in the genome with the PAM nGnCCC (SEQ ID NO: 155). The spacers corresponding to the chosen target sites were cloned into the sgRNA scaffold in the mammalian vector system backbone described in Example 10b. The sites are listed in Table 2a below. The activity of MG4-2 at various target sites is shown in Table 2a and Figure 20.

[00226] Table 2a: Activity of MG4-2 at various target sites

Example 12.- Characterization of MG6 family members [00227] PAM Specificity, tracrRNA/sgRNA Validation

[00228] The targeted endonuclease activity of MG6 family members was confirmed using the myTXTL system as described in Example 6. In this assay, PCR amplification of cleaved target plasmids yields a product that migrates at approximately 170 bp in the gel, as shown in Figures 6-9 Amplification products were observed for MG6-3 (dual guide: see gel 1 lane 2, single guide: see gel 2 lane 13) (SEQ ID NO: 28). Sequencing the PCR products revealed active PAM sequences specificities for these endonucleases detailed in Table 3 below.

Table 3: PAM sequence specificities and related data for MG6 enzymes

[00229] Targeted endonuclease activity in bacterial cells

[00230] In vivo activity of the MG6-3 endonuclease system (protein SEQ ID NO: 28; sgRNA SEQ ID NO: 135) was tested with the PAM sequence GAATAAGG as in Example 9 using a 22-nucleotide targeting sequence. Transformed E. coli were plated in serial dilution, and the results (showing E. coli serial dilutions in the top panel and quantitated growth in the bottom panel, where the right bar indicates non-targeting and the left bar indicates targeting sgRNA) are presented in Figure 10. A substantial reduction in the growth of E. coli expressing on target sgRNA compared to E. coli expressing non-target sgRNA indicates that genomic DNA was specifically cleaved by the MG6-3 endonuclease system.

[00231] Targeted endonuclease activity in mammalian cells

[00232] MG6-3 target loci were chosen to test locations in the genome with the PAM nRRTAA (SEQ ID NO: 156). The spacers corresponding to the chosen target sites were cloned into the sgRNA scaffold in the mammalian vector system backbone 1 described in Example 10b. The sites are listed in Table 3a below. The activity of MG6-3 at various target sites is shown in Table 3a and Figure 21.

[00233] Table 3a: Activity of MG6-3 at various target sites

Example 13.- Characterization of MG7 family members [00234] PAM Specificity, tracrRNA/sgRNA Validation

[00235] The targeted endonuclease activity of MG7 family endonuclease systems was confirmed using the myTXTL system as described in Example 6. In this assay, PCR amplification of cleaved target plasmids yields a product that migrates at approximately 170 bp in the gel, as shown in Figures 6-9. Amplification products were observed for MG7-1 (dual guide: see gel 5 lane 10; single guide: see gel 3 lane 7) (SEQ ID NO: 40). Sequencing the PCR products revealed active PAM sequences specificities for these endonucleases detailed in Table 4 below: Table 4: PAM sequence specificities and related data for MG7 enzymes

[00236] Targeted endonuclease activity in vitro

[00237] In vitro activity of the MG7-1 endonuclease system (protein SEQ ID NO: 40; sgRNA SEQ ID NO: 136) was tested with the PAM sequence TAGTCGGG using the method of Example 8 with a 22-nucleotide targeting sequence. The single guide sequence reported above (SEQ ID NO: 136) was used. The results are shown in Figure 11, which depicts a gel demonstrating DNA cleavage by MG7-1 in combination with targeting or non-targeting corresponding sgRNAs or the S. pyogenes sgRNA. The data demonstrated that 22 nucleotide targeting sequences were functional with the MG7-l/sgRNA system.

[00238] Targeted endonuclease activity in bacterial cells

[00239] In vivo activity of the MG7-1 endonuclease system (protein SEQ ID NO: 40) was tested with the PAM sequence TAGTCGGG as in Example 9 using a 22-nucleotide targeting sequence. Transformed E. coli were plated in serial dilution, and the results (showing E. coli serial dilutions in the top panel and quantitated growth in the bottom panel, where the right bar indicates non-targeting sgRNA and the left bar indicates targeting sgRNA) are presented in Figure 12. A substantial reduction in the growth of E. coli expressing on target sgRNA compared to E. coli expressing non-target sgRNA indicates that genomic DNA was specifically cleaved by the MG7-1 endonuclease system in E. coli cells.

[00240] Targeted endonuclease activity in mammalian cells (a)

[00241] The method of Example 10 was used to demonstrate targeting and cleavage activity in mammalian cells. Open reading frames encoding the MG7-1 (protein SEQ ID NO: 40) sequence was cloned into mammalian expression vectors. Three vectors were tested, one with a C-terminal SV40 NLS and a 2A-GFP tag (E. coli MG105-BB), one with no GFP tag and 2 NLS sequences, one on the N-terminus and one on the C-terminus (E. coli pMG5-BB), and one with codons optimized for human expression cloned into the 2-NLS plasmid backbone (MG7-lhs). The results of this experiment are shown in Figure 13 . The endonuclease expression vectors were cotransfected into HEK293T cells with a second vector for expressing the corresponding sgRNA comprising a guide sequence selected from Table 7. 72 hr after co transfection, the DNA was extracted and used for the preparation of an NGS-library. Cleavage activity was detected by the appearance of internal deletions (NHEJ remnants) in the vicinity of the target site. Results are presented in Figure 15.

Table 7: MG7-1 mammalian targeting sequences

[00242] Targeted endonuclease activity in mammalian cells (b)

[00243] MG7-1 target loci were chosen to test locations in the genome with the PAM nRRnC (SEQ ID NO: 153). The spacers corresponding to the chosen target sites were cloned into the sgRNA scaffold in the mammalian vector systems described in Example 10b. The sites are listed in Table 7a below. The activity of MG7-1 at various target sites is shown in Table 7a and Figure 22.

[00244] Table 7a: Activity of MG7-1 at various target sites

Example 14.- Characterization of MG16 family members [00245] PAM Specificity, tracrRNA/sgRNA Validation

[00246] The targeted endonuclease activity of MG16 family endonuclease systems was confirmed using the myTXTL system as described in Example 6. In this assay, PCR amplification of cleaved target plasmids yields a product that migrates at approximately 170 bp in the gel, as shown in Figures 6-9. Amplification products were observed for MG16-1 (dual guide: see gel 2 lane 4; single guide: see gel 3 lane 10) (SEQ ID NO: 43). Sequencing the PCR products revealed active PAM sequence specificities for these endonucleases detailed in Table 8 below. Table 8: PAM sequence specificities and related data for MG16 enzymes

[00247] Targeted endonuclease activity in bacterial cells

[00248] In vivo activity of the MG16-1 endonuclease system (protein SEQ ID NO: 43; sgRNA SEQ ID NO: 137) was tested with the PAM sequence TGGACCTG as in Example 9 using 22 nucleotide targeting sequence. Transformed E. coli were plated in serial dilution, and the results (showing E. coli serial dilutions in the top panel and quantitated growth in the bottom panel, where the right bar indicates non-targeting sgRNA and the left bar indicates targeting sgRNA) are presented in Figure 14. A substantial reduction in the growth of E. coli expressing on target sgRNA compared to E. coli expressing non-target sgRNA indicates that genomic DNA was specifically cleaved in E. coli cells by the MG 16-1 endonuclease system.

[00249] Targeted endonuclease activity in mammalian cells

[00250] MG16-1 target loci were chosen to test locations in the genome with the PAM nGGnCC (SEQ ID NO: 281). The spacers corresponding to the chosen target sites were cloned into the sgRNA scaffold in the mammalian vector systems described in Example 10b. The sites are listed in Table 8a below. The activity of MG16-1 at various target sites is shown in Table 8a and Figure 23.

[00251] Table 8a: Activity of MG16-1 at various target sites

Example 15.- Characterization of MG2 family members [00252] PAM Specificity, tracrRNA/sgRNA Validation

[00253] The targeted endonuclease activity of MG2 family members was confirmed using the myTXTL system as described in Example 6. In this assay, PCR amplification of cleaved target plasmids yields a product that migrates at approximately 170 bp in the gel, as shown in Figures 6-9. In the assay shown in Figures 6-9, active proteins that successfully cleave the library result in a band around 170 bp in the gel. Amplification products were observed for MG2-4 (dual guide: see gel 1 lane 7, single guide: gel 8 lane 8 and gel 8 lane 9) (SEQ ID NO:

2). Sequencing the PCR products revealed active PAM sequences specificities for these endonucleases detailed in Table 9 below.

Table 9: PAM sequence specificities and related data for MG2 enzymes

EMBODIMENTS

[00254] The following embodiments are illustrative nature and are not intended to be limiting in any way.

1. An engineered nuclease system comprising:

(a) an endonuclease comprising a RuvC III domain and an HNH domain, wherein said endonuclease is derived from an uncultivated microorganism, and wherein said endonuclease is a class 2, type II Cas endonuclease; and

(b) an engineered guide ribonucleic acid structure configured to form a complex with said endonuclease comprising: i. a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and ii. a tracr ribonucleic acid sequence configured to bind to said endonuclease.

2. The engineered nuclease system of embodiment 1, wherein said RuvC III domain comprises a sequence with at least 70%, at least 75%, at least 80% or at least 90% sequence identity to any one of SEQ ID NOs: 45-88 or SEQ ID NOs: 246-262.

3. An engineered nuclease system comprising:

(a) an endonuclease comprising a RuvC III domain having at least 75% sequence identity to any one of SEQ ID NOs: 45-88 or SEQ ID NOs: 246-262; and

4. An engineered nuclease system comprising: (a) an endonuclease configured to bind to a protospacer adjacent motif (PAM) sequence comprising SEQ ID NOs: 149-158, wherein said endonuclease is a class 2, type II Cas endonuclease; and

5. The engineered nuclease system of embodiment 4, wherein said endonuclease is not a Cas9 endonuclease, a Cas 14 endonuclease, a Cas 12a endonuclease, a Cas 12b endonuclease, a Cas 12c endonuclease, a Cas 12d endonuclease, a Casl2e endonuclease, a Casl3a endonuclease, a Cas 13b endonuclease, a Cas 13c endonuclease, or a Cas 13d endonuclease.

6. The engineered nuclease system of embodiment 4, wherein said endonuclease has less than 80% identity to a Cas9 endonuclease.

7. The engineered nuclease system of any one of embodiments 3-6, wherein said endonuclease further comprises an HNH domain.

8. The engineered nuclease system of any one of embodiments 1-7, wherein said tracr ribonucleic acid sequence comprises a sequence with at least 80% sequence identity to about 60 to 90 consecutive nucleotides selected from any one of SEQ ID NOs: 138-148 or SEQ ID NO: 280.

9. An engineered nuclease system comprising,

(a) an engineered guide ribonucleic acid structure comprising: a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and a tracr ribonucleic acid sequence configured to bind to an endonuclease, wherein said tracr ribonucleic acid sequence comprises a sequence with at least 80% sequence identity to about 60 to 90 consecutive nucleotides selected from any one of

SEQ ID NOs: 138-148 or SEQ ID NO: 280; and

(b) a class 2, type II Cas endonuclease configured to bind to said engineered guide ribonucleic acid.

10. The engineered nuclease system of any of embodiments 1-3 or 9, wherein said endonuclease is configured to bind to a protospacer adjacent motif (PAM) sequence selected from the group comprising SEQ ID NOs: 149-158.

11. The engineered nuclease system of any one of embodiments 1-9, wherein said engineered guide ribonucleic acid structure comprises at least two ribonucleic acid polynucleotides.

12. The engineered nuclease system of any one of embodiments 1-9, wherein said engineered guide ribonucleic acid structure comprises one ribonucleic acid polynucleotide comprising said guide ribonucleic acid sequence and said tracr ribonucleic acid sequence.

13. The engineered nuclease system of any one of embodiments 1-12, wherein said guide ribonucleic acid sequence is complementary to a prokaryotic, bacterial, eukaryotic, fungal, plant, mammalian, or human genomic sequence.

14. The engineered nuclease system of any one of embodiments 1-13, wherein said guide ribonucleic acid sequence is 15-23 nucleotides in length.

15. The engineered nuclease system of any one of embodiments 1-14, wherein said endonuclease comprises one or more nuclear localization sequences (NLSs) proximal to an N- or C-terminus of said endonuclease. 16. The engineered nuclease system of any one of embodiments 1-15, wherein said NLS comprises a sequence selected from the group consisting of SEQ ID NO: 180-195.

17. The engineered nuclease system of any one of embodiments 1-16, further comprising (c) a single- or double-stranded DNA repair template comprising from 5' to 3': a first homology arm comprising a sequence of at least 20 nucleotides 5' to said target deoxyribonucleic acid sequence, a synthetic DNA sequence of at least 10 nucleotides, and a second homology arm comprising a sequence of at least 20 nucleotides 3' to said target sequence.

18. The engineered nuclease system of embodiment 17, wherein said first or second homology arm comprises a sequence of at least 40, 80, 120, 150, 200, 300, 500, or 1,000 nucleotides.

19. The engineered nuclease system of any one of embodiments 1-18, wherein said system further comprises a source of Mg²⁺

20. The engineered nuclease system of any one of embodiments 1-19, wherein said endonuclease and said tracr ribonucleic acid sequence are derived from distinct bacterial species within a same phylum.

21. The engineered nuclease system of any one of embodiments 1-20, wherein said endonuclease is derived from a bacterium belonging to genus Dermabacter.

22. The engineered nuclease system of any one of embodiments 1-20, wherein said endonuclease is derived from a bacterium belonging to Phylum Verrucomicrobia, Phylum Candidatus Peregrinibacteria, or Phylum Candidatus Melainabacteria.

23. The engineered nuclease system of any one of embodiments 1-22, wherein said HNH domain comprises a sequence with at least 70% or at least 80% identity to any one of SEQ ID NOs: 89-132 or SEQ ID NOs: 263-279. 24. The engineered nuclease system of any one of embodiments 1-23, wherein said endonuclease comprises SEQ ID NOs: 1-44 or SEQ ID NOs: 229-245, or SEQ ID NOs: 292-293 or a variant thereof having at least 55% identity thereto.

25. The engineered nuclease system of any one of embodiments 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 46 or SEQ ID NOs: 46-47.

26. The engineered nuclease system of any one of embodiments 1-25, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 90 or SEQ ID NOs: 90-91.

27. The engineered nuclease system of any one of embodiments 1-26, wherein said endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NOs: 214-221.

28. The engineered nuclease system of any one of embodiments 1-27, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 2 or SEQ ID NOs: 2-3.

29. The engineered nuclease system of any one of embodiments 1-28, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 138 or SEQ ID NO: 133.

30. The engineered nuclease system of any one of embodiments 1-29, wherein said guide RNA structure comprises a tracr ribonucleic acid sequence comprising a hairpin comprising at least 8, at least 10, or at least 12 base-paired ribonucleotides. 31. The engineered nuclease system of any one of embodiments 1-30, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 149 and SEQ ID NO: 154.

32. The engineered nuclease system of any one of embodiments 1-31, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 46; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 133 or SEQ ID NO: 138; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 149 or SEQ ID NO: 154.

33. The engineered nuclease system of any one of embodiments 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 48 or SEQ ID NOs: 48-71.

34. The engineered nuclease system of any one of embodiments 1-24 or embodiment 33, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 92 or SEQ ID NOs: 92-115.

35. The engineered nuclease system of any one of embodiments 1-24 or embodiments 33-34, wherein said endonuclease comprises SEQ ID NO: 222.

36. The engineered nuclease system of any one of embodiments 1-24 or embodiments 33-35, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 4 or SEQ ID NOs: 4-27.

37. The engineered nuclease system of any one of embodiments 1-24 or embodiments 33-36, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 139, SEQ ID NOs: 139-143, or SEQ ID NO: 134. 38. The engineered nuclease system of any one of embodiments 1-24 or embodiments 33-37, wherein said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 150 or SEQ ID NO: 155.

39. The engineered nuclease system of any one of embodiments 1-24 or embodiment 33- 38, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 48; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 134 or SEQ ID NO: 139; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 150 or SEQ ID NO: 155.

40. The engineered nuclease system of any one of embodiments 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 72, SEQ ID NOs: 72-83, and SEQ ID NOs: 246-253.

41. The engineered nuclease system of any one of embodiments 1-24 or embodiment 40, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 116, SEQ ID NOs: 116-127, and SEQ ID NOs: 263-270.

42. The engineered nuclease system of any one of embodiments 1-24 or embodiments 40-41, wherein said endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NO: 223-225.

43. The engineered nuclease system of any one of embodiments 1-24 or embodiments 40-42, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 28, SEQ ID NOs: 28-39, and SEQ ID NOs: 229-236.

44. The engineered nuclease system of any one of embodiments 1-24 or embodiments 40-43, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 144, SEQ ID NOs: 144-146, and SEQ ID NO: 135.

45. The engineered nuclease system of any one of embodiments 1-24 or embodiments 40-44, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 151 and SEQ ID NO: 156.

46. The engineered nuclease system of any one of embodiments 1-24 or embodiment 40- 45, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 72; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 135 or SEQ ID NO: 144; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 151 or SEQ ID NO: 156.

47. The engineered nuclease system of any one of embodiments 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 84, SEQ ID NOs: 84-86, and SEQ ID NOs: 254-262.

48. The engineered nuclease system of any one of embodiments 1-24 or embodiment 47, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 128, SEQ ID NOs: 128-130, and SEQ ID NOs: 271-279.

49. The engineered nuclease system of any one of embodiments 1-24 or embodiments 47-48, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 40, SEQ ID NOs: 40-42, and SEQ ID NOs: 237-245.

50. The engineered nuclease system of any one of embodiments 1-24 or embodiments 47-49, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 147, SEQ ID NO: 280, or SEQ ID NO: 136.

51. The engineered nuclease system of any one of embodiments 1-24 or embodiments 47-50, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 152 and SEQ ID NO: 157.

52. The engineered nuclease system of any one of embodiments 1-24 or embodiment 47- 51, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 84; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 136 or SEQ ID NO: 147; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 152 or SEQ ID NO: 157.

53. The engineered nuclease system of any one of embodiments 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 87, or SEQ ID NOs: 87-88.

54. The engineered nuclease system of any one of embodiments 1-24 or embodiment 53, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 131 or SEQ ID NOs: 131-132.

55. The engineered nuclease system of any one of embodiments 1-24 or embodiments 53-54, wherein said endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NO: 226-228. 56. The engineered nuclease system of any one of embodiments 1-24 or embodiments 53-55, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 43 or SEQ ID NOs: 43-44.

57. The engineered nuclease system of any one of embodiments 1-24 or embodiments 53-56, wherein said guide RNA structure comprises a tracr ribonucleic acid sequence comprising at least two hairpins comprising less than 5 base-paired ribonucleotides.

58. The engineered nuclease system of any one of embodiments 1-24 or embodiments 53-57, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 148 or SEQ ID NO: 137.

59. The engineered nuclease system of any one of embodiments 1-24 or embodiments 53-58, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 153 and SEQ ID NO: 158.

60. The engineered nuclease system of any one of embodiments 1-24 or embodiment 53- 59, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 87; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 137 or SEQ ID NO: 148; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 153 or SEQ ID NO: 158.

61. The engineered nuclease system of any one of embodiments 1-60, wherein said sequence identity is determined by a BLASTP, CLUSTALW, MUSCLE, MAFFT, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm. 62. The engineered nuclease system of embodiment 61, wherein said sequence identity is determined by said BLASTP homology search algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

63. An engineered guide ribonucleic acid polynucleotide comprising: a) a DNA-targeting segment comprising a nucleotide sequence that is complementary to a target sequence in a target DNA molecule; and b) a protein-binding segment comprising two complementary stretches of nucleotides that hybridize to form a double-stranded RNA (dsRNA) duplex, wherein said two complementary stretches of nucleotides are covalently linked to one another with intervening nucleotides, and wherein said engineered guide ribonucleic acid polynucleotide is capable of forming a complex with an endonuclease comprising a RuvC III domain having at least 75% sequence identity to any one of SEQ ID NOs: 45-88 or SEQ ID NOs: 246-262 and targeting said complex to said target sequence of said target DNA molecule.

64. The engineered guide ribonucleic acid polynucleotide of embodiment 63, wherein said DNA-targeting segment is positioned 5' of both of said two complementary stretches of nucleotides.

65. The engineered guide ribonucleic acid polynucleotide of any of embodiments 63-64, wherein: a) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 138; b) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 139 or SEQ ID NOs: 139-143; c) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 144 or SEQ ID NOs: 144-146; d) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 147; or e) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 148.

66. The engineered guide ribonucleic acid polynucleotide of any of embodiment 63-65, wherein: a) said guide ribonucleic acid polynucleotide comprises a tracr ribonucleic acid comprising a hairpin comprising at least 8, at least 10, or at least 12 base-paired ribonucleotides; or b) said guide ribonucleic acid polynucleotide comprises a tracr ribonucleic acid sequence comprising at least two hairpins comprising less than 5 base-paired ribonucleotides.

67. A deoxyribonucleic acid polynucleotide encoding the engineered guide ribonucleic acid polynucleotide of any one of embodiments 63-66.

68. A nucleic acid comprising an engineered nucleic acid sequence optimized for expression in an organism, wherein said nucleic acid encodes an endonuclease comprising a RuvC III domain and an HNH domain, wherein said endonuclease is a class 2, type II Cas endonuclease, and wherein said endonuclease is derived from an uncultivated microorganism.

69. A nucleic acid comprising an engineered nucleic acid sequence optimized for expression in an organism, wherein said nucleic acid encodes an endonuclease comprising a RuvC III domain having at least 70% sequence identity to any one of SEQ ID NOs: 45-88. 70. The nucleic acid of any one of embodiments 68-69, wherein said endonuclease comprises an HNH domain having at least 70% or at least 80% sequence identity to any one of SEQ ID NOs: 89-132.

71. The nucleic acid of any one of embodiments 68-70, wherein said endonuclease comprises SEQ ID NOs: 170-179 or a variant thereof having at least 70% sequence identity thereto.

72. The nucleic acid of any one of embodiments 68-71, wherein said endonuclease comprises a sequence encoding one or more nuclear localization sequences (NLSs) proximal to an N- or C-terminus of said endonuclease.

73. The nucleic acid of embodiment 72, wherein said NLS comprises a sequence selected from SEQ ID NOs: 180-195.

74. The nucleic acid of any one of embodiments 68-73, wherein said organism is prokaryotic, bacterial, eukaryotic, fungal, plant, mammalian, rodent, or human.

75. The nucleic acid of embodiment 74, wherein said organism is E. coli, and wherein: a) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

170; b) said nucleic acid sequence has at least 70%, 80%, or 90% identity to a sequence selected from the group consisting of SEQ ID NOs: 171-172; c) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

173; d) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 174; or e) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

175.

76. The nucleic acid of embodiment 74, wherein said organism is human, and wherein: a) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

176; b) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

177; c) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

178; or d) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

179.

77. A vector comprising a nucleic acid sequence encoding a class 2, type II Cas endonuclease comprising a RuvC III domain and an HNH domain, wherein said endonuclease is derived from an uncultivated microorganism.

78. A vector comprising the nucleic acid of any of embodiments 68-76.

79. The vector of any of embodiments 77-78, further comprising a nucleic acid encoding an engineered guide ribonucleic acid structure configured to form a complex with said endonuclease comprising: a) a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and b) a tracr ribonucleic acid sequence configured to bind to said endonuclease.

80. The vector of any of embodiments 77-79, wherein the vector is a plasmid, a minicircle, a CELiD, an adeno-associated virus (AAV) derived virion, or a lentivirus.

81. A cell comprising the vector of any of embodiments 77-80.

82. A method of manufacturing an endonuclease, comprising cultivating said cell of embodiment 81. 83. A method for binding, cleaving, marking, or modifying a double-stranded deoxyribonucleic acid polynucleotide, comprising:

(c) contacting said double-stranded deoxyribonucleic acid polynucleotide with a class 2, type II Cas endonuclease in complex with an engineered guide ribonucleic acid structure configured to bind to said endonuclease and said double-stranded deoxyribonucleic acid polynucleotide;

(d) wherein said double-stranded deoxyribonucleic acid polynucleotide comprises a protospacer adjacent motif (PAM); and

(e) wherein said PAM comprises a sequence selected from the group consisting of SEQ ID NOs: 149-153 or SEQ ID NOs: 154-158.

84. The method of embodiment 83, wherein said double-stranded deoxyribonucleic acid polynucleotide comprises a first strand comprising a sequence complementary to a sequence of said engineered guide ribonucleic acid structure and a second strand comprising said PAM.

85. The method of embodiment 84, wherein said PAM is directly adjacent to the 3' end of said sequence complementary to said sequence of said engineered guide ribonucleic acid structure.

86. The method of any one of embodiments 82-85, wherein said class 2, type II Cas endonuclease is not a Cas9 endonuclease, a Casl4 endonuclease, a Casl2a endonuclease, a Cas 12b endonuclease, a Cas 12c endonuclease, a Cas 12d endonuclease, a Casl2e endonuclease, a Casl3a endonuclease, a Cas 13b endonuclease, a Cas 13c endonuclease, or a Cas 13d endonuclease.

87. The method of any one of embodiments 82-86, wherein said class 2, type II Cas endonuclease is derived from an uncultivated microorganism.

88. The method of any one of embodiments 82-87, wherein said double-stranded deoxyribonucleic acid polynucleotide is a eukaryotic, plant, fungal, mammalian, rodent, or human double-stranded deoxyribonucleic acid polynucleotide. 89. The method of any one of embodiments 82-88, wherein: a) said PAM comprises SEQ ID NO: 149 or SEQ ID NO: 154; b) said PAM comprises SEQ ID NO: 150 or SEQ ID NO: 155; c) said PAM comprises SEQ ID NO: 151 or SEQ ID NO: 156; d) said PAM comprises SEQ ID NO: 152 or SEQ ID NO: 157; or e) said PAM comprises SEQ ID NO: 153 or SEQ ID NO: 158.

90. A method of modifying a target nucleic acid locus, said method comprising delivering to said target nucleic acid locus said engineered nuclease system of any one of embodiments 1-62, wherein said endonuclease is configured to form a complex with said engineered guide ribonucleic acid structure, and wherein said complex is configured such that upon binding of said complex to said target nucleic acid locus, said complex modifies said target nucleic acid locus.

91. The method of embodiment 89, wherein modifying said target nucleic acid locus comprises binding, nicking, cleaving, or marking said target nucleic acid locus.

92. The method of any of embodiments 89-91, wherein said target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA).

93. The method of embodiment 92, wherein said target nucleic acid comprises genomic DNA, viral DNA, viral RNA, or bacterial DNA.

94. The method of any one of embodiments 89-93, wherein said target nucleic acid locus is in vitro.

95. The method of any one of embodiments 89-93, wherein said target nucleic acid locus is within a cell. 96. The method of embodiment 95, wherein said cell is a prokaryotic cell, a bacterial cell, a eukaryotic cell, a fungal cell, a plant cell, an animal cell, a mammalian cell, a rodent cell, a primate cell, or a human cell.

97. The method of any one of embodiments 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering the nucleic acid of any of embodiments 68-73 or the vector of any of embodiments 77-79.

98. The method of any one of embodiments 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a nucleic acid comprising an open reading frame encoding said endonuclease.

99. The method of embodiment 97, wherein said nucleic acid comprises a promoter to which said open reading frame encoding said endonuclease is operably linked.

100. The method of any one of embodiments 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a capped mRNA containing said open reading frame encoding said endonuclease.

101. The method of any one of embodiments 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a translated polypeptide.

102. The method of any one of embodiments 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a deoxyribonucleic acid (DNA) encoding said engineered guide ribonucleic acid structure operably linked to a ribonucleic acid (RNA) pol III promoter.

103. The method of any one of embodiments 89-102, wherein said endonuclease induces a single-stranded break or a double-stranded break at or proximal to said target locus. [00255] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

WHAT IS CLAIMED IS:

1. An engineered nuclease system comprising:

2. The engineered nuclease system of claim 1, wherein said RuvC III domain comprises a sequence with at least 70%, at least 75%, at least 80% or at least 90% sequence identity to any one of SEQ ID NOs: 45-88 or SEQ ID NOs: 246-262.

3. An engineered nuclease system comprising:

4. An engineered nuclease system comprising: (a) an endonuclease configured to bind to a protospacer adjacent motif (PAM) sequence comprising any one of SEQ ID NOs: 149-158 or 294-296, wherein said endonuclease is a class 2, type II Cas endonuclease; and

5. The engineered nuclease system of claim 4, wherein said endonuclease is not a Cas9 endonuclease, a Cas 14 endonuclease, a Cas 12a endonuclease, a Cas 12b endonuclease, a Cas 12c endonuclease, a Cas 12d endonuclease, a Casl2e endonuclease, a Casl3a endonuclease, a

Cas 13b endonuclease, a Cas 13c endonuclease, or a Cas 13d endonuclease.

6. The engineered nuclease system of claim 4, wherein said endonuclease has less than 80% identity to a Cas9 endonuclease.

7. The engineered nuclease system of any one of claims 3-6, wherein said endonuclease further comprises an HNH domain.

8. The engineered nuclease system of any one of claims 1-7, wherein said tracr ribonucleic acid sequence comprises a sequence with at least 80% sequence identity any one of SEQ ID NOs: 138-148 or SEQ ID NO: 280.

9. An engineered nuclease system comprising,

(a) an engineered guide ribonucleic acid structure comprising: a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and a tracr ribonucleic acid sequence configured to bind to an endonuclease, wherein: (i) said tracr ribonucleic acid sequence comprises a sequence with at least 80% sequence identity to any one of SEQ ID NOs: 138-148 or SEQ ID NO: 280, or (ii) said engineered guide ribonucleic acid structure comprises a sequence having at least 80%, at least 82%, at least 84%, at least 86%, at least 88%, at least 90%, at least 91%, at least

92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to SEQ ID NO: 297; and

10. The engineered nuclease system of any of claims 1-3 or 9, wherein said endonuclease is configured to bind to a protospacer adjacent motif (PAM) sequence selected from the group consisting of SEQ ID NOs: 149-158 and 294-296.

11. The engineered nuclease system of any one of claims 1-9, wherein said engineered guide ribonucleic acid structure comprises at least two ribonucleic acid polynucleotides.

12. The engineered nuclease system of any one of claims 1-9, wherein said engineered guide ribonucleic acid structure comprises one ribonucleic acid polynucleotide comprising said guide ribonucleic acid sequence and said tracr ribonucleic acid sequence.

13. The engineered nuclease system of any one of claims 1-12, wherein said guide ribonucleic acid sequence is complementary to a prokaryotic, bacterial, eukaryotic, fungal, plant, mammalian, or human genomic sequence.

14. The engineered nuclease system of any one of claims 1-13, wherein said guide ribonucleic acid sequence is 15-23 nucleotides in length.

15. The engineered nuclease system of any one of claims 1-14, wherein said endonuclease comprises one or more nuclear localization sequences (NLSs) proximal to an N- or C-terminus of said endonuclease.

16. The engineered nuclease system of any one of claims 1-15, wherein said NLS comprises a sequence selected from the group consisting of SEQ ID NO: 180-195.

17. The engineered nuclease system of any one of claims 1-16, further comprising

(c) a single- or double-stranded DNA repair template comprising from 5' to 3': a first homology arm comprising a sequence of at least 20 nucleotides 5' to said target deoxyribonucleic acid sequence, a synthetic DNA sequence of at least 10 nucleotides, and a second homology arm comprising a sequence of at least 20 nucleotides 3' to said target sequence.

18. The engineered nuclease system of claim 17, wherein said first or second homology arm comprises a sequence of at least 40, 80, 120, 150, 200, 300, 500, or 1,000 nucleotides.

19. The engineered nuclease system of any one of claims 1-18, wherein said system further comprises a source of Mg²⁺

20. The engineered nuclease system of any one of claims 1-19, wherein said endonuclease and said tracr ribonucleic acid sequence are derived from distinct bacterial species within a same phylum.

21. The engineered nuclease system of any one of claims 1-20, wherein said endonuclease is derived from a bacterium belonging to genus Dermabacter.

22. The engineered nuclease system of any one of claims 1-20, wherein said endonuclease is derived from a bacterium belonging to Phylum Verrucomicrobia, Phylum Candidatus Peregrinibacteria, or Phylum Candidatus Melainabacteria.

23. The engineered nuclease system of any one of claims 1-22, wherein said HNH domain comprises a sequence with at least 70% or at least 80% identity to any one of SEQ ID NOs: 89-132 or SEQ ID NOs: 263-279.

24. The engineered nuclease system of any one of claims 1-23, wherein said endonuclease comprises SEQ ID NOs: 1-44 or SEQ ID NOs: 229-245 or a variant thereof having at least 55% identity thereto.

25. The engineered nuclease system of any one of claims 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 46 or SEQ ID NOs: 46-47.

26. The engineered nuclease system of any one of claims 1-25, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 90 or SEQ ID NOs: 90-91.

27. The engineered nuclease system of any one of claims 1-26, wherein said endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NOs: 214-221.

28. The engineered nuclease system of any one of claims 1-27, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 2 or SEQ ID NOs: 2-3.

29. The engineered nuclease system of any one of claims 1-28, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 138 or SEQ ID NO: 133.

30. The engineered nuclease system of any one of claims 1-29, wherein said guide RNA structure comprises a tracr ribonucleic acid sequence comprising a hairpin comprising at least 8, at least 10, or at least 12 base-paired ribonucleotides.

31. The engineered nuclease system of any one of claims 1-30, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 149 and SEQ ID NO: 154.

32. The engineered nuclease system of any one of claims 1-31, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 46; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 133 or SEQ ID NO: 138; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 149 or SEQ ID NO: 154.

33. The engineered nuclease system of any one of claims 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 48 or SEQ ID NOs: 48-71.

34. The engineered nuclease system of any one of claims 1-24 or claim 33, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 92 or SEQ ID NOs: 92-115.

35. The engineered nuclease system of any one of claims 1-24 or claims 33-34, wherein said endonuclease comprises SEQ ID NO: 222.

36. The engineered nuclease system of any one of claims 1-24 or claims 33-35, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 4 or SEQ ID NOs: 4-27.

37. The engineered nuclease system of any one of claims 1-24 or claims 33-36, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 139, SEQ ID NOs: 139-143, or SEQ ID NO: 134.

38. The engineered nuclease system of any one of claims 1-24 or claims 33-37, wherein said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 150 or SEQ ID NO: 155.

39. The engineered nuclease system of any one of claims 1-24 or claim 33-38, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 48; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 134 or SEQ ID NO: 139; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 150 or SEQ ID NO: 155.

40. The engineered nuclease system of any one of claims 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 72, SEQ ID NOs: 72-83, and SEQ ID NOs: 246-253.

41. The engineered nuclease system of any one of claims 1-24 or claim 40, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 116, SEQ ID NOs: 116-127, and SEQ ID NOs: 263- 270.

42. The engineered nuclease system of any one of claims 1-24 or claims 40-41, wherein said endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NO: 223-225.

43. The engineered nuclease system of any one of claims 1-24 or claims 40-42, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 28, SEQ ID NOs: 28-39, and SEQ ID NOs: 229-236.

44. The engineered nuclease system of any one of claims 1-24 or claims 40-43, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 144, SEQ ID NOs: 144-146, and SEQ ID NO: 135.

45. The engineered nuclease system of any one of claims 1-24 or claims 40-44, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 151 and SEQ ID NO: 156.

46. The engineered nuclease system of any one of claims 1-24 or claim 40-45, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 72; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 135 or SEQ ID NO: 144; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 151 or SEQ ID NO: 156.

47. The engineered nuclease system of any one of claims 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 84, SEQ ID NOs: 84-86, and SEQ ID NOs: 254-262.

48. The engineered nuclease system of any one of claims 1-24 or claim 47, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 128, SEQ ID NOs: 128-130, and SEQ ID NOs: 271- 279.

49. The engineered nuclease system of any one of claims 1-24 or claims 47-48, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 40, SEQ ID NOs: 40-42, and SEQ ID NOs: 237-245.

50. The engineered nuclease system of any one of claims 1-24 or claims 47-49, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 147, SEQ ID NO: 280, or SEQ ID NO: 136.

51. The engineered nuclease system of any one of claims 1-24 or claims 47-50, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 152 and SEQ ID NO: 157.

52. The engineered nuclease system of any one of claims 1-24 or claim 47-51, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 84; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 136 or SEQ ID NO: 147; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 152 or SEQ ID NO: 157.

53. The engineered nuclease system of any one of claims 1-24, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 87, or SEQ ID NOs: 87-88.

54. The engineered nuclease system of any one of claims 1-24 or claim 53, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 131 or SEQ ID NOs: 131-132.

55. The engineered nuclease system of any one of claims 1-24 or claims 53-54, wherein said endonuclease comprises at least 1, at least 2, at least 3, at least 4, or at least 5 peptide motifs selected from the group consisting of SEQ ID NO: 226-228.

56. The engineered nuclease system of any one of claims 1-24 or claims 53-55, wherein said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 43 or SEQ ID NOs: 43-44.

57. The engineered nuclease system of any one of claims 1-24 or claims 53-56, wherein said guide RNA structure comprises a tracr ribonucleic acid sequence comprising at least two hairpins comprising less than 5 base-paired ribonucleotides.

58. The engineered nuclease system of any one of claims 1-24 or claims 53-57, wherein said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to a sequence selected from the group consisting of SEQ ID NO: 148 or SEQ ID NO: 137.

59. The engineered nuclease system of any one of claims 1-24 or claims 53-58, wherein said endonuclease is configured to bind to a PAM comprising a sequence selected from the group consisting of SEQ ID NO: 153 and SEQ ID NO: 158.

60. The engineered nuclease system of any one of claims 1-24 or claim 53-59, wherein: a) said endonuclease comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 87; b) said guide RNA structure comprises a sequence at least 70%, 80%, or 90% identical to SEQ ID NO: 137 or SEQ ID NO: 148; and c) said endonuclease is configured to bind to a PAM comprising SEQ ID NO: 153 or SEQ ID NO: 158.

61. The engineered nuclease system of any one of claims 1-60, wherein said sequence identity is determined by a BLASTP, CLUSTALW, MUSCLE, MAFFT, or CLUSTALW having the parameters of the Smith-Waterman homology search algorithm.

62. The engineered nuclease system of claim 61, wherein said sequence identity is determined by said BLASTP homology search algorithm using parameters of a wordlength (W) of 3, an expectation (E) of 10, and a BLOSUM62 scoring matrix setting gap costs at existence of 11, extension of 1, and using a conditional compositional score matrix adjustment.

64. The engineered guide ribonucleic acid polynucleotide of claim 63, wherein said DNA-targeting segment is positioned 5' of both of said two complementary stretches of nucleotides.

65. The engineered guide ribonucleic acid polynucleotide of any of claims 63-64, wherein: a) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 138; b) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 139 or SEQ ID NOs: 139-143; c) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 144 or SEQ ID NOs: 144-146; d) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 147; or e) said protein binding segment comprises a sequence having at least 70%, at least 80%, or at least 90% identity to a sequence selected from the group consisting of SEQ ID NO: 148.

66. The engineered guide ribonucleic acid polynucleotide of any of claim 63-65, wherein: a) said guide ribonucleic acid polynucleotide comprises a tracr ribonucleic acid comprising a hairpin comprising at least 8, at least 10, or at least 12 base-paired ribonucleotides; or b) said guide ribonucleic acid polynucleotide comprises a tracr ribonucleic acid sequence comprising at least two hairpins comprising less than 5 base-paired ribonucleotides.

67. A deoxyribonucleic acid polynucleotide encoding the engineered guide ribonucleic acid polynucleotide of any one of claims 63-66.

69. A nucleic acid comprising an engineered nucleic acid sequence optimized for expression in an organism, wherein said nucleic acid encodes an endonuclease comprising a RuvC III domain having at least 70% sequence identity to any one of SEQ ID NOs: 45-88.

70. The nucleic acid of any one of claims 68-69, wherein said endonuclease comprises an HNH domain having at least 70% or at least 80% sequence identity to any one of SEQ ID NOs: 89-132.

71. The nucleic acid of any one of claims 68-70, wherein said endonuclease comprises a sequence according to any one of SEQ ID NOs: 170-179 or 292-293 or a variant thereof having at least 70% sequence identity thereto.

72. The nucleic acid of any one of claims 68-71, wherein said endonuclease comprises a sequence encoding one or more nuclear localization sequences (NLSs) proximal to an N- or C- terminus of said endonuclease.

73. The nucleic acid of claim 72, wherein said NLS comprises a sequence selected from SEQ ID NOs: 180-195.

74. The nucleic acid of any one of claims 68-73, wherein said organism is prokaryotic, bacterial, eukaryotic, fungal, plant, mammalian, rodent, or human.

75. The nucleic acid of claim 74, wherein said organism is E. coli, and wherein: a) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 170; b) said nucleic acid sequence has at least 70%, 80%, or 90% identity to a sequence selected from the group consisting of SEQ ID NOs: 171-172; c) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 173; d) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 174; or e) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 175.

76. The nucleic acid of claim 74, wherein said organism is human, and wherein: a) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO: 176; b) said nucleic acid sequence has at least 70%, 80%, or 90% identity to SEQ ID NO:

179.

78. A vector comprising the nucleic acid of any of claims 68-76.

79. The vector of any of claims 77-78, further comprising a nucleic acid encoding an engineered guide ribonucleic acid structure configured to form a complex with said endonuclease comprising: a) a guide ribonucleic acid sequence configured to hybridize to a target deoxyribonucleic acid sequence; and b) a tracr ribonucleic acid sequence configured to bind to said endonuclease.

80. The vector of any of claims 77-79, wherein the vector is a plasmid, a minicircle, a CELiD, an adeno-associated virus (AAV) derived virion, or a lentivirus.

81. A cell comprising the vector of any of claims 77-80.

82. A method of manufacturing an endonuclease, comprising cultivating said cell of claim 81.

83. A method for binding, cleaving, marking, or modifying a double-stranded deoxyribonucleic acid polynucleotide, comprising:

(a) contacting said double-stranded deoxyribonucleic acid polynucleotide with a class 2, type II Cas endonuclease in complex with an engineered guide ribonucleic acid structure configured to bind to said endonuclease and said double-stranded deoxyribonucleic acid polynucleotide;

(b) wherein said double-stranded deoxyribonucleic acid polynucleotide comprises a protospacer adjacent motif (PAM); and

(c) wherein said PAM comprises a sequence selected from the group consisting of any one of SEQ ID NOs: 149-153, SEQ ID NOs: 154-158, or SEQ ID NOs: 294-296.

84. A method of claim 83, wherein said double-stranded deoxyribonucleic acid polynucleotide comprises a first strand comprising a sequence complementary to a sequence of said engineered guide ribonucleic acid structure and a second strand comprising said PAM.

85. A method of claim 84, wherein said PAM is directly adjacent to the 3' end of said sequence complementary to said sequence of said engineered guide ribonucleic acid structure.

86. A method of any one of claims 82-85, wherein said class 2, type II Cas endonuclease is not a Cas9 endonuclease, a Casl4 endonuclease, a Casl2a endonuclease, a Casl2b endonuclease, a Cas 12c endonuclease, a Cas 12d endonuclease, a Casl2e endonuclease, a Casl3a endonuclease, a Cas 13b endonuclease, a Cas 13c endonuclease, or a Cas 13d endonuclease.

87. A method of any one of claims 82-86, wherein said class 2, type II Cas endonuclease is derived from an uncultivated microorganism.

88. A method of any one of claims 82-87, wherein said double-stranded deoxyribonucleic acid polynucleotide is a eukaryotic, plant, fungal, mammalian, rodent, or human double-stranded deoxyribonucleic acid polynucleotide.

89. A method of any one of claims 82-88, wherein: a) said PAM comprises SEQ ID NO: 149 or SEQ ID NO: 154; b) said PAM comprises SEQ ID NO: 150 or SEQ ID NO: 155; c) said PAM comprises SEQ ID NO: 151 or SEQ ID NO: 156; d) said PAM comprises SEQ ID NO: 152 or SEQ ID NO: 157; or e) said PAM comprises SEQ ID NO: 153 or SEQ ID NO: 158.

90. A method of modifying a target nucleic acid locus, said method comprising delivering to said target nucleic acid locus said engineered nuclease system of any one of claims 1-62, wherein said endonuclease is configured to form a complex with said engineered guide ribonucleic acid structure, and wherein said complex is configured such that upon binding of said complex to said target nucleic acid locus, said complex modifies said target nucleic acid locus.

91. A method of claim 89, wherein modifying said target nucleic acid locus comprises binding, nicking, cleaving, or marking said target nucleic acid locus.

92. A method of any of claims 89-91, wherein said target nucleic acid locus comprises deoxyribonucleic acid (DNA) or ribonucleic acid (RNA).

93. A method of claim 92, wherein said target nucleic acid comprises genomic DNA, viral DNA, viral RNA, or bacterial DNA.

94. A method of any one of claims 89-93, wherein said target nucleic acid locus is in vitro.

95. A method of any one of claims 89-93, wherein said target nucleic acid locus is within a cell.

96. A method of claim 95, wherein said cell is a prokaryotic cell, a bacterial cell, a eukaryotic cell, a fungal cell, a plant cell, an animal cell, a mammalian cell, a rodent cell, a primate cell, or a human cell.

97. A method of any one of claims 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering the nucleic acid of any of claims 68-73 or the vector of any of claims 77-79.

98. A method of any one of claims 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a nucleic acid comprising an open reading frame encoding said endonuclease.

99. A method of claim 97, wherein said nucleic acid comprises a promoter to which said open reading frame encoding said endonuclease is operably linked.

100. A method of any one of claims 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a capped mRNA containing said open reading frame encoding said endonuclease.

101. A method of any one of claims 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a translated polypeptide.

102. A method of any one of claims 95-96, wherein delivering said engineered nuclease system to said target nucleic acid locus comprises delivering a deoxyribonucleic acid (DNA) encoding said engineered guide ribonucleic acid structure operably linked to a ribonucleic acid (RNA) pol III promoter.

103. A method of any one of claims 89-102, wherein said endonuclease induces a single-stranded break or a double-stranded break at or proximal to said target locus.