Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
  • C12N15/09—Recombinant DNA-technology
  • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
  • C12N15/74—Vectors or expression systems specially adapted for prokaryotic hosts other than E. coli, e.g. Lactobacillus, Micromonospora
  • C12N15/78—Vectors or expression systems specially adapted for prokaryotic hosts other than E. coli, e.g. Lactobacillus, Micromonospora for Pseudomonas
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
  • C12N15/09—Recombinant DNA-technology
  • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
  • C12N15/67—General methods for enhancing the expression
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
  • C12N9/14—Hydrolases (3)
  • C12N9/78—Hydrolases (3) acting on carbon to nitrogen bonds other than peptide bonds (3.5)
  • C12N9/80—Hydrolases (3) acting on carbon to nitrogen bonds other than peptide bonds (3.5) acting on amide bonds in linear amides (3.5.1)
  • C12N9/82—Asparaginase (3.5.1.1)
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12Y—ENZYMES
  • C12Y305/00—Hydrolases acting on carbon-nitrogen bonds, other than peptide bonds (3.5)
  • C12Y305/01—Hydrolases acting on carbon-nitrogen bonds, other than peptide bonds (3.5) in linear amides (3.5.1)
  • C12Y305/01001—Asparaginase (3.5.1.1)
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N1/00—Microorganisms; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
  • C12N1/20—Bacteria; Culture media therefor
  • C12N1/205—Bacterial isolates
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12R—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES C12C - C12Q, RELATING TO MICROORGANISMS
  • C12R2001/00—Microorganisms ; Processes using microorganisms
  • C12R2001/01—Bacteria or Actinomycetales ; using bacteria or Actinomycetales
  • C12R2001/38—Pseudomonas
  • C12R2001/39—Pseudomonas fluorescens
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change

Definitions

• L-asparaginase catalyses the conversion of L-asparagine to L-aspartate.
• L-asparaginase type II from the bacterium E. coli is a tetrameric high-affinity periplasmic enzyme produced with a cleavable secretion signal sequence.
• L-asparagine amidohydrolase also known as L-asparagine amidohydrolase, it is the active ingredient in commercially approved drug products indicated for the treatment of patients having acute lymphoblastic leukemia (ALL).
• ALL acute lymphoblastic leukemia
• Elspar® approved in the United States for ALL treatment, has as its active ingredient E. coli L-asparaginase type II.
• Oncaspar® contains L-asparaginase (L- asparagine amidohydrolase) that is covalently conjugated to monomethoxypolyethylene glycol (mPEG).
• L-asparaginase L- asparagine amidohydrolase
• mPEG monomethoxypolyethylene glycol
• E. coli L-asparaginase type II is also used to treat other neoplastic conditions.
• the E. coli asparaginase can be purified from a culture of E. coli to yield the drug substance, e.g., genetically modified E. coli that is deficient in native asparaginase. In some cases, it is expressed from a gene fusion with a heterologous secretion signal peptide.
• Periplasmic localization of asparaginase can provide advantages in different expression systems including reduced production of inclusion bodies, reduced proteolysis and generation of an authentic protein N-terminus. Expression yields can be lower due to the limited availability of secretion pathway cofactors and/or the spatial restriction of the periplasmic space. Cytoplasmic expression of recombinant asaparaginase, can generate higher yields if the bacterial host cell cytoplasmic environment presents few penalties in regards to solubility, degradation and mis-folding of the asparaginase monomer.
• the method comprises: culturing a Pseudomonadales host cell in a culture medium and expressing the recombinant asparaginase in the periplasm of the Pseudomonadales host cell from an expression construct comprising a nucleic acid encoding the recombinant asparaginase; wherein the recombinant asparaginase is produced in the periplasm at a yield of about 31% to about 60% TCP soluble asparaginase.
• the soluble recombinant asparaginase is produced in the periplasm at a yield of about 10 g/L to about 38 g/L.
• the method further comprises measuring the activity of an amount of the recombinant type II asparaginase produced, using an activity assay.
• the nucleic acid encoding the recombinant asparaginase is optimized for expression in the host cell.
• the asparaginase is an Escherichia coli L-asparaginase type II.
• the nucleic acid encoding the recombinant asparaginase comprises a sequence at least 85% homologous to SEQ ID NO: 1 or 3.
• the recombinant asparaginase has an amino acid sequence at least 85% homologous to SEQ ID NO: 2.
• expression of the recombinant asparaginase is induced with addition of IPTG to the culture media.
• the IPTG is at a concentration in the culture media of about 0.14 mM to about 0.3 mM.
• expression of the recombinant asparaginase is induced when the Pseudomonad host cell has grown to a wet cell weight of about 0.05 g/g to about 0.4 g/g.
• the Pseudomonadales host cell is cultured at a pH of about 5.0 to about 8.0.
• the Pseudomonadales host cell is cultured at a temperature of about 22 °C to about 33 °C. In some embodiments, the Pseudomonadales host cell is cultured in a media comprising about 3g/L to about 8 g/L mannitol. In embodiments, the Pseudomonadales host cell is cultured in a media comprising no mannitol. In some embodiments, the Pseudomonadales host cell is cultured in a media comprising about 0.1 mM to about 1 mM CaCl 2 . In some embodiments, the Pseudomonadales host cell is a Pseudomonas fluorescens cell.
• the Pseudomonadales host cell is deficient in the expression of one or more asparaginases. In some embodiments, the Pseudomonadales host cell is deficient in the expression of one or more native asparaginases. In some embodiments, the deficiently expressed native asparaginase is a type I asparaginase. In some embodiments, the deficiently expressed native asparaginase is a type II asparaginase. In some embodiments, the Pseudomonadales host cell is deficient in the expression of one or more proteases. In some embodiments, the Pseudomonadales host cell overexpresses one or more folding modulators.
• the Pseudomonadales host cell is selected from at least one of: a host cell that overexpresses LepB; a host cell that overexpresses Tig; a host cell that overexpresses DsbA, DsbC, and Skp (DsbAC-Skp); a host cell that is deficient in Lon, HslUV, DegP l, DegP2, Pre, AprA, DegP2 S219A, Prc l, or AprA; a host cell that is deficient in AspGl ; a host cell that is deficient in AspG2; a host cell that does not overexpress a folding modulator, and is not deficient in a protease; a host cell that does not overexpress a folding modulator, is not deficient in a protease; and is not deficient in AspGl; a host cell that does not overexpress a folding modulator, is not deficient in a
• the Pseudomonadales host cell is selected from: a host cell that is deficient in Lon and HslUV; a host cell that is deficient in Lon, DegPl, DegP2, Pre, and AprA; a host cell that is deficient in Lon, DegPl, DegP2 S219A, Prcl, and AprA, and overexpresses DsbAC-Skp; a host cell that is deficient in AspGl and/or AspG2; a host cell that is deficient in AspGl and/or AspG2, and overexpresses Tig; a host cell that is deficient in AspGl and/or AspG2, and overexpresses LepB; a host cell that is deficient in AspGl and/or AspG2, and deficient in Lon and HslUV; a host cell that is deficient in AspGl and/or AspG2, and deficient in Lon, Deg
• the expression construct comprises a secretion leader.
• the secretion leader is selected from the group comprising the Pseudmonadales secretion leaders AnsB, 8484, IBP-S31A, pbp, 8584, LAO, Azu, PbpA20V, CupC2, and the Escherichia coli K-12 AnsB secretion leader.
• the secretion leader directs transfer of the recombinant asparaginase produced to the periplasm of the Pseudomonadales host cell.
• the method further comprises comparing the measured activity of the recombinant type II asparaginase produced with an activity measured in the same amount of a control type II asparaginase using the same activity assay.
• the control type II asparaginase comprises an E. coli type II asparaginase that has been commercially approved for use in patients.
• the recombinant type II asparaginase produced is selected for use in patients when it has about 80% to about 120% of the activity of the control type II asparaginase.
• the recombinant type II asparaginase produced is modified to increase half-life in patients.
• the recombinant type II asparaginase expressed from the expression construct is a recombinant E. coli type II asparaginase, wherein the nucleic acid encodes the recombinant E. coli type II asparaginase operably linked to the P. fluorescens AnsB secretion leader, and wherein the recombinant E. coli type II asparaginase is produced in the periplasm at a yield that is about 20% to about 100% greater than that of a recombinant P. fluorescens type II asparaginase produced in the periplasm by the same method, wherein the P.
• fluorescens type II asparaginase is expressed from a second expression construct comprising a nucleic acid encoding the recombinant P. fluorescens type II asparaginase operably linked to the P. fluorescens AnsB secretion leader.
• the second expression construct comprises a nucleic acid encoding the amino acid sequence set forth as SEQ ID NO: 55.
• FIG. 1 SDS-CGE Gel-like Images - Tier 1 Expression Plasmid Screen. Asparaginase small scale (0.5 ml) growth whole broth sonicate soluble (upper panel) and insoluble (lower panel) were analyzed by reduced SDS-CGE. The lane at the far left shows molecular weight marker ladder (upper panel MW ladder 119 kDa, 68 KDa, 48 kDa, 29 kDa, 21 kDa, 16 kDa; lower panel MW ladder 119 kDa, 68 KDa, 48 kDa, 29 kDa, 21 kDa, 16 kDa) and the lane at the far right shows the same ladders.
• molecular weight marker ladder upper panel MW ladder 119 kDa, 68 KDa, 48 kDa, 29 kDa, 21 kDa, 16 kDa
• FIG. 2 SDS-CGE Gel-like Images Shake Flask Expression Analysis. Asparaginase shake flask expression sonicate soluble (upper panel) and insoluble (lower panel) were analyzed by reduced SDS-CGE. The late at the far left shows molecular weight marker ladder (upper panel MW ladder 68 kDa, 48 kDa, 29 kDa, 21 kDa, 16 kDa; lower panel MW ladder 68 kDa, 58 kDa, 29 kDa, 21 kKa, 16 kDa), the 14 th lane and the far right lane show the same ladders.
• molecular weight marker ladder upper panel MW ladder 68 kDa, 48 kDa, 29 kDa, 21 kDa, 16 kDa
• FIG. 3 Mass Spectrometry Data - Shake Flask Expression Analysis.
• the left panel shows LC-MS data for STR55976, and the right panel shows data for STR55977.
• High levels of asparaginase production as a percentage of total cell protein are described herein, for example up to 60% TCP asparaginase, e.g., asparaginase monomer, with no detectable degradation, capable of forming active tetramer.
• High titers of asparaginase production are obtained using the methods of the invention, for example, up to 20 grams per liter of asparaginase, e.g., asparaginase monomer, with no detectable degradation, capable of forming active tetramer.
• Host cells for producing asparaginase include but are not limited to Pseudomonas, for example Pseudomonas fluorescens .
• the asparaginase expression construct can be codon-optimized according to the selected host strain.
• Nucleic acid constructs useful in the methods of the invention can encode an asparaginase gene operably linked to a nucleic acid sequence encoding a secretion signal (secretion leader), e.g., a periplasmic secretion leader native to P. fluorescens, resulting in expression of a secretion leader- asparaginase fusion protein.
• secretion leader e.g., a periplasmic secretion leader native to P. fluorescens
• the host cell has a mutation in one or more protease- encoding genes, resulting in the inactivation of the protease.
• a mutation resulting in inactivation of a protease or any other gene product can be any type of mutation known in the art to cause protein inactivation or prevent protein expression including but not limited to a substitution, insertion, or deletion mutation in either the coding sequence or a regulatory sequence of the gene .
• overexpression of a folding modulator can be achieved using any method known in the art, e.g., by plasmid expression or chromosomal integration of the folding modulator gene.
• the host cell has at least one protease inactivation and overexpresses at least one folding modulator.
• the secretion leader transports soluble asparaginase to the periplasm of the host cell.
• the asparaginase is retained in the cytoplasm.
• the asparaginase purification process does not require asparaginase solubilization and subsequent refolding.
• at least a portion of asparaginase is not expressed in inclusion bodies.
• recombinant asparaginase is expressed devoid of any peptide tag for purification and does not require additional processing upon purification.
• the secretion leader is efficiently processed from the solubly expressed
• an expression plasmid for periplasmic production of asparaginase does not utilize an antibiotic resistance marker gene for selection and maintenance, thus eliminating complicated processes for subsequent removal of plasmid DNA required for production of
• fermentation conditions are scalable for large-volume production.
• the methods provided herein yield high levels of soluble, active asparaginase.
• an amino acid sequence can be encoded by different nucleotide sequences due to the redundancy in the genetic code.
• the present invention thus includes the use of peptides or proteins that have the same amino acid sequences but are encoded by different nucleotide sequences.
• Type II L- asparaginases are used as part of a multi -agent chemotherapeutic regimen to treat ALL and other cancers. Certain cancer cells are unable to synthesize asparagine due to lack of asparagine synthetase, while normal cells can synthesize asparagine. Therefore, administration of the asparaginase to a patient results in hydrolysis of soluble asparagine and reduction in circulating asparagine. This can lead to death of the cancer cells with a lesser effect on normal cells. Asparaginases are described in, e.g., Pritsa and
• Elspar® (Biologic License Application 101063) is an E. coli L-asparaginase type II product, commercially approved in the United States for treatment of ALL in patients. Its active ingredient is E. coli L-asparaginase type II (see Elspar® package insert, incorporated herein by reference).
• the active ingredient in Oncaspar® (Biologic License Application 103411) is E. coli L-asparaginase type II covalently conjugated to monomethoxypolyethylene glycol (mPEG) (see Oncaspar® package insert, incorporated herein by reference). Oncaspar is approved in the United States for treatment of first line ALL, as well as ALL and hypersensitivity to native E. coli asparaginase.
• E. coli produces two asparaginases, L-asparaginase type I and L-asparaginase type II.
• L- asparaginase type I which has a low affinity for asparagine, is located in the cytoplasm.
• L-asparaginase type II is a tetrameric periplasmic enzyme with a high affinity for asparagine that is produced with a cleavable secretion leader sequence.
• U.S. Pat. Appl. No. US 2016/0060613 "Pegylated L-asparaginase" incorporated by reference in its entirety, describes common structural features of known L-asparaginases from bacterial sources.
• the E. coli A-l-3 L-asparaginase type II (amino acid sequence set forth in SEQ ID NO: 1 herein; SEQ ID NOS: 6-13 include secretion leader sequences) is produced using the methods of the invention.
• This asparaginase is described, e.g., in U.S. Pat. No. 7,807,436, "Recombinant host for producing L-asparaginase II," incorporated by reference herein in its entirety, wherein the sequence is set forth as SEQ ID NO: 1.
• L-asparaginase type II also is described by Nakamura, N., et al., 1972, "On the Productivity and Properties of L-Asparaginase from Escherichia coli A-l-3,"
• E. coli A-l- 3 is derived from the E. coli HAP strain, which produces high levels of asparaginse, described in Roberts, J., et al., 1968, "New Procedures for Purification of L-Asparaginase with High Yield from Escherichia coli " Journal of Bacteriology, 95:6, 2117-2123, incorporated by reference herein.
• an L-asparaginase type II protein produced using the methods of the invention is the E.coli K-12 L-asparaginase type II enzyme, which has an amino acid sequence encoded by the ansB gene described by Jennings et al., 1990, J. Bacterid. 172: 1491-1498 (GenBank No. M34277), both incorporated by reference herein (amino acid sequence set forth as SEQ ID NO: 3, including the native secretion leader sequence, and SEQ ID NO: 5, not including a secretion leader sequence).
• U.S. Pat. No. 7,807,436 reports that, relative to the L-asparaginase type II enzyme from Merck & Co., Inc. (Elspar®) and L-asparaginase type II enzyme from Kyowa Hakko Kogyo Co., Ltd., the E. coli K12 enzyme subunit has Val 2 7 in place of Ala 2 7, Asn 64 in place of Asp 64 , Ser 252 in place of Thr 252 and Thr 263 in place of Asn 263 .
• an L-asparaginase type II produced using the methods of the invention has an amino acid sequence set forth by Maita, T., et al, Dec. 1974, "Amino acid sequence of L-asparaginase from Escherichia coli," J. Biochem. 76(6): 1351-4, incorporated by reference herein.
• an L-asparaginase type II produced using the methods of the invention is a variant of the E. coli A-l-3 L-asparaginase type II or the E.coli K-12 L-asparaginase type II enzyme, wherein the variant has about 80% to about 120%, or greater, about 85% to about 120%, about 90% to about 120%, about 95% to about 120%, about 98% to about 120%, about 100% to about 120%, about 80% to about 100%, about 80% to about 90%, about 85% to about 1 15%, about 90% to about 1 10%, about 95% to about 155%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 98%, or at least about 100%, of the L-asparaginase type II activity of the E. coli A-l -3 L- asparaginase type II or the E. coli K-12 L-asparaginase type II enzyme.
• the E. coli L-asparaginase type II is encoded by a nucleic acid having a sequence wherein the codons are optimized for expression in the host cell as desired.
• a recombinant asparaginase produced using the methods of the invention is encoded by a nucleic acid sequence that is at least about 70% identical to a wild-type E. coli asparaginase gene.
• the recombinant asparaginase has an amino acid sequence that is at least about 70% identical to a wild type E. coli asparaginase.
• a recombinant asparaginase has a nucleic acid sequence that is at least about 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to a wild type E. coli asparaginase nucleic acid sequence.
• a recombinant asparaginase has an amino acid sequence that is at least about 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identical to a wild type E. coli asparaginase.
• Identity or “homology” expressed as a percentage herein describes a measure of similarity between two sequences. The extent of identity between two sequences, in some embodiments, is ascertained using a computer program and
• BLAST e.g., BLAST 2.0
• Altschul et al., J. Mol. Biol. 215 :403 ( 1990), publicly available through NCBI has exemplary search parameters as follows: Mismatch-2; gap open 5; gap extension 2.
• a BLASTP algorithm is typically used in combination with a scoring matrix, such as PAM100, PAM 250, BLOSUM 62 or BLOSUM 50.
• FASTA e.g., FASTA2 and FASTA3
• SSEARCH sequence comparison programs are also used to quantitate the extent of identity (Pearson et al., Proc. Natl. Acad. Sci. USA 85 :2444 (1988); Pearson, Methods Mol Biol. 132: 185 (2000); and Smith et al., J. Mol. Biol. 147: 195 (1981)).
• Recombinant type II asparaginase from E. coli is also known by the names Colaspase®, Elspar®, Kidrolase®, Leunase®, and Spectrila®.
• Pegaspargase® is the name for a pegylated version of E. coli asparaginase. Asparaginase is administered to patients with acute lymphoblastic leukemia, acute myeloid leukemia, and non-Hodgkin's lymphoma via intravenous, intramuscular, or subcutaneous injection.
• Asparaginase type II products commercially approved for patient use can be identified by accessing product information for asparaginase products available from respective countries' drug approval agencies.
• product information and approval records are publicly available in the United States for, e.g., Elspar (E. coli L-asparagine amidohydrolase, type EC-2; BLA # 101063) and Erwinaze® (asparaginase Erwinia chrysanthemi, BLA # 125359) from the U.S. Food and Drug
• modified versions of asparaginase are generated.
• modification includes substitutions, insertions, elongations, deletions, and derivatizations alone or in combination.
• modified versions of asparaginase have enhanced properties, such as increased half-life when administered to a patient.
• modified versions of asparaginase with increased half-life are pegylated.
• the peptides may include one or more modifications of a "non-essential" amino acid residue.
• a "non-essential" amino acid residue is a residue that can be altered, e.g., deleted, substituted, or derivatized, in the novel amino acid sequence without abolishing or substantially reducing the activity (e.g., the agonist activity) of the peptide (e.g., the analog peptide).
• the peptides may include one or more modifications of an "essential" amino acid residue.
• an "essential" amino acid residue is a residue that when altered, e.g., deleted, substituted, or derivatized, in the novel amino acid sequence the activity of the reference peptide is substantially reduced or abolished.
• the modified peptide may possess an activity of asparaginase of interest in the methods provided.
• the substitutions, insertions and deletions may be at the N-terminal or C-terminal end, or may be at internal portions of the protein.
• the protein may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more substitutions, both in a consecutive manner or spaced throughout the peptide molecule.
• the peptide may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more insertions, again either in consecutive manner or spaced throughout the peptide molecule.
• the peptide may also include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more deletions, again either in consecutive manner or spaced throughout the peptide molecule.
• the peptide, alone or in combination with the substitutions, insertions and/or deletions may also include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more amino acid additions.
• substitutions include conservative amino acid substitutions.
• a “conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain, or physicochemical characteristics (e.g., electrostatic, hydrogen bonding, isosteric, hydrophobic features).
• the amino acids may be naturally occurring or unnatural. Families of amino acid residues having similar side chains are known in the art. These families include amino acids with basic side chains (e.g.
• lysine, arginine, histidine acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, methionine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, tryptophan), ⁇ -branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Substitutions may also include non-conservative changes.
• Methods herein comprise expressing recombinant asparaginase from an expression construct in a Pseudomonas host cell.
• the expression construct in some cases, is a plasmid.
• a plasmid encoding asparaginase sequence comprises a selection marker, and host cells maintaining the plasmid are grown under selective conditions.
• the plasmid does not comprise a selection marker.
• the expression construct is integrated into the host cell genome.
• the expression construct encodes asparaginase fused to a secretion signal that directs asparaginase to the periplasm.
• the secretion signal is cleaved in the host cell.
• the expression construct encodes asparaginase without a secretion signal that directs the asparaginase to the cytoplasm.
• heterologous proteins including regulatory sequences (e.g., promoters, secretion leaders, and ribosome binding sites) useful in the methods of the invention in host strains, including Pseudomonas host strains, are described, e.g., in U.S. Patent No. 7, 618,799, "Bacterial leader sequences for increased expression,” in U.S. Pat. No. 7,985,564, "Expression systems with Sec- system secretion,” in U.S. Pat. Nos.
• regulatory sequences e.g., promoters, secretion leaders, and ribosome binding sites
• a secretion leader used in the context of the present invention is a secretion leader as disclosed in any of U.S. Pat. Nos. 7, 618,799, 7,985,564, 9,394,571, 9,580,719, 9,453,251, 8,603,824, and 8,530,171. These patents also describe bacterial host strains useful in practicing the methods herein, that have been engineered to overexpress folding modulators or wherein protease mutations have been introduced, in order to increase heterologous protein expression.
• an expression strain used in the methods of the invention is any expression strain described in Example 3, as listed in Table 11.
• an expression strain used in the methods of the invention is a microbial expression strain having a background phenotype of an expression strain described in Example 3, as listed in Table 11.
• an expression strain used in the methods of the invention is a microbial expression strain having a background phenotype of an expression strain described in Example 3, as listed in Table 11, and wherein the strain expresses the recombinant asparaginase in a fusion with the respective secretion leader as listed in Table 11.
• an expression strain used in the methods of the invention is a microbial expression strain having a background phenotype of expression strain STR57864, STR57865, STR57866, STR57860, STR57861, STR57862, STR57863 described in Example 3, as listed in Table 11, except that the expression strain is not a folding modulator overexpressor.
• an expression strain used in the methods of the invention is a microbial expression strain having a background phenotype of expression strain STR57864, STR57865, STR57866, STR57860, STR57861, STR57862, STR57863 described in Example 3, as listed in Table 11, cultured without mannitol. Promoters
• the promoters used in accordance with the methods herein may be constitutive promoters or regulated promoters.
• useful regulated promoters include those of the family derived from the lac promoter (i.e. the lacZ promoter), especially the tac and trc promoters described in U.S. Pat. No. 4,551,433 to DeBoer, as well as Ptacl6, Ptacl7, PtacII, PlacUV5, and the T71ac promoter.
• the promoter is not derived from the host cell organism.
• the promoter is derived from an E. coli organism.
• inducible promoter sequences are used to regulate expression of asparaginase in accordance with the methods herein.
• inducible promoters useful in the methods herein include those of the family derived from the lac promoter (i.e. the lacZ promoter), especially the tac and trc promoters described in U.S. Pat. No. 4,551,433 to DeBoer, as well as Ptacl6, Ptacl7, PtacII, PlacUV5, and the T71ac promoter.
• the promoter is not derived from the host cell organism.
• the promoter is derived from an E. coli organism.
• a lac promoter is used to regulate expression of asparaginase from a plasmid.
• an inducer is IPTG (isopropyl- -D-l-thiogalactopyranoside, also called “isopropylthiogalactoside").
• IPTG is added to culture to induce expression of asparaginase from a lac promoter in a Pseudomonas host cell.
• non-lac -type promoters useful in expression systems according to the methods herein include, e.g., those listed in Table 1.
• a promoter having the nucleotide sequence of a promoter native to the selected bacterial host cell also may be used to control expression of the transgene encoding the target polypeptide, e.g, a. Pseudomonas anthranilate or benzoate operon promoter (Pant, Pben).
• Tandem promoters may also be used in which more than one promoter is covalently attached to another, whether the same or different in sequence, e.g., a Pant-Pben tandem promoter (interpromoter hybrid) or a Plac- Plac tandem promoter, or whether derived from the same or different organisms.
• Regulated promoters utilize promoter regulatory proteins in order to control transcription of the gene of which the promoter is a part. Where a regulated promoter is used herein, a corresponding promoter regulatory protein will also be part of an expression system according to methods herein. Examples of promoter regulatory proteins include: activator proteins, e.g., E.
• coli catabolite activator protein MalT protein
• AraC family transcriptional activators repressor proteins, e.g., E. coli Lad proteins
• dual-function regulatory proteins e.g., E. coli NagC protein.
• Many regulated- promoter/promoter-regulatory-protein pairs are known in the art.
• the expression construct for the target protein(s) and the heterologous protein of interest are under the control of the same regulatory element.
• Promoter regulatory proteins interact with an effector compound, i.e., a compound that reversibly or irreversibly associates with the regulatory protein so as to enable the protein to either release or bind to at least one DNA transcription regulatory region of the gene that is under the control of the promoter, thereby permitting or blocking the action of a transcriptase enzyme in initiating transcription of the gene.
• Effector compounds are classified as either inducers or co-repressors, and these compounds include native effector compounds and gratuitous inducer compounds.
• Many regulated-promoter/promoter- regulatory-protein/effector-compound trios are known in the art.
• an effector compound is used throughout the cell culture or fermentation, in one embodiment in which a regulated promoter is used, after growth of a desired quantity or density of host cell biomass, an appropriate effector compound is added to the culture to directly or indirectly result in expression of the desired gene(s) encoding the protein or polypeptide of interest.
• a lad gene is sometimes present in the system.
• the lad gene which is normally a constitutively expressed gene, encodes the Lac repressor protein Lad protein, which binds to the lac operator of lac family promoters.
• the lad gene is sometimes also included and expressed in the expression system.
• Promoter systems useful in Pseudomonas are described in the literature, e.g., in U.S. Pat. App. Pub. No. 2008/0269070, also referenced above.
• soluble recombinant asparaginase is present in either the cytoplasm or periplasm of the cell during production.
• Secretion leaders useful for targeting proteins e.g.,
• expression constructs are provided that encode asparaginase fused to a secretion leader that transport asparaginase to the periplasm of a Pseudomonas cell.
• the secretion leader the secretion leader is cleaved from the asparaginase protein.
• the secretion leader facilitates production of soluble asparaginase.
• An expression construct useful in practicing the methods herein include, in addition to the protein coding sequence, the following regulatory elements operably linked thereto: a promoter, a ribosome binding site (RBS), a transcription terminator, and translational start and stop signals.
• the expression vector contains an optimal ribosome binding sequence.
• Modulating translation strength by altering the translation initiation region of a protein of interest can be used to improve the production of heterologous cytoplasmic proteins that accumulate mainly as inclusion bodies due to a translation rate that is too rapid. Secretion of heterologous proteins into the periplasmic space of bacterial cells can also be enhanced by optimizing rather than maximizing protein translation levels such that the translation rate is in sync with the protein secretion rate.
• the translation initiation region has been defined as the sequence extending immediately upstream of the ribosomal binding site (RBS) to approximately 20 nucleotides downstream of the initiation codon (McCarthy et al. (1990) Trends in Genetics 6:78-85, herein incorporated by reference in its entirety).
• RBS ribosomal binding site
• alternative RBS sequences can be utilized to optimize translation levels of heterologous proteins by providing translation rates that are decreased with respect to the translation levels using the canonical, or consensus, RBS sequence (AGGAGG; SEQ ID NO: 45) described by Shine and Dalgarno (Proc. Natl. Acad. Sci. USA 71 : 1342-1346, 1974).
• translation rate or “translation efficiency” is intended the rate of mRNA translation into proteins within cells.
• the Shine -Dalgarno sequence assists with the binding and positioning of the 30S ribosome component relative to the start codon on the mRNA through interaction with a pyrimidine-rich region of the 16S ribosomal RNA.
• the RBS also referred to herein as the Shine -Dalgarno sequence
• the RBS is located on the mRNA downstream from the start of transcription and upstream from the start of translation, typically from 4 to 14 nucleotides upstream of the start codon, and more typically from 8 to 10 nucleotides upstream of the start codon. Because of the role of the RBS sequence in translation, there is a direct relationship between the efficiency of translation and the efficiency (or strength) of the RBS sequence.
• modification of the RBS sequence results in a decrease in the translation rate of the heterologous protein.
• This decrease in translation rate may correspond to an increase in the level of properly processed protein or polypeptide per gram of protein produced, or per gram of host protein.
• the decreased translation rate can also correlate with an increased level of recoverable protein or polypeptide produced per gram of recombinant or per gram of host cell protein.
• the decreased translation rate can also correspond to any combination of an increased expression, increased activity, increased solubility, or increased translocation (e.g., to a periplasmic compartment or secreted into the extracellular space).
• the term “increased” is relative to the level of protein or polypeptide that is produced, properly processed, soluble, and/or recoverable when the protein or polypeptide of interest is expressed under the same conditions, or substantially the same conditions, and wherein the nucleotide sequence encoding the polypeptide comprises the canonical RBS sequence.
• the term “decreased” is relative to the translation rate of the protein or polypeptide of interest wherein the gene encoding the protein or polypeptide comprises the canonical RBS sequence.
• the translation rate can be decreased by at least about 5%, at least about 10%, at least about 15%, at least about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70, at least about 75% or more, or at least about 2-fold, about 3-fold, about 4- fold, about 5 -fold, about 6-fold, about 7-fold, or greater.
• the RBS sequence variants described herein can be classified as resulting in high, medium, or low translation efficiency.
• the sequences are ranked according to the level of translational activity compared to translational activity of the canonical RBS sequence.
• a high RBS sequence has about 60% to about 100% of the activity of the canonical sequence.
• a medium RBS sequence has about 40% to about 60% of the activity of the canonical sequence.
• a low RBS sequence has less than about 40% of the activity of the canonical sequence.
• RBS sequences are shown in Table 2. The sequences were screened for translational strength using COP-GFP as a reporter gene and ranked according to percentage of consensus RBS fluorescence. Each RBS variant was placed into one of three general fluorescence ranks: High ("Hi” - 100% Consensus RBS fluorescence), Medium (“Med” - 46-51% of Consensus RBS fluorescence), and Low (“Lo” - 16-29% Consensus RBS fluorescence).
• Useful RBSs are obtained from any of the species useful as host cells in expression systems according to, e.g., U.S. Pat. App. Pub. No. 2008/0269070 and U.S. Pat. App. Ser. No. 12/610,207. Many specific and a variety of consensus RBSs are known, e.g., those described in and referenced by D.
• Bacterial hosts including Pseudomonads, and closely related bacterial organisms are contemplated for use in practicing the methods herein.
• the Pseudomonad host cell is Pseudomonas fluorescens .
• the host cell is an E. coli cell.
• Host cells and constructs useful in practicing the methods herein are identified or made using reagents and methods known in the art and described in the literature, e.g., in U.S. Pat. App. Pub. No. 2009/0325230, "Protein Expression Systems,” incorporated herein by reference in its entirety.
• This publication describes production of a recombinant polypeptide by introduction of a nucleic acid construct into an auxotrophic Pseudomonas fluorescens host cell comprising a chromosomal lacl gene insert.
• the nucleic acid construct comprises a nucleotide sequence encoding the recombinant polypeptide operably linked to a promoter capable of directing expression of the nucleic acid in the host cell, and also comprises a nucleotide sequence encoding an auxotrophic selection marker.
• the auxotrophic selection marker is a polypeptide that restores prototrophy to the auxotrophic host cell.
• the cell is auxotrophic for proline, uracil, or combinations thereof.
• the host cell is derived from MB 101 (ATCC deposit PTA-7841). U. S. Pat. App. Pub. No.
• a pyrF- proC dual auxotrophic selection marker system in a P. fluorescens host cell is used.
• a pyrF deleted production host strain as described is often used as the background for introducing other desired genomic changes, including those described herein as useful in practicing the methods herein.
• a host cell useful in the methods of the present invention is deficient in the expression of at least one protease, overexpresses at least one folding modulator, or both.
• the host cell is not deficient in the expression of a protease and does not overexpress a folding modulator, and therefore is wild-type with respect to protease and folding modulator expression.
• the host cell is additionally deficient in a native L-asparaginase.
• the deficiency in the native L-asparaginase is generated by deleting or otherwise inactivating the native L-asparaginase gene using any suitable method known in the art.
• the host cell is deficient in a native Type I L-asparaginase, a native Type II L-asparaginase, or both.
• the host cell is wild-type with respect to protease and folding modulator expression, and deficient in a native Type I L-asparaginase and a Type II L-asparaginase.
• a host cell useful in the methods of the invention can be generated by one of skill in the art from MB 101, using known methods.
• the host cell is generated by deleting or otherwise inactivating the Type I L- asparaginase gene, the Type II L-asparaginase gene, or both, in MB 101.
• a production host strain useful in the methods of the present invention can be generated using a publicly available host cell, for example, P.
• fluorescens MB 101 e.g., by inactivating the pyrF gene, and/or the Type I L-asparaginase gene, and/or the Type II L-asparaginase gene, using any of many appropriate methods known in the art and described in the literature. It is also understood that a prototrophy restoring plasmid can be transformed into the strain, e.g., a plasmid carrying the pyrF gem from strain MB214 using any of many appropriate methods known in the art and described in the literature. Additionally, in such strains, proteases can be inactivated and folding modulator overexpression constructs introduced, using methods well known in the art.
• the host cell is of the order Pseudomonadales. Where the host cell is of the order Pseudomonadales, it may be a member of the family Pseudomonadaceae, including the genus Pseudomonas.
• Gamma Proteobacterial hosts include members of the species Escherichia coli and members of the species Pseudomonas fluorescens .
• Host cells of the order Pseudomonadales, of the family Pseudomonadaceae, or of the genus Pseudomonas are identifiable by one of skill in the art and are described in the literature (e.g., Bergey's Manual of Systematics of Archaea and Bacteria (online publication, 2015).
• Pseudomonas organisms may also be useful.
• Pseudomonads and closely related species include Gram -negative Proteobacteria Subgroup 1, which include the group of Proteobacteria belonging to the families and/or genera described in Bergey's Manual of Systematics of Archaea and Bacteria (online publication, 2015).
• Table 3 presents these families and genera of organisms.
• Pseudomonas and closely related bacteria are generally part of the group defined as "Gram(-) Proteobacteria Subgroup 1" or "Gram -Negative Aerobic Rods and Cocci” (Bergey's Manual of
• Gram -negative Proteobacteria Subgroup 1 also includes Proteobacteria that would be classified in this heading according to the criteria used in the classification.
• the heading also includes groups that were previously classified in this section but are no longer, such as the genera Acidovorax,
• Acidomonas which was created by regrouping organisms belonging to the genus Acetobacter as defined in Bergey's Manual of Systematics of Archaea and Bacteria (online publication, 2015).
• hosts include cells from the genus Pseudomonas, Pseudomonas enalia (ATCC 14393), Pseudomonas nigrifaciensi (ATCC 19375), and Pseudomonas putrefaciens (ATCC 8071), which have been reclassified respectively as Alteromonas haloplanktis, Alteromonas nigrifaciens , and Alter vmonas putrefaciens .
• Pseudomonas acidovorans (ATCC 15668) and Pseudomonas testosteroni (ATCC 11996) have since been reclassified as Comamonas acidovorans and Comamonas testosteroni, respectively; and Pseudomonas nigrifaciens (ATCC 19375) and Pseudomonas piscicida (ATCC 15057) have been reclassified respectively as Pseudoalteromonas nigrifaciens and Pseudoalteromonas piscicida.
• Gram- negative Proteobacteria Subgroup 1 also includes Proteobacteria classified as belonging to any of the families: Pseudomonadaceae, Azotobacteraceae (now often called by the synonym, the “Azotobacter group” of Pseudomonadaceae), Rhizobiaceae, and Methylomonadaceae (now often called by the synonym, “Methylococcaceae”).
• Proteobacterial genera falling within "Gram-negative Proteobacteria Subgroup 1" include: 1) Azotobacter group bacteria of the genus Azorhizophilus; 2) Pseudomonadaceae family bacteria of the genera Cellvibrio, Oligella, and Teredinibacter; 3) Rhizobiaceae family bacteria of the genera
• the host cell in some cases, is selected from "Gram -negative Proteobacteria Subgroup 16.”
• "Gram -negative Proteobacteria Subgroup 16" is defined as the group of Proteobacteria of the following Pseudomonas species (with the ATCC or other deposit numbers of exemplary strain(s) shown in parenthesis): Pseudomonas abietaniphila (ATCC 700689); Pseudomonas aeruginosa (ATCC 10145); Pseudomonas alcaligenes (ATCC 14909); Pseudomonas anguilliseptica (ATCC 33660); Pseudomonas citronellolis (ATCC 13674); Pseudomonas flavescens (ATCC 51555); Pseudomonas mendocina (ATCC 25411); Pseudomonas nitroreducens (ATCC
• Pseudomonas pseudoalcali genes ATCC 17 '440
• Pseudomonas resinovorans ATCC 14235
• Pseudomonas straminea (ATCC 33636); Pseudomonas agarici (ATCC 25941); Pseudomonas alcaliphila; Pseudomonas alginovora; Pseudomonas andersonii; Pseudomonas asplenii (ATCC 23835); Pseudomonas azelaica (ATCC 27162); Pseudomonas beyerinckii (ATCC 19372); Pseudomonas borealis; Pseudomonas boreopolis (ATCC 33662); Pseudomonas brassicacearum; Pseudomonas butanovora (ATCC 43655); Pseudomonas cellulosa (ATCC 55703); Pseudomonas aurantiaca (ATCC 33663); Pseudomonas chlororaphis (
• Pseudomonas fragi ATCC 4973
• Pseudomonas lundensis ATCC 49968
• Pseudomonas taetrolens ATCC 4683
• Pseudomonas cissicola ATCC 33616
• Pseudomonas coronafaciens Pseudomonas diterpeniphila
• Pseudomonas elongata ATCC 10144
• Pseudomonasflectens ATCC 12775
• Pseudomonas azotoformans Pseudomonas brenneri; Pseudomonas cedrella; Pseudomonas corrugata (ATCC 29736); Pseudomonas extremorientalis; Pseudomonas fluorescens (ATCC 35858); Pseudomonas gessardii; Pseudomonas libanensis; Pseudomonas mandelii (ATCC 700871); Pseudomonas marginalis (ATCC 10844); Pseudomonas migulae; Pseudomonas mucidolens (ATCC 4685); Pseudomonas orientalis; Pseudomonas rhodesiae; Pseudomonas synxantha (ATCC 9890); Pseudomonas tolaasii (ATCC
• Pseudomonas marginata (ATCC 25417); Pseudomonas mephitica (ATCC 33665); Pseudomonas denitrificans (ATCC 19244); Pseudomonas pertucinogena (ATCC 190); Pseudomonas pictorum (ATCC 23328); Pseudomonas psychrophila; Pseudomonas filva (ATCC 31418); Pseudomonas monteilii (ATCC 700476); Pseudomonas mosselii; Pseudomonas oryzihabitans (ATCC 43272); Pseudomonas plecoglossicida (ATCC 700383); Pseudomonas putida (ATCC 12633); Pseudomonas reactans;
• Pseudomonas spinosa (ATCC 14606); Pseudomonas balearica; Pseudomonas luteola (ATCC 43273);. Pseudomonas stutzeri (ATCC 17588); Pseudomonas amygdali (ATCC 33614); Pseudomonas avellanae (ATCC 700331); Pseudomonas caricapapayae (ATCC 33615); Pseudomonas cichorii (ATCC 10857); Pseudomonas ficuserectae (ATCC 35104); Pseudomonas fuscovaginae; Pseudomonas meliae (ATCC 33050); Pseudomonas syringae (ATCC 19310); Pseudomonas viridiflava (ATCC 13223); Pseudomonas thermocar
• the host cell in some cases, is selected from "Gram -negative Proteobacteria Subgroup 17."
• "Gram -negative Proteobacteria Subgroup 17" is defined as the group of Proteobacteria known in the art as the "fluorescent Pseudomonads" including those belonging, e.g., to the following Pseudomonas species: Pseudomonas azotoformans; Pseudomonas brenneri; Pseudomonas cedrella; Pseudomonas cedrina; Pseudomonas corrugata; Pseudomonas extremorientalis; Pseudomonas fluorescens;
• Pseudomonas synxantha Pseudomonas tolaasii; and Pseudomonas veronii.
• the methods provided herein comprise using a Pseudomonas host cell, comprising one or more mutations (e.g., a partial or complete deletion) in one or more protease genes, to produce recombinant asparaginase protein.
• a mutation in a protease gene facilitates generation of recombinant asparaginase protein.
• Exemplary target protease genes include those proteases classified as Aminopeptidases;
• Dipeptidases Dipeptidyl-peptidases and tripeptidyl peptidases; Peptidyl -dipeptidase s; Serine-type carboxypeptidases; Metallocarboxypeptidases; Cysteine-type carboxypeptidases; Omegapeptidases; Serine proteinases; Cysteine proteinases; Aspartic proteinases; Metallo proteinases; or Proteinases of unknown mechanism.
• Aminopeptidases include cytosol aminopeptidase (leucyl aminopeptidase), membrane alanyl aminopeptidase, cystinyl aminopeptidase, tripeptide aminopeptidase, prolyl aminopeptidase, arginyl aminopeptidase, glutamyl aminopeptidase, x-pro aminopeptidase, bacterial leucyl aminopeptidase, thermophilic aminopeptidase, clostridial aminopeptidase, cytosol alanyl aminopeptidase, lysyl aminopeptidase, x-trp aminopeptidase, tryptophanyl aminopeptidase, methionyl aminopeptidas, d- stereospecific aminopeptidase, aminopeptidase ey.
• cytosol aminopeptidase leucyl aminopeptidase
• membrane alanyl aminopeptidase cystinyl aminopeptidase
• Dipeptidases include x-his dipeptidase, x-arg dipeptidase, x-methyl-his dipeptidase, cys-gly dipeptidase, glu-glu dipeptidase, pro-x dipeptidase, x-pro dipeptidase, met-x dipeptidase, non-stereospecific dipeptidase, cytosol non-specific dipeptidase, membrane dipeptidase, beta-ala-his dipeptidase.
• Dipeptidyl-peptidases and tripeptidyl peptidases include dipeptidyl -peptidase i, dipeptidyl-peptidase ii, dipeptidyl peptidase iii, dipeptidyl-peptidase iv, dipeptidyl-dipeptidase, tripeptidyl-peptidase I, tripeptidyl -peptidase II.
• Peptidyl-dipeptidases include peptidyl-dipeptidase a and peptidyl-dipeptidase b.
• Serine-type carboxypeptidases include lysosomal pro- x carboxypeptidase, serine-type D-ala-D-ala carboxypeptidase, carboxypeptidase C, carboxypeptidase D.
• Metallocarboxypeptidases include carboxypeptidase a, carboxypeptidase B, lysine (arginine)
• carboxypeptidase gly-X carboxypeptidase, alanine carboxypeptidase, muramoylpentapeptide carboxypeptidase, carboxypeptidase h, glutamate carboxypeptidase, carboxypeptidase M,
• muramoyltetrapeptide carboxypeptidase zinc d-ala-d-ala carboxypeptidase, carboxypeptidase A2, membrane pro-x carboxypeptidase, tubulinyl-tyr carboxypeptidase, carboxypeptidase t.
• Omegapeptidases include acylaminoacyl-peptidase, peptidyl-glycinamidase, pyroglutamyl -peptidase I, beta-aspartyl- peptidase, pyroglutamyl -peptidase II, n-formylmethionyl -peptidase, pteroylpoly- [gamma] -glutamate carboxypeptidase, gamma-glu-X carboxypeptidase, acylmuramoyl-ala peptidase.
• Serine proteinases include chymotrypsin, chymotrypsin c, metridin, trypsin, thrombin, coagulation factor Xa, plasmin, enteropeptidase, acrosin, alpha-lytic protease, glutamyl, endopeptidase, cathepsin G, coagulation factor viia, coagulation factor ixa, cucumisi, prolyl oligopeptidase, coagulation factor xia, brachyurin, plasma kallikrein, tissue kallikrein, pancreatic elastase, leukocyte elastase, coagulation factor xiia, chymase, complement component clr55, complement component cls55, classical -complement pathway c3/c5 convertase, complement factor I, complement factor D, alternative -complement pathway c3/c5 convertase, cerevisin, hypodermin C, lysy
• Cysteine proteinases include cathepsin B, papain, ficin, chymopapain, asclepain, clostripain, streptopain, actinide, cathepsin 1, cathepsin H, calpain, cathepsin t, glycyl, endopeptidase, cancer procoagulant, cathepsin S, picomain 3C, picomain 2A, caricain, ananain, stem bromelain, fruit bromelain, legumain, histolysain, interleukin 1 -beta converting enzyme.
• Aspartic proteinases include pepsin A, pepsin B, gastricsin, chymosin, cathepsin D,
• neopenthesin renin, retropepsin, proopiomelanocortin converting enzyme, aspergillopepsin I, aspergillopepsin II, penicillopepsin, rhizopuspepsin, endothiapepsin, mucoropepsin, candidapepsin, saccharopepsin, rhodotorulapepsin, physaropepsin, acrocylindropepsin, polyporopepsin,
• Metallo proteinases include atrolysin a, microbial collagenase, leucolysin, interstitial collagenase, neprilysin, envelysin, iga-specific
• metalloendopeptidase procollagen N-endopeptidase, thimet oligopeptidase, neurolysin, stromelysin 1, meprin A, procollagen C-endopeptidase, peptidyl-lys metalloendopeptidase, astacin, stromelysin, 2, matrilysin gelatinase, aeromonolysin, pseudolysin, thermolysin, bacillolysin, aureolysin, coccolysin, mycolysin, beta-lytic metalloendopeptidase, peptidyl-asp metalloendopeptidase, neutrophil collagenase, gelatinase B, leishmanolysin, saccharolysin, autolysin, deuterolysin, serralysin, atrolysin B, atrolysin C, atroxase, atrolysin E, atroly
• proteases have both protease and chaperone-like activity. When these proteases are negatively affecting protein yield and/or quality it is often useful to specifically delete their protease activity, and they are overexpressed when their chaperone activity may positively affect protein yield and/or quality.
• proteases include, but are not limited to: Hspl00(Clp/Hsl) family members RXF04587.1 (clpA), RXF08347.1, RXF04654.2 (clpX), RXF04663.1, RXF01957.2 (hslU), RXF01961.2 (hslV); Peptidyl -prolyl cis-trans isomerase family member RXF05345.2 (ppiB); Metallopeptidase M20 family member RXF04892.1 (aminohydrolase); Metallopeptidase M24 family members RXF04693.1 (methionine aminopeptidase) and RXF03364.1 (methionine aminopeptidase); and Serine Peptidase S26 signal peptidase I family member RXFO 1181.1 (signal peptidase).
• a host strain useful for expressing an asparaginase e.g., an E. coli asparaginase type II
• a Pseudomonas host strain e.g., P. fluorescens, having a protease deficiency or inactivation (resulting from, e.g., a deletion, partial deletion, or knockout) and/or overexpressing a folding modulator, e.g., from a plasmid or the bacterial chromosome.
• the host strain is deficient in at least one protease selected from Lon, HslUV, DegPl, DegP2, Pre, AprA, DegP2 S219A, Prc l, and AprA.
• the host strain overexpresses a folding modulator selected from LepB, Tig, and DsbAC-Skp (i.e., the combination of DsbA, DsbC and Skp; Skp is OmpH RXF4702.1 , set forth as SEQ ID NO: 56 herein, with an example of a coding sequence set forth as SEQ ID NO: 57).
• folding modulators DsbA, DsbC and Skp (SEQ ID NOS: 25 and 26 of U.S. Pat. No. 9,394,571 and SEQ ID NO: 57 herein, respectively) can be expressed from an operon.
• the host strain is deficient in at least one protease selected from Lon, HslUV, DegP l, DegP2, Pre, AprA, DegP2 S219A, Prcl, and AprA, and overexpresses a folding modulator selected from LepB, Tig, and DsbAC-Skp.
• the host strain expresses the auxotrophic markers pyrF and proC, and has a protease deficiency and/or overexpresses a folding modulator. In embodiments, the host strain expresses any other suitable selection marker known in the art. In any of the above embodiments, an asparaginase, e.g., a native Type I and/or Type II asparaginase, is inactivated in the host strain.
• an asparaginase e.g., a native Type I and/or Type II asparaginase
• the host strain is a Pseudomonadales host cell is: deficient in Lon and HslUV; deficient in Lon, DegP l, DegP2, Pre, and AprA; deficient in Lon, DegP l, DegP2 S219A, Prc l, and AprA, and overexpresses DsbAC-Skp; deficient in AspGl and/or AspG2; deficient in AspGl and/or AspG2, and overexpresses Tig; deficient in AspGl and/or AspG2, and overexpresses LepB; deficient in AspGl and/or AspG2, and deficient in Lon and HslUV; a host cell that is deficient in AspGl and/or AspG2, and deficient in Lon, DegP l, DegP2, Pre, and AprA; or a host cell that is deficient in AspGl and/or AspG2, Lon
• folding modulators DsbA, DsbC and Skp (SEQ ID NOS: 56 and 57 herein) can be expressed from an operon.
• HslUV also referred to as HslVU
• HslU and V function and structure are described in the literature, e.g., by Bochtler et al., 1997, PNAS 94:6070-6074; Ramachandran et al., 2002, PNAS 99(1 1): 7396-7401 ; and Wang et al., 2001, Structure 9: 177-184, each incorporated herein by reference in its entirety.
• 9,580,719 (Table of SEQ ID NOS in columns 93-98 therein).
• U.S. Pat. No. 9,580,719 provides the sequence encoding HslU (RXF01957.2) and HslV (RXF01961.2) as SEQ ID NOS 18 and 19, respectively.
• the methods herein comprise expression of recombinant asparaginase from a construct that has been optimized for codon usage in a strain of interest.
• the strain is a Pseudomonas host cell, e.g., Pseudomonas fluorescens.
• Methods for optimizing codons to improve expression in bacterial hosts are known in the art and described in the literature. For example, optimization of codons for expression in a. Pseudomonas host strain is described, e.g., in U.S. Pat. App. Pub. No.2007/0292918, "Codon Optimization Method," incorporated herein by reference in its entirety.
• optimization steps may improve the ability of the host to produce the foreign protein.
• Protein expression is governed by a host of factors including those that affect transcription, mRNA processing, and stability and initiation of translation.
• the polynucleotide optimization steps may include steps to improve the ability of the host to produce the foreign protein as well as steps to assist the researcher in efficiently designing expression constructs.
• Optimization strategies may include, for example, the modification of translation initiation regions, alteration of mRNA structural elements, and the use of different codon biases.
• Methods for optimizing the nucleic acid sequence of to improve expression of a heterologous protein in a bacterial host are known in the art and described in the literature. For example, optimization of codons for expression in a. Pseudomonas host strain is described, e.g., in U.S. Pat. App. Pub. No.2007/0292918, "Codon Optimization Method,” incorporated herein by reference in its entirety.
• optimization addresses any of a number of sequence features of the heterologous gene.
• a rare codon-induced translational pause often results in reduced heterologous protein expression.
• a rare codon-induced translational pause includes the presence of codons in the
• polynucleotide of interest that are rarely used in the host organism may have a negative effect on protein translation due to their scarcity in the available tRNA pool.
• One method of improving optimal translation in the host organism includes performing codon optimization which sometimes results in rare host codons being removed from the synthetic polynucleotide sequence.
• Alternate translational initiation also sometimes results in reduced heterologous protein expression.
• Alternate translational initiation includes a synthetic polynucleotide sequence inadvertently containing motifs capable of functioning as a ribosome binding site (RBS). These sites, in some cases, result in initiating translation of a truncated protein from a gene-internal site.
• RBS ribosome binding site
• Repeat-induced polymerase slippage often results in reduced heterologous protein expression.
• Repeat-induced polymerase slippage involves nucleotide sequence repeats that have been shown to cause slippage or stuttering of DNA polymerase which sometimes results in frameshift mutations. Such repeats also often cause slippage of RNA polymerase.
• RNA polymerase In an organism with a high G+C content bias, there is sometimes a higher degree of repeats composed of G or C nucleotide repeats. Therefore, one method of reducing the possibility of inducing RNA polymerase slippage, includes altering extended repeats of G or C nucleotides.
• Interfering secondary structures also sometimes result in reduced heterologous protein expression. Secondary structures often sequester the RBS sequence or initiation codon and have been correlated to a reduction in protein expression. Stem loop structures are also often involved in transcriptional pausing and attenuation. An optimized polynucleotide sequence usually contains minimal secondary structures in the RBS and gene coding regions of the nucleotide sequence to allow for improved transcription and translation.
• Another feature that sometimes effect heterologous protein expression is the presence of restriction sites. By removing restriction sites that could interfere with subsequent sub-cloning of transcription units into host expression vectors a polynucleotide sequence is optimized.
• the optimization process often begins by identifying the desired amino acid sequence to be heterologously expressed by the host. From the amino acid sequence, a candidate polynucleotide or DNA is designed. During the design of the synthetic DNA sequence, the frequency of codon usage is often compared to the codon usage of the host expression organism and rare host codons are removed from the synthetic sequence. Additionally, the synthetic candidate DNA sequence is sometimes modified in order to remove undesirable enzyme restriction sites and add or remove any desired signal sequences, linkers or untranslated regions. The synthetic DNA sequence is often analyzed for the presence of secondary structure that may interfere with the translation process, such as G/C repeats and stem -loop structures. Before the candidate DNA sequence is synthesized, the optimized sequence design is often checked to verify that the sequence correctly encodes the desired amino acid sequence. Finally, the candidate DNA sequence is synthesized using DNA synthesis techniques, such as those known in the art.
• the general codon usage in a host organism such as P.
• fluorescens is often utilized to optimize the expression of the heterologous polynucleotide sequence.
• the percentage and distribution of codons that rarely would be considered as preferred for a particular amino acid in the host expression system is evaluated. Values of 5% and 10% usage is often used as cutoff values for the determination of rare codons.
• the codons listed in Table 4 have a calculated occurrence of less than 5% in the P. fluorescens MB214 genome and would be generally avoided in an optimized gene expressed in a P. fluorescens host. Table 4. Codons occurring at less than 5% in P. fluorescens MB214
• the present disclosure contemplates the use of any asparaginase coding sequence, including any sequence that has been optimized for expression in the Pseudomonas host cell being used. Sequences contemplated for use are often optimized to any degree as desired, including, but not limited to, optimization to eliminate: codons occurring at less than 5% in the Pseudomonas host cell, codons occurring at less than 10% in the Pseudomonas host cell, a rare codon-induced translational pause, a putative internal RBS sequence, an extended repeat of G or C nucleotides, an interfering secondary structure, a restriction site, or combinations thereof.
• amino acid sequence of any secretion leader useful in practicing the methods provided herein is encoded by any appropriate nucleic acid sequence. Codon optimization for expression in E. coli is described, e.g., by Welch, et al., 2009, PLoS One, "Design Parameters to Control Synthetic Gene Expression in Escherichia coli," 4(9): e7002, Ghane, et al., 2008, Krishna R. et al., (2008) Mol Biotechnology "Optimization of the AT-content of Codons Immediately Downstream of the Initiation Codon and Evaluation of Culture Conditions for High-level Expression of Recombinant Human G-CSF in Escherichia coli " 38:221-232.
• a high throughput screen is often conducted to determine optimal conditions for expressing soluble recombinant asparaginase.
• the conditions that be varied in the screen include, for example, the host cell, genetic background of the host cell (e.g., deletions of different proteases), type of promoter in an expression construct, type of secretion leader fused to encoded asparaginase, temperature of growth, OD of induction when an inducible promoter is used, amount of inducer added (e.g.
• IPTG IPTG used for induction when a lacZ promoter or derivative thereof is used
• duration of protein induction temperature of growth following addition of an inducing agent to a culture
• rate of agitation of culture rate of agitation of culture
• method of selection for plasmid maintenance volume of culture in a vessel
• method of cell lysing amount of IPTG used for induction when a lacZ promoter or derivative thereof is used
• a library (or “array") of host strains is provided, wherein each strain (or “population of host cells") in the library has been genetically modified to modulate the expression of one or more target genes in the host cell.
• An “optimal host strain” or “optimal expression system” is often identified or selected based on the quantity, quality, and/or location of the expressed protein of interest compared to other populations of phenotypically distinct host cells in the array.
• an optimal host strain is the strain that produces the polypeptide of interest according to a desired specification. While the desired specification will vary depending on the polypeptide being produced, the specification includes the quality and/or quantity of protein, whether the protein is sequestered or secreted, protein folding, and the like.
• the optimal host strain or optimal expression system produces a yield, characterized by the amount of soluble heterologous protein, the amount of recoverable heterologous protein, the amount of properly processed heterologous protein, the amount of properly folded heterologous protein, the amount of active heterologous protein, and/or the total amount of heterologous protein, of a certain absolute level or a certain level relative to that produced by an indicator strain, i.e., a strain used for comparison.
• Growth conditions useful in the methods herein often comprise a temperature of about 4°C to about 42°C and a pH of about 5.7 to about 8.8.
• expression is often induced by adding IPTG to a culture at a final
• the pH of the culture is sometimes maintained using pH buffers and methods known to those of skill in the art. Control of pH during culturing also is often achieved using aqueous ammonia. In embodiments, the pH of the culture is about 5.7 to about 8.8.
• the pH is about 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, or 8.8
• the pH is about 5.7 to 5.9, 5.8 to 6.0, 5.9 to 6.1, 6.0 to 6.2, 6.1 to 6.3, 6.2 to 6.5, 6.4 to 6.7, 6.5 to 6.8, 6.6 to 6.9, 6.7 to 7.0, 6.8 to 7.1, 6.9 to 7.2, 7.0 to 7.3, 7.1 to 7.4, 7.2 to 7.5, 7.3 to 7.6, 7.4 to 7.7, 7.5 to 7.8, 7.6 to 7.9, 7.7 to 8.0, 7.8 to 8.1, 7.9 to 8.2, 8.0 to 8.3, 8.1 to 8.4, 8.2 to 8.5, 8.3 to 8.6, 8.4
• the growth temperature is maintained at about 4 °C to about 42 °C.
• the growth temperature is about 4 °C, about 5 °C, about 6 °C, about 7 °C, about 8 °C, about 9 °C, about 10 °C, about 1 1 °C, about 12 °C, about 13 °C, about 14 °C, about 15 °C, about 16 °C, about 17 °C, about 18 °C, about 19 °C, about 20 °C, about 21 °C, about 22 °C, about 23 °C, about 24 °C, about 25 °C, about 26 °C, about 27 °C, about 28 °C, about 29 °C, about 30 °C, about 31 °C, about 32 °C, about 33 °C, about 34 °C, about 35 °C, about 36 °C, about 37 °C, about 38 °C, about 39 °C, about 40
• the growth temperature is maintained at about 25 °C to about 27 °C, about 25 °C to about 28 °C, about 25 °C to about 29 °C, about 25 °C to about 30 °C, about 25 °C to about 31 °C, about 25 °C to about 32 °C, about 25 °C to about 33 °C, about 26 °C to about 28 °C, about 26 °C to about 29 °C, about 26 °C to about 30 °C, about 26 °C to about 31 °C, about 26 °C to about 32 °C, about 27 °C to about 29 °C, about 27 °C to about 30 °C, about 27 °C to about 31 °C, about 27 °C to about 32 °C, about 26 °C to about 33 °C, about 28 °C to about 30 °C, about 28 °C to about 31 °C, about 27 °C to about 32 °C, about 26 °C to about 33
• the temperature is changed during culturing.
• the temperature is maintained at about 30 °C to about 32 °C before an agent to induce expression from the construct encoding the polypeptide or protein of interest is added to the culture, and the temperature is dropped to about 25 °C to about 27 °C after adding an agent to induce expression, e.g., IPTG is added to the culture.
• the temperature is maintained at about 30 °C before an agent to induce expression from the construct encoding the polypeptide or protein of interest is added to the culture, and the temperature is dropped to about 25 °C after adding an agent to induce expression is added to the culture. Induction
• inducible promoters are often used in the expression construct to control expression of the recombinant asparaginase, e.g., a lac promoter.
• the effector compound is an inducer, such as a gratuitous inducer like IPTG (isopropyl- -D-l -thiogalactopyranoside, also called
• a lac promoter derivative is used, and asparaginase expression is induced by the addition of IPTG to a final concentration of about 0.01 mM to about 1.0 mM, when the cell density has reached a level identified by an OD575 of about 25 to about 160.
• the OD575 at the time of culture induction for asparaginase is about 25, about 50, about 55, about 60, about 65, about 70, about 80, about 90, about 100, about 1 10, about 120, about 130, about 140, about 150, about 160, about 170 about 180.
• the OD575 is about 80 to about 100, about 100 to about 120, about 120 to about 140, about 140 to about 160. In other embodiments, the OD575 is about 80 to about 120, about 100 to about 140, or about 120 to about 160. In other embodiments, the OD575 is about 80 to about 140, or about 100 to 160.
• the cell density is often measured by other methods and expressed in other units, e.g., in cells per unit volume. For example, an OD575 of about 25 to about 160 of a Pseudomonas fluorescens culture is equivalent to approximately 4 x 10 10 to about 1.6 x 10 11 colony forming units per mL or 1 1 to 70 g/L dry cell weight.
• asparaginase expression is induced by the addition of IPTG to a final concentration of about 0.01 mM to about 1.0 mM, when the cell density has reached a wet cell weight of about 0.05 g/g to about 0.4 g/g.
• the wet cell weight is about 0.05 g/g, about 0.1 g/g, about 0.15 g/g, about 0.2 g/g, about 0.25 g/g, about 0.30 g/g, about 0.35 g/g, about 0.40 g/g, about 0.05 g/g to about 0.1 g/g, about 0.05 g/g to about 0.15 g/g, about 0.05 g/g to about 0.20 g/g, about 0.05 g/g to about 0.25 g/g, about 0.05 g/g to about 0.30 g/g, about 0.05 g/g to about 0.35 g/g, about 0.1 g/g to about 0.40 g/g, about 0.15 g/g to about 0.40 g/g, about 0.20 g/g to about 0.40 g/g, about 0.25 g/g to about 0.40 g/g, about 0.30 g/g to about 0.35 g/g, about 0.1 g/g to
• the cell density at the time of culture induction is equivalent to the cell density as specified herein by the absorbance at OD575, regardless of the method used for determining cell density or the units of measurement.
• One of skill in the art will know how to make the appropriate conversion for any cell culture.
• the final IPTG concentration of the culture is about 0.01 mM, about 0.02 mM, about 0.03 mM, about 0.04 mM, about 0.05 mM, about 0.06 mM, about 0.07 mM, about 0.08 mM, about 0.09 mM, about 0.1 mM, about 0.2 mM, about 0.3 mM, about 0.4 mM, about 0.5 mM, about 0.6 mM, about 0.7 mM, about 0.8 mM, about 0.9 mM, or about 1 mM.
• the final IPTG concentration of the culture is about 0.08 mM to about 0.1 mM, about .1 mM to about 0.2 mM, about .2 mM to about 0.3 mM, about .3 mM to about 0.4 mM, about .2 mM to about 0.4 mM, about 0.08 to about 0.2mM, or about 0.1 to 1 mM.
• the promoter is a constitutive promoter.
• cultures are often grown for a period of time, for example about 24 hours, during which time the recombinant asparaginase is expressed.
• a culture is often grown for about 1 hr, about 2 hr, about 3 hr, about 4 hr, about 5 hr, about 6 hr, about 7 hr, about 8 hr, about 9 hr, about 10 hr, about 11 hr, about 12 hr, about 13 hr, about 14 hr, about 15 hr, about 16 hr, about 17 hr, about 18 hr, about 19 hr, about 20 hr, about 21 hr, about 22 hr, about 23 hr, about 24 hr, about 36 hr, or about 48 hr.
• the culture After an inducing agent is added to a culture, the culture is grown for about 1 to 48 hrs, about 1 to 24 hrs, about 10 to 24 hrs, about 15 to 24 hrs, or about 20 to 24 hrs. Cell cultures are often concentrated by centrifugation, and the culture pellet resuspended in a buffer or solution appropriate for the subsequent lysis procedure.
• cells are disrupted using equipment for high pressure mechanical cell disruption (which are available commercially, e.g., Microfluidics Microfluidizer, Constant Cell Disruptor, Niro- Soavi homogenizer or APV-Gaulin homogenizer).
• Cells expressing asparaginase are often disrupted, for example, using sonication. Any appropriate method known in the art for lysing cells are often used to release the soluble fraction.
• chemical and/or enzymatic cell lysis reagents such as cell-wall lytic enzyme and EDTA, are often used.
• Use of frozen or previously stored cultures is also contemplated in the methods herein. Cultures are sometimes OD-normalized prior to lysis. For example, cells are often normalized to an OD600 of about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, or about 20.
• Centrifugation is performed using any appropriate equipment and method. Centrifugation of cell culture or lysate for the purposes of separating a soluble fraction from an insoluble fraction is well- known in the art. For example, lysed cells are sometimes centrifuged at 20,800 ⁇ g for 20 minutes (at 4° C), and the supernatants removed using manual or automated liquid handling. The pellet (insoluble) fraction is resuspended in a buffered solution, e.g., phosphate buffered saline (PBS), pH 7.4.
• PBS phosphate buffered saline
• Resuspension is often carried out using, e.g., equipment such as impellers connected to an overhead mixer, magnetic stir-bars, rocking shakers, etc.
• fermentation is used in the methods of producing recombinant asparaginase.
• the expression system according to the present disclosure is cultured in any fermentation format. For example, batch, fed-batch, semi -continuous, and continuous fermentation modes may be employed herein.
• the fermentation medium may be selected from among rich media, minimal media, and mineral salts media. In other embodiments either a minimal medium or a mineral salts medium is selected. In certain embodiments, a mineral salts medium is selected.
• Mineral salts media consists of mineral salts and a carbon source such as, e.g., glucose, sucrose, or glycerol.
• mineral salts media include, e.g., M9 medium, P seudomonas medium (ATCC 179), and Davis and Mingioli medium (see, B D Davis & E S Mingioli (1950) J. Bact. 60: 17-28).
• the mineral salts used to make mineral salts media include those selected from among, e.g., potassium phosphates, ammonium sulfate or chloride, magnesium sulfate or chloride, and trace minerals such as calcium chloride, borate, and sulfates of iron, copper, manganese, and zinc.
• no organic nitrogen source such as peptone, tryptone, amino acids, or a yeast extract
• an inorganic nitrogen source is used and this may be selected from among, e.g., ammonium salts, aqueous ammonia, and gaseous ammonia.
• a mineral salts medium will typically contain glucose or glycerol as the carbon source.
• minimal media often contains mineral salts and a carbon source, but is often supplemented with, e.g., low levels of amino acids, vitamins, peptones, or other ingredients, though these are added at very minimal levels.
• Media is often prepared using the methods described in the art, e.g., in U.S. Pat. App. Pub. No.
• Fermentation may be performed at any scale.
• the expression systems according to the present disclosure are useful for recombinant protein expression at any scale.
• microliter-scale, milliliter scale, centiliter scale, and deciliter scale fermentation volumes may be used, and 1 Liter scale and larger fermentation volumes are often used.
• the fermentation volume is at or above about 1 Liter. In embodiments, the fermentation volume is about 0.5 liters to about 100 liters. In embodiments, the fermentation volume is about 1 liter, about 2 liters, about 3 liters, about 4 liters, about 5 liters, about 6 liters, about 7 liters, about 8 liters, about 9 liters, or about 10 liters.
• the fermentation volume is about 0.5 liters to about 2 liters, about 0.5 liters to about 5 liters, about 0.5 liters to about 10 liters, about 0.5 liters to about 25 liters, about 0.5 liters to about 50 liters, about 0.5 liters to about 75 liters, about 10 liters to about 25 liters, about 25 liters to about 50 liters, or about 50 liters to about 100 liters
• the fermentation volume is at or above 5 Liters, 10 Liters, 15 Liters, 20 Liters, 25 Liters, 50 Liters, 75 Liters, 100 Liters, 200 Liters, 500 Liters, 1,000 Liters, 2,000 Liters, 5,000 Liters, 10,000 Liters, or 50,000 Liters. Protein Analysis
• recombinant asparaginase protein produced by the methods of the provided herein is analyzed.
• Recombinant asparaginase is sometimes analyzed, for example, by biolayer interferometry, SDS-PAGE, Western blot, Far Western blot, ELISA, absorbance, or mass spectrometry (e.g., tandem mass spectrometry).
• the concentration and/or amounts of recombinant asparaginase protein generated are determined, for example, by Bradford assay, absorbance, Coomassie staining, mass spectrometry, etc.
• Protein yield in the insoluble and soluble fractions as described herein are often determined by methods known to those of skill in the art, for example, by capillary gel electrophoresis (CGE), and Western blot analysis. Soluble fractions are often evaluated, for example, using biolayer interferometry.
• CGE capillary gel electrophoresis
• Soluble fractions are often evaluated, for example, using biolayer interferometry.
• the asparaginase monomer is capable of forming active tetramer, e.g., in cell lysate, cell sonicate, andjipon further purification.
• the recombinant asparaginase in a bacterial expression system, e.g., in a E. coli or Pseudomonas host strain, the recombinant protein can be purified using any suitable method known in the art, e.g., to remove host cell proteins. Purification methods can include, e.g., cation exchange chromatography, anion exchange chromatography, size exclusion chromatography, high performance liquid chromatography (HPLC), or a combination of these and/or other known methods.
• HPLC high performance liquid chromatography
• a measurable characteristic e.g., activity, size, length, or other characteristic indicative of active and/or intact protein
• an asparaginase standard sample e.g., a commercially obtained asparaginase.
• the amount of asparaginase protein in a sample can be determined by any suitable assay known in the art for protein measurement, and the activity by any suitable assay, e.g., as described herein.
• Useful measures of protein yield include, e.g., the amount of recombinant protein per culture volume (e.g., grams or milligrams of protein/liter of culture), percent or fraction of recombinant protein measured in the insoluble pellet obtained after lysis (e.g., amount of recombinant protein in extract supernatant/amount of protein in insoluble fraction), percent or fraction of active protein (e.g., amount of active protein/amount protein used in the assay), percent or fraction of total cell protein (tcp), amount of protein/cell, and percent dry biomass.
• the amount of recombinant protein per culture volume e.g., grams or milligrams of protein/liter of culture
• percent or fraction of recombinant protein measured in the insoluble pellet obtained after lysis e.g., amount of recombinant protein in extract supernatant/amount of protein in insoluble fraction
• percent or fraction of active protein e.g., amount of active protein/amount protein used in the assay
• the methods herein are used to obtain a yield of soluble recombinant asparaginase protein, e.g., a monomelic or tetrameric type II asparaginase, of about 20% to about 90% total cell protein.
• soluble recombinant asparaginase protein e.g., a monomelic or tetrameric type II asparaginase
• the yield of soluble recombinant asparaginase is about 20% total cell protein, about 25% total cell protein, about 30% total cell protein, about 31% total cell protein, about 32% total cell protein, about 33% total cell protein, about 34% total cell protein, about 35% total cell protein, about 36% total cell protein, about 37% total cell protein, about 38% total cell protein, about 39% total cell protein, about 40% total cell protein, about 41% total cell protein, about 42% total cell protein, about 43% total cell protein, about 44% total cell protein, about 45% total cell protein, about 46% total cell protein, about 47% total cell protein, about 48% total cell protein, about 49% total cell protein, about 50% total cell protein, about 51% total cell protein, about 52% total cell protein, about 53% total cell protein, about 54% total cell protein, about 55% total cell protein, about 56% total cell protein, about 57% total cell protein, about 58% total cell protein, about 59% total cell protein, about 60% total cell protein, about 65% total cell protein, about 70%
• the yield of soluble recombinant asparaginase is about 20% to about 25% total cell protein, about 20% to about 30% total cell protein, about 20% to about 35% total cell protein, about 20% to about 40% total cell protein, about 20% to about 45% total cell protein, about 20% to about 50% total cell protein, about 20% to about 55% total cell protein, about 20% to about 60% total cell protein, about 20% to about 65% total cell protein, about 20% to about 70% total cell protein, about 20% to about 75% total cell protein, about 20% to about 80% total cell protein, about 20% to about 85% total cell protein, about 20% to about 90% total cell protein, about 25% to about 90% total cell protein, about 30% to about 90% total cell protein, about 35% to about 90% total cell protein, about 40% to about 90% total cell protein, about 45% to about 90% total cell protein, about 50% to about 90% total cell protein, about 55% to about 90% total cell protein, about 60% to about 90% total cell protein, about 65% to about 90% total cell protein, about 70% to about 90% total cell protein, about 75% to about 90% total cell protein, about
• the methods herein are used to obtain a yield of soluble recombinant asparaginase protein, e.g., a monomelic or tetrameric type II asparaginase, of about 1 gram per liter to about 50 grams per liter.
• soluble recombinant asparaginase protein e.g., a monomelic or tetrameric type II asparaginase
• the yield of soluble recombinant asparaginase is about 1 grams per liter, about 2 grams per liter, about 3 grams per liter, about 4 grams per liter, about 5 grams per liter, about 6 grams per liter, about 7 grams per liter, about 8 grams per liter, about 9 grams per liter, about 10 gram per liter, about 11 grams per liter, about 12 grams per liter, about 13 grams per liter, about 14 grams per liter, about 15 grams per liter, about 16 grams per liter, about 17 grams per liter, about 18 grams per liter, about 19 grams per liter, about 20 grams per liter, about 21 grams per liter, about 22 grams per liter, about 23 grams per liter about 24 grams per liter, about 25 grams per liter, about 26 grams per liter, about 27 grams per liter, about 28 grams per liter, about 30 grams per liter, about 35 grams per liter, about 40 grams per liter, about 45 grams per liter, about 50 grams per liter, about 1 grams
• the soluble recombinant protein yield is about 10 gram per liter to about 13 grams per liter, about 12 grams per liter to about 14 grams per liter, about 13 grams per liter to about 15 grams per liter, about 14 grams per liter to about 16 grams per liter, about 15 grams per liter to about 17 grams per liter, about 16 grams per liter to about 18 grams per liter, about 17 grams per liter to about 19 grams per liter, about 18 grams per liter to about 20 grams per liter, about 20 grams per liter to about 22 grams per liter, about 22 grams per liter to about 24 grams per liter, or about 23 grams per liter to about 25 grams per liter.
• the soluble recombinant protein yield is about 10 grams per liter to about 25 grams per liter, about 12 gram per liter to about 24 grams per liter, about 14 grams per liter to about 22 grams per liter, about 16 grams per liter to about 20 grams per liter, or about 18 grams per liter to about 20 grams per liter.
• the extracted protein yield is about 5 grams per liter to about 15 grams per liter, about 5 gram per liter to about 25 grams per liter, about 10 grams per liter to about 15 grams per liter, about 10 grams per liter to about 25 grams per liter, about 15 grams per liter to about 20 grams per liter, about 15 grams per liter to about 25 grams per liter, or about 18 grams per liter to about 25 grams per liter.
• the amount of recombinant asparaginase, e.g., a monomelic or tetrameric type II asparaginase, detected in the soluble fraction is about 10% to about 100% of the amount of the total recombinant asparaginase produced. In embodiments, this amount is about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95% or about 99%, or about 100% of the amount of the total recombinant asparaginase produced.
• this amount is about 10% to about 20%, 20% to about 50%, about 25% to about 50%, about 25% to about 50%, about 25% to about 95%, about 30% to about 50%, about 30% to about 40%, about 30% to about 60%, about 30% to about 70%, about 35% to about 50%, about 35% to about 70%, about 35% to about 75%, about 35% to about 95%, about 40% to about 50%, about 40% to about 95%, about 50% to about 75%, about 50% to about 95%, about 70% to about 95%, or about 80 to about 100% of the amount of the total recombinant asparaginase produced.
• the amount of soluble recombinant asparaginase is expressed as a percentage of the total soluble protein produced in a culture.
• Data expressed in terms of recombinant asparaginase protein weight/volume of cell culture at a given cell density can be converted to data expressed as percent recombinant protein of total cell protein. It is within the capabilities of a skilled artisan to convert volumetric protein yield to % total cell protein, for example, knowing the amount of total cell protein per volume of cell culture at the given cell density.
• This number can be determined if one knows 1) the cell weight/volume of culture at the given cell density, and 2) the percent of cell weight comprised by total protein. For example, at an OD550 of 1.0, the dry cell weight of E. coli is reported to be 0.5 grams/liter ("Production of Heterologous Proteins from Recombinant DNA Escherichia coli in Bench Fermentors," Lin, N.S., and Swartz, J.R., 1992,
• a bacterial cell is comprised of polysaccharides, lipids, and nucleic acids, as well as proteins.
• An E. coli cell is reported to be about 52.4 to 55% protein by references including, but not limited to, Da Silva, N.A., et al., 1986, "Theoretical Growth Yield Estimates for Recombinant Cells," Biotechnology and Bioengineering, Vol. XXVIII: 741- 746 , estimating protein to make up 52.4% by weight of E. coli cells, and "Escherichia coli and
• an A600 of 1.0 for E. coli resulted in a wet cell weight of 1.7 grams/liter and a dry cell weight of 0.39 grams/liter.
• the amount of total cell protein per volume of cell culture at an A600 of 1.0 for E. coli can be calculated as 215 ⁇ g total cell
• P. fluorescens like E. coli, is a gram- negative, rod-shaped bacterium.
• the percent of cell weight comprised by total cell protein for P. fluorescens HK44 is described as 55% by, e.g., Yarwood, et al., July 2002, "Noninvasive Quantitative Measurement of Bacterial Growth in Porous Media under Unsaturated-Flow Conditions," Applied and Environmental Microbiology 68(7):3597-3605. This percentage is similar to or the same as those given for E. coli by the references described above.
• the amount of soluble recombinant asparaginase is about 0.1% to about 95% of the total soluble protein produced in a culture. In embodiments, this amount is more than about 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% of the total soluble protein produced in a culture.
• this amount is about 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% of the total soluble protein produced in a culture.
• this amount is about 5% to about 95%, about 10% to about 85%, about 20% to about 75%, about 30% to about 65%, about 40% to about 55%, about 1% to about 95%, about 5% to about 30%, about 1% to about 10%, about 10% to about 20%, about 20% to about 30%, about 30% to about 40%, about 40% to about 50%, about 50 to about 60%, about 60% to about 70%, or about 80% to about 90% of the total soluble protein produced in a culture.
• the amount of soluble recombinant asparaginase, e.g., a monomelic or tetrameric type II asparaginase, produced is about 0.1% to about 50% of the dry cell weight (DCW). In embodiments, this amount is more than about 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, or 50% of DCW. In embodiments, this amount is about 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 45%, or 50% of DCW.
• DCW dry cell weight
• this amount is about 5% to about 50%, about 10% to about 40%, about 20% to about 30%, about 1% to about 20%, about 5% to about 25%, about 1% to about 10%, about 10% to about 20%, about 20% to about 30%, about 30% to about 40%, or about 40% to about 50% of the total soluble protein produced in a culture.
• Solubility and “activity” of a protein are generally determined by different means. Solubility of a protein, particularly a hydrophobic protein, indicates that hydrophobic amino acid residues are improperly located on the outside of the folded protein. Protein activity, which is often evaluated using different methods, e.g., as described below, is another indicator of proper protein conformation. "Soluble, active, or both” as used herein, refers to protein that is determined to be soluble, active, or both soluble and active, by methods known to those of skill in the art.
• Assays for evaluating asparaginase activity are known in the art and include but are not limited to fluorometric, colorometric, chemilumine scent, spectrophotometric, and other enzyme assays available to one of skill in the art. These assays can be used to compare activity or potency of an asparaginase preparation to a commercial or other asparaginase preparation.
• activity or potency is represented by the percent active protein in the extract supernatant as compared with the total amount assayed. This is based on the amount of protein determined to be active by the assay relative to the total amount of protein used in assay. In other embodiments, activity or potency is represented by the % activity or potency level of the protein compared to a standard or control protein. This is based on the amount of active protein in supernatant extract sample relative to the amount of active protein in a standard sample (where the same amount of protein from each sample is used in assay).
• the standard or control protein used in the activity or potency assay for comparison to a produced recombinant type II asparaginase is the active ingredient in Elspar®, or the active ingredient in any recombinant type II asparaginase product approved for clinical use and known in the art.
• the measured activity or potency of the recombinant type II asparaginase produced is compared with an activity or potency measured in the same amount of the standard or control type II asparaginase using the same method for measuring type II asparaginase activity.
• the measured activity or potency of the recombinant type II asparaginse produced is compared with an activity or potency measured in the same amount of a control type II asparaginase that has been commercially approved for use in patients.
• about 40% to about 100% of the recombinant asparaginase protein is determined to be active, soluble, or both. In embodiments, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, or about 100% of the recombinant asparaginase protein is determined to be active.
• about 40% to about 50%, about 50% to about 60%, about 60% to about 70%, about 70% to about 80%, about 80% to about 90%, about 90% to about 100%, about 50% to about 100%, about 60% to about 100%, about 70% to about 100%, about 80% to about 100%, about 40% to about 90%, about 40% to about 95%, about 50% to about 90%, about 50% to about 95%, about 50% to about 100%, about 60% to about 90%, about 60% to about 95%, about 60% to about 100%, about 70% to about 90%, about 70% to about 95%, about 70% to about 100%, or about 70% to about 100% of the recombinant asparaginase protein is determined to be active, soluble, or both.
• about 75% to about 100% of the recombinant asparaginase is determined to be active, soluble, or both.
• about 75% to about 80%, about 75% to about 85%, about 75% to about 90%, about 75% to about 95%, about 80% to about 85%, about 80% to about 90%, about 80% to about 95%, about 80% to about 100%, about 85% to about 90%, about 85% to about 95%, about 85% to about 100%, about 90% to about 95%, about 90% to about 100%, or about 95% to about 100% of the recombinant asparaginase is determined to be active, soluble, or both.
• a method of producing or expressing a recombinant type II asparaginase as described herein further comprises measuring the activity or potency of the recombinant type II asparaginase produced and comparing the measured activity or potency of the recombinant type II asparaginase produced with an activity or potency measured in the same amount of a control type II asparaginase using the same assay, wherein the measured activity or potency of the recombinant type II asparaginase produced is comparable to the activity or potency of the control type II asparaginase.
• comparable activity or potency is defined as 100% (which also can be expressed as 1.0), that is, when the activity or potency of the recombinant type II asparaginase produced and the control type II asparaginase are equal.
• the activity or potency of the recombinant type II asparaginase produced compared to the control type II asparaginase is about 80% to about 120%. In embodiments, the activity or potency is about 85% to about 1 15%. In embodiments, the activity or potency is about 90% to about 1 10%.
• the activity or potency is about 70% to about 130%. In embodiments, the activity or potency is about 65% to about 135%.
• the activity or potency of the recombinant type II asparaginase produced compared to the control type II asparaginase is about or at least about 65%, about or at least about 66%, about or at least about 67%, about or at least about 68%, about or at least about 69%, about or at least about 70%, about or at least about 71%, about or at least about 72%, about or at least about 73%, about or at least about 74%, about or at least about 75%, about or at least about 75%, about or at least about 76%, about or at least about 77%, about or at least about 78%, about or at least about 79%, about or at least about 80%, about or at least about 81%, about or at least about 82%, about or at least about 83%, about or at least about 84%, about or at least about 85%, about or at least about 86%, about or at least about 87%, about or at least about 88%, about or at least about 89%, about or at least about 90%, about or at least about 65%
• the activity or potency of the recombinant type II asparaginase produced compared to the control type II asparaginase is about 68% to about 132%, about 70% to about 130%, about 72% to about 128%, about 75% to about 125%, about 80% to about 120%, about 85% to about 1 15%, about 65% to about 110%, about 68% to about 1 10%, about 70% to about 1 10%, about 72% to about 1 10%, about 78% to about 110%, about 80% to about 110%, about 90% to about 1 10%, about 95% to about 105%, about 85% to about 1 10%, about 90% to about 1 10%, about 95% to about 1 10%, about 96% to about 1 10%, about 97% to about 1 10%, about 98% to about 1 10%, about 99% to about 1 10%, about 100% to about 1 10%, about 65% to about 105%, about 68% to about 105%, about 70% to about 105%, about 72% to about 105%, about 80% to about 105%, about 85% to about 105%,
• the E. coli A-l -3 L-asparaginase II gene was optimized for expression in P. fluorescens and cloned into a set of expression vectors for cytoplasmic and periplasmic expression.
• the amino acid sequence used is disclosed herein as SEQ ID NO: 1.
• the nucleic acid sequence used is disclosed herein as SEQ ID NO: 2.
• Each construct was transformed into P. fluorescens host strains DC454 (pyrF deficient, no PD or FMO) and DC441 ⁇ pyrF, Lon, and HslUV deficient), and the resulting expression strains were evaluated for ?, coli A-l -3 L-asparaginase II production in 0.5 mL cultures. The whole broth was sonicated, centrifuged, and the soluble fractions analyzed by CGE.
• ligation mixtures for each of the E. coli A-l -3 L- asparaginase II expression plasmids were transformed into P. fluorescens host strains DC454 and DC441 cells as follows. Twenty-five microliters of competent cells were thawed and transferred into a 96- multiwell Nucleovette® plate (Lonza VHNP-1001), and ligation mixture was added to each well. Cells were electroporated using the NucleofectorTM 96-well ShuttleTM system (Lonza AG). Cells were then transferred to 96-well deep well plates with 400 ⁇ M9 salts 1% glucose medium and trace elements.
• the 96-well plates were incubated at 30 °C with shaking for 48 hours. Ten microliters of seed culture were transferred in duplicate into 96-well deep well plates, each well containing 500 ⁇ of HTP medium, supplemented with trace elements and 5% glycerol, and incubated as before, for 24 hours. Isopropyl- -D-l-thiogalactopyranoside (IPTG) was added at the 24-hour time point to each well for a final concentration of 0.3 mM, to induce the expression of target proteins. Mannitol (Sigma, M1902) was added to each well for a final concentration of 1% to induce the expression of folding modulators in folding modulator overexpressing strains.
• IPTG Isopropyl- -D-l-thiogalactopyranoside
• Cell density was measured by optical density at 600 nm (OD600) at 24 hours after induction to monitor growth. Twenty-four hours after induction, cells were harvested, diluted 1 :3 in IX PBS for a final volume of 400 ⁇ 1, then frozen. Samples were prepared and analyzed as described below.
• expression plasmids selected based on the expression plasmid screening results each were transformed into each of 24 P. fluorescens host strains in an array, including the wild-type (WT) or parent DC454 strain, protease deletion (PD) strains, folding modulator overexpressing (FMO) strains and protease deletion plus folding modulator overexpressor (PD/FMO) strains.
• WT wild-type
• PD protease deletion
• FMO folding modulator overexpressing
• PD/FMO protease deletion plus folding modulator overexpressor
• E. coli asparaginase fused to the P. fluorescens aparaginase secretion leader (AnsB) was included in the array (amino acid sequence set forth as SEQ ID NO: 14; coding sequence set forth as SEQ ID NO: 15).
• Folding modulators, when present, were encoded on a second plasmid and expression was driven by a P. fluorescens-native
• transformations were performed as follows: twenty-five microliters of P. fluorescens host strain competent cells were thawed and transferred into a 96-multi-well Nucleovette® plate, and 10 ⁇ plasmid DNA (10 ng) was added to each well. The cells were electroporated, cultured, induced in HTP format and harvested as described for the plasmid expression screening above. Samples were prepared and analyzed as described below.
• Soluble fractions were prepared by sonication followed by centrifugation.
• Culture broth samples 400 ⁇
• the lysates were centrifuged at 5,500 x g for 15 minutes (4 °C) and the supernatants collected (soluble fraction).
• Protein samples were analyzed by microchip SDS capillary gel electrophoresis using a LabChip GXII instrument (PerkinElmer) with a HT Protein Express chip and corresponding reagents (part numbers 760528 and CLS760675, respectively, PerkinElmer). Samples were prepared following the manufacturer's protocol (Protein User Guide Document No. 450589, Rev. 3). Briefly, in a 96-well polypropylene conical well PCR plate, 4 ⁇ ⁇ of sample were mixed with 14 ⁇ ⁇ of sample buffer, with 70 mM DTT reducing agent, heated at
• a commercially available L-asparaginase activity assay kit (Sigma) detected significant L- asparaginase activity in HTP culture lysate samples from top yielding strain STR55382 (Lao leader) when compared to a Null sample.
• SDS-CGE quantification was done using Sigma E. coli L- Asp2 standard curve. Production of greater than 1 g/L soluble monomer was observed.
• An exemplary SDS-CGE image of 5 x diluted samples is provided in FIG. 2. [00135] The last row of Table 8 shows the expression results for a strain expressing the native P.
• a BLAST search of the P. fluorescens MB214 genome sequence using the asparaginase protein amino acid sequence as input resulted in output of two protein encoding genes (pegs) showing significant alignment: peg.3886 (L-asparaginase EC 3.5.1.1 type II, SEQ ID NO: 54) and peg.5048 (L-asparaginase EC 3.5.1.1, SEQ ID NO: 55).
• a cloned deletion construct for each native L-asparaginase gene was initiated by synthesizing DNA sequence fragments that contain a fusion of upstream and downstream flanking regions for each gene leaving only the start and stop codons of the gene targeted for deletion. These fragments were subsequently blunt-end ligated into the Srfl site of vector pDOW1261-24 to produce deletion plasmids pFNX3970 and pFNX3969, respectively.
• the ligation reaction was subsequently transformed into E. coli DH5alpha cells (Thermo Scientific) to isolate colonies and purify successfully cloned deletion plasmid DNA.
• the deletion plasmid was electroporated into a P. fluorescens host strain which contains a chromosomal deletion in the pyrF gene involved in uracil (pyrimidine) biosynthesis.
• the deletion plasmid contains the PyrF coding sequence but is unable to replicate in P. fluorescens cells.
• the electroporated cells were plated onto M9 salts agar plates supplemented with 1% glucose and 250 ug/mL proline (if the host strain is a proline auxotroph).
• the resulting clones are able to synthesize uracil due to an integration event that recombines the entire deletion plasmid into the chromosome at one of the two homologous regions within the genome.
• plasmid integrant strains were grown to stationary phase in 3 mL LB medium supplemented with 250 ug/mL uracil and 250 ug/mL proline (if the host strain is a proline auxotroph).
• PF1433 (PyrF, AspGl, and AspG2 deficient), was constructed by sequential deletion of the aspG2 and aspGl genes in the host strain DC454 (PyrF deficient).
• PF1434 (PyrF, ProC, AspGl, and AspG2 deficient), was constructed by sequential deletion of the aspGl and aspG2 genes in the host strain DC455 (pyrF proC). Strain DC455 is the parent strain of both DC542 and DC549.
• PF1442 (PyrF, ProC, AspGl, AspG2, Lon, DegPl, DegP2 S219A, Prcl, and AprA deficient), was constructed by sequential deletion of aspG2 and aspGl in the host strain PF1201 (PyrF, ProC, proteases Lon, DegPl, DegP2 S219A, Prcl, and AprA deficient).
• PF1443 (PyrF, ProC, AspGl, and AspG2 deficient; FMO LepB in pDOW3700), was constructed by transformation of the lepB encoding FMO plasmid pDOW3700 into PF1434.
• PF1444 (PyrF, ProC, AspGl, and AspG2 deficient; FMO Tig in pDOW3707), was constructed by transformation of the Tig encoding FMO plasmid pDOW3703 into PF1434.
• PF1445 (PyrF, ProC, AspGl, AspG2, Lon, DegPl, DegP2, S219A, Prcl, and AprA deficient;
• FMO DsbAC-Skp in pFNX4142 was constructed by the transformation of PF 1442 with the DsbAC-Skp encoding plasmid pFNX4142.
• the fed-batch high cell density fermentation process consisted of a growth phase followed by an induction phase, initiated by the addition of IPTG and 5 g/L mannitol once the culture reached the target biomass (wet cell weight).
• the conditions during the induction phase were varied according to the experimental design.
• the induction phase of the fermentation was allowed to proceed for approximately 24 hours.
• Analytical samples were withdrawn from the fermentor to determine cell density (optical density at 575 nm) and were then frozen for subsequent analyses to determine the level of target gene expression.
• the whole fermentation broth of each vessel was harvested by centrifugation at 15,900 x g for 60 to 90 minutes.
• the cell paste and supernatant were separated and the paste retained and frozen at -80 °C.
• Table 12 shows expression results with strains STR57863 and STR57860 under several fermentation conditions. As shown, several of the initial strain/fermentation condition combinations resulted in >30% TCP asparaginase expression. Total cell protein was calculated as follows:
• TCP at the final timepoint (124) OD575 * 275mg/L TCP
• Additional strains constructed as described herein, e.g., additional strains described in Example 3, are scaled to 2 L fermentation and each screened under different fermentation conditions in a manner similar to that described in Example 4.
• Type II amino FVITHG DTMEE AYFLDL VKCDKPVVMVGAMRPS SMSADGPFNLYNAVV acid sequence TAADKASA RGVLVVMNDTVLDGRDVTKTNTTDVATFKSVNYGPLGYIHNGK
• Ttg2C secretion ATGCAAAACCGCACTGTGGAAATCGGTGTCGGCCTTTTCTTGCTGGCTGGCA 32 leader nucleic TCCTGGCTTTACTGTTGTTGGCCCTGCGAGTCAGCGGCCTTTCGGCC

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