EP1151111A2 - Adp-glukose modifikatoren - Google Patents
Adp-glukose modifikatorenInfo
- Publication number
- EP1151111A2 EP1151111A2 EP00910141A EP00910141A EP1151111A2 EP 1151111 A2 EP1151111 A2 EP 1151111A2 EP 00910141 A EP00910141 A EP 00910141A EP 00910141 A EP00910141 A EP 00910141A EP 1151111 A2 EP1151111 A2 EP 1151111A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- isolated polynucleotide
- polypeptide
- nucleic acid
- sequences
- seq
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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- 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
- C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
- C12N15/82—Vectors or expression systems specially adapted for eukaryotic hosts for plant cells, e.g. plant artificial chromosomes (PACs)
- C12N15/8241—Phenotypically and genetically modified plants via recombinant DNA technology
- C12N15/8242—Phenotypically and genetically modified plants via recombinant DNA technology with non-agronomic quality (output) traits, e.g. for industrial processing; Value added, non-agronomic traits
- C12N15/8243—Phenotypically and genetically modified plants via recombinant DNA technology with non-agronomic quality (output) traits, e.g. for industrial processing; Value added, non-agronomic traits involving biosynthetic or metabolic pathways, i.e. metabolic engineering, e.g. nicotine, caffeine
- C12N15/8245—Phenotypically and genetically modified plants via recombinant DNA technology with non-agronomic quality (output) traits, e.g. for industrial processing; Value added, non-agronomic traits involving biosynthetic or metabolic pathways, i.e. metabolic engineering, e.g. nicotine, caffeine involving modified carbohydrate or sugar alcohol metabolism, e.g. starch biosynthesis
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- 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
- C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
- C12N15/82—Vectors or expression systems specially adapted for eukaryotic hosts for plant cells, e.g. plant artificial chromosomes (PACs)
- C12N15/8201—Methods for introducing genetic material into plant cells, e.g. DNA, RNA, stable or transient incorporation, tissue culture methods adapted for transformation
- C12N15/8209—Selection, visualisation of transformants, reporter constructs, e.g. antibiotic resistance markers
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- 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
- C12N9/10—Transferases (2.)
- C12N9/12—Transferases (2.) transferring phosphorus containing groups, e.g. kinases (2.7)
- C12N9/1241—Nucleotidyltransferases (2.7.7)
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- 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
- C12N9/90—Isomerases (5.)
Definitions
- This invention is in the field of plant molecular biology. More specifically, this invention pertains to nucleic acid fragments encoding UDP-glucose modifiers in plants and seeds.
- UDP glucose pyrophosphorylase (EC 2.7.7.9) is also called UTP-glucose-1 -phosphate uridylyltransferase or glucose- 1 -phosphate uridylyltransferase. It catalyzes the interconversion of G-l-P and UDP-Glucose important in starch, pectin, and hemicellulose biosynthesis.
- UDP glucose pyrophosphorylase catalyzes a phosphoanhydride exchange reaction in which the phosphoryl oxygen from glucose 1 -phosphate attacks the alpha phosphorus atom from UTP to form UDP glucose and release pyrophosphate which is rapidly hydrolyzed.
- At least two mRN A populations of UDP-glucose pyrophosphorylase are present in most European potato cultivars. These isozymes are highly active and appear to be dimeric in nature. The two cDNA populations are related to a potato cultivar's ability to resist sweetening when exposed to cold temperatures (Sowokinos et al. (1997) Plant Physiol. 773:511-517). UDP-glucose pyrophosphorylase mRN A levels are reduced in response to "long term" stomatal opening and closing responses to environmental stress caused in planta by withholding water over a period of 2-4 days (Kopka et al. (1997) Plant J. 77:871-882).
- the present invention relates to isolated polynucleotides comprising a nucleotide sequence encoding a polypeptide of at least 100 amino acids that has at least 100% identity based on the Clustal method of alignment when compared to a UDP glucose pyrophosphorylase polypeptide selected from the group consisting SEQ ID NOs:2, 4, 6, 8, 10, and 12.
- the present invention also relates to an isolated polynucleotide comprising the complement of the nucleotide sequences described above.
- the isolated polynucleotide of the claimed invention consists of a nucleic acid sequence selected from the group consisting of SEQ ID NOs:l, 3, 5, 7, 9, and 11 that codes for the polypeptide selected from the group consisting of SEQ ID NOs:2, 4, 6, 8, 10, and 12.
- the present invention also relates to an isolated polynucleotide comprising a nucleotide sequences of at least one of 60 (preferably at least one of 40, most preferably at least one of 30) contiguous nucleotides derived from a nucleotide sequence selected from the group consisting of SEQ ID NOs: 1 , 3, 5, 7, 9, and 11 and the complement of such nucleotide sequences.
- the present invention relates to a chimeric gene comprising an isolated polynucleotide of the present invention operably linked to suitable regulatory sequences.
- the present invention relates to an isolated host cell comprising a chimeric gene of the present invention or an isolated polynucleotide of the present invention.
- the host cell may be eukaryotic, such as a yeast or a plant cell, or prokaryotic, such as a bacterial cell.
- the present invention also relates to a virus, preferably a baculovirus, comprising an isolated polynucleotide of the present invention or a chimeric gene of the present invention.
- the present invention relates to a process for producing an isolated host cell comprising a chimeric gene of the present invention or an isolated polynucleotide of the present invention, the process comprising either transforming or transfecting an isolated compatible host cell with a chimeric gene or isolated polynucleotide of the present invention.
- the present invention relates to a UDP glucose pyrophosphorylase polypeptide of at least 100 amino acids comprising at least 100% homology based on the Clustal method of alignment compared to a polypeptide selected from the group consisting of SEQ ID NOs:2, 4, 6, 8, 10, and 12.
- the present invention relates to a method of selecting an isolated polynucleotide that affects the level of expression of a UDP glucose pyrophosphorylase polypeptide in a host cell, preferably a plant cell, the method comprising the steps of: (a) constructing an isolated polynucleotide of the present invention or an isolated chimeric gene of the present invention; (b) introducing the isolated polynucleotide or the isolated chimeric gene into a host cell; (c) measuring the level a UDP glucose pyrophosphorylase polypeptide in the host cell containing the isolated polynucleotide; and (d) comparing the level of a UDP glucose pyrophosphorylase polypeptide in the host cell containing the isolated polynucleotide with the level of a UDP glucose pyrophosphorylase polypeptide in the host cell that does not contain the isolated polynucleotide.
- the present invention relates to a method of obtaining a nucleic acid fragment encoding a substantial portion of a UDP glucose pyrophosphorylase polypeptide, preferably a plant UDP glucose pyrophosphorylase polypeptide, comprising the steps of : synthesizing an oligonucleotide primer comprising a nucleotide sequence of at least one of 60 (preferably at least one of 40, most preferably at least one of 30) contiguous nucleotides derived from a nucleotide sequence selected from the group consisting of SEQ ID NOs:l, 3, 5, 7, 9, and 11 and the complement of such nucleotide sequences; and amplifying a nucleic acid fragment (preferably a cDNA inserted in a cloning vector) using the oligonucleotide primer.
- the amplified nucleic acid fragment preferably will encode a portion of a UDP glucose pyrophosphorylase amino acid sequence.
- the present invention also relates to a method of obtaining a nucleic acid encoding all or a substantial portion of the amino acid sequence of a UDP glucose pyrophosphorylase polypeptide comprising the steps of: probing a cDNA or genomic library with an isolated polynucleotide of the present invention; identifying a DNA clone that hybridizes with an isolated polynucleotide of the present invention; isolating the identified DNA clone; and sequencing the cDNA or genomic fragment that comprises the isolated DNA clone.
- the present invention relates to a composition, such as a hybridization mixture, comprising an isolated polynucleotide of the present invention.
- the present invention relates to an isolated polynucleotide of the present invention comprising at least one of 30 contiguous nucleotides derived from a nucleic acid sequence selected from the group consisting of SEQ ID NOs:l, 3, 5, 7, 9, and 11.
- the present invention relates to an expression cassette comprising an isolated polynucleotide of the present invention operably linked to a promoter.
- the present invention relates to a method for positive selection of a transformed cell comprising: (a) transforming a host cell with the chimeric gene of the present invention or an expression cassette of the present invention; and (b) growing the transformed host cell, preferably plant cell, such as a monocot or a dicot, under conditions which allow expression of the UDP glucose pyrophosphorylase polynucleotide in an amount sufficient to complement a null mutant to provide a positive selection means.
- Figure 1 depicts the amino acid sequence alignment between the UDP glucose pyrophosphorylase from corn (clone p0006.cbyvq06rb; SEQ ID NO:2), soybean (clone sdp3c.pk013.121; SEQ ID NO: 10), wheat (clone wleln.pk0063.d7; SEQ ID NO:12) and Hordeum vulgare (NCBI General Identifier No. 2117937 or 6136111; SEQ ID NO:13). Amino acids which are conserved among all sequences are indicated with an asterisk (*) above the alignment. Dashes are used by the program to maximize the alignment.
- Table 1 lists the polypeptides that are described herein, the designation of the cDNA clones that comprise the nucleic acid fragments encoding polypeptides representing all or a substantial portion of these polypeptides, and the corresponding identifier (SEQ ID NO:) as used in the attached Sequence Listing.
- the sequence descriptions and Sequence Listing attached hereto comply with the rules governing nucleotide and/or amino acid sequence disclosures in patent applications as set forth in 37 C.F.R. ⁇ 1.821-1.825. TABLE 1 UDP Glucose Pyrophosphorylase
- a "polynucleotide” is a nucleotide sequence such as a nucleic acid fragment.
- a polynucleotide may be a polymer of RNA or DNA that is single- or double-stranded, that optionally contains synthetic, non-natural or altered nucleotide bases.
- a polynucleotide in the form of a polymer of DNA may be comprised of one or more segments of cDNA, genomic DNA, synthetic DNA, or mixtures thereof.
- An isolated polynucleotide of the present invention may include at least one of 60 contiguous nucleotides, preferably at least one of 40 contiguous nucleotides, most preferably one of at least 30 contiguous nucleotides derived from SEQ ID NOs:l, 3, 5, 7, 9, and 11, or the complement of such sequences.
- "contig” refers to a nucleotide sequence that is assembled from two or more constituent nucleotide sequences that share common or overlapping regions of sequence homology. For example, the nucleotide sequences of two or more nucleic acid fragments can be compared and aligned in order to identify common or overlapping sequences. Where common or overlapping sequences exist between two or more nucleic acid fragments, the sequences (and thus their corresponding nucleic acid fragments) can be assembled into a single contiguous nucleotide sequence.
- substantially similar refers to nucleic acid fragments wherein changes in one or more nucleotide bases results in substitution of one or more amino acids, but do not affect the functional properties of the polypeptide encoded by the nucleotide sequence. “Substantially similar” also refers to nucleic acid fragments wherein changes in one or more nucleotide bases does not affect the ability of the nucleic acid fragment to mediate alteration of gene expression by gene silencing through for example antisense or co-suppression technology.
- Substantially similar also refers to modifications of the nucleic acid fragments of the instant invention such as deletion or insertion of one or more nucleotides that do not substantially affect the functional properties of the resulting transcript vis-a-vis the ability to mediate gene silencing or alteration of the functional properties of the resulting protein molecule. It is therefore understood that the invention encompasses more than the specific exemplary nucleotide or amino acid sequences and includes functional equivalents thereof.
- Substantially similar nucleic acid fragments may be selected by screening nucleic acid fragments representing subfragments or modifications of the nucleic acid fragments of the instant invention, wherein one or more nucleotides are substituted, deleted and/or inserted, for their ability to affect the level of the polypeptide encoded by the unmodified nucleic acid fragment in a plant or plant cell.
- a substantially similar nucleic acid fragment representing at least one of 30 contiguous nucleotides derived from the instant nucleic acid fragment can be constructed and introduced into a plant or plant cell.
- the level of the polypeptide encoded by the unmodified nucleic acid fragment present in a plant or plant cell exposed to the substantially similar nucleic fragment can then be compared to the level of the polypeptide in a plant or plant cell that is not exposed to the substantially similar nucleic acid fragment.
- antisense suppression and co-suppression of gene expression may be accomplished using nucleic acid fragments representing less than the entire coding region of a gene, and by nucleic acid fragments that do not share 100% sequence identity with the gene to be suppressed.
- alterations in a nucleic acid fragment which result in the production of a chemically equivalent amino acid at a given site, but do not effect the functional properties of the encoded polypeptide are well known in the art.
- a codon for the amino acid alanine, a hydrophobic amino acid may be substituted by a codon encoding another less hydrophobic residue, such as glycine, or a more hydrophobic residue, such as valine, leucine, or isoleucine.
- a codon encoding another less hydrophobic residue such as glycine
- a more hydrophobic residue such as valine, leucine, or isoleucine.
- changes which result in substitution of one negatively charged residue for another such as aspartic acid for glutamic acid, or one positively charged residue for another, such as lysine for arginine, can also be expected to produce a functionally equivalent product.
- Nucleotide changes which result in alteration of the N-terminal and C-terminal portions of the polypeptide molecule would also not be expected to alter the activity of the polypeptide.
- an isolated polynucleotide comprising a nucleotide sequence of at least one of 60 (preferably at least one of 40, most preferably at least one of 30) contiguous nucleotides derived from a nucleotide sequence selected from the group consisting of SEQ ID NOs:l, 3, 5, 7, 9, and 11 and the complement of such nucleotide sequences may be used in methods of selecting an isolated UDP glucose pyrophosphorylase polynucleotide that affects the expression of a UDP glucose pyrophosphorylase polypeptide in a host cell.
- a method of selecting an isolated polynucleotide that affects the level of expression of a polypeptide in a host cell may comprise the steps of: constructing an isolated polynucleotide of the present invention or an isolated chimeric gene of the present invention; introducing the isolated polynucleotide or the isolated chimeric gene into a host cell; measuring the level a polypeptide in the host cell containing the isolated polynucleotide; and comparing the level of a polypeptide in the host cell containing the isolated polynucleotide with the level of a polypeptide in a host cell that does not contain the isolated polynucleotide.
- substantially similar nucleic acid fragments may also be characterized by their ability to hybridize. Estimates of such homology are provided by either DNA-DNA or DNA-RNA hybridization under conditions of stringency as is well understood by those skilled in the art (Hames and Higgins, Eds. (1985) Nucleic Acid Hybridisation, IRL Press, Oxford, U.K.). Stringency conditions can be adjusted to screen for moderately similar fragments, such as homologous sequences from distantly related organisms, to highly similar fragments, such as genes that duplicate functional enzymes from closely related organisms. Post-hybridization washes determine stringency conditions.
- One set of preferred conditions uses a series of washes starting with 6X SSC, 0.5% SDS at room temperature for 15 min, then repeated with 2X SSC, 0.5% SDS at 45°C for 30 min, and then repeated twice with 0.2X SSC, 0.5% SDS at 50°C for 30 min.
- a more preferred set of stringent conditions uses higher temperatures in which the washes are identical to those above except for the temperature of the final two 30 min washes in 0.2X SSC, 0.5% SDS was increased to 60°C.
- Another preferred set of highly stringent conditions uses two final washes in 0.1X SSC, 0.1% SDS at 65°C.
- nucleic acid fragments of the instant invention may also be characterized by the percent identity of the amino acid sequences that they encode to the amino acid sequences disclosed herein, as determined by algorithms commonly employed by those skilled in this art.
- Suitable nucleic acid fragments encode polypeptides that are at least about 70%) identical, preferably at least about 80% identical to the amino acid sequences reported herein.
- Preferred nucleic acid fragments encode amino acid sequences that are about 85% identical to the amino acid sequences reported herein. More preferred nucleic acid fragments encode amino acid sequences that are at least about 90% identical to the amino acid sequences reported herein.
- nucleic acid fragments that encode amino acid sequences that are at least about 95%o identical to the amino acid sequences reported herein. Suitable nucleic acid fragments not only have the above homologies but typically encode a polypeptide having at least 50 amino acids, preferably at least 100 amino acids, more preferably at least 150 amino acids, still more preferably at least 200 amino acids, and most preferably at least 250 amino acids. Sequence alignments and percent identity calculations were performed using the Megalign program of the LASERGENE bioinformatics computing suite (DNASTAR Inc., Madison, WI). Multiple alignment of the sequences was performed using the Clustal method of alignment (Higgins and Sharp (1989) CABIOS.
- a "substantial portion" of an amino acid or nucleotide sequence comprises an amino acid or a nucleotide sequence that is sufficient to afford putative identification of the protein or gene that the amino acid or nucleotide sequence comprises.
- Amino acid and nucleotide sequences can be evaluated either manually by one skilled in the art, or by using computer- based sequence comparison and identification tools that employ algorithms such as BLAST (Basic Local Alignment Search Tool; Altschul et al. (1993) J. Mol. Biol. 275:403-410; see also www.ncbi.nlm.nih.gov/BLAST/).
- a sequence often or more contiguous amino acids or thirty or more contiguous nucleotides is necessary in order to putatively identify a polypeptide or nucleic acid sequence as homologous to a known protein or gene.
- gene-specific oligonucleotide probes comprising 30 or more contiguous nucleotides may be used in sequence-dependent methods of gene identification (e.g., Southern hybridization) and isolation (e.g., in situ hybridization of bacterial colonies or bacteriophage plaques).
- oligonucleotides of 12 or more nucleotides may be used as amplification primers in PCR in order to obtain a particular nucleic acid fragment comprising the primers.
- a "substantial portion" of a nucleotide sequence comprises a nucleotide sequence that will afford specific identification and/or isolation of a nucleic acid fragment comprising the sequence.
- the instant specification teaches amino acid and nucleotide sequences encoding polypeptides that comprise one or more particular plant proteins. The skilled artisan, having the benefit of the sequences as reported herein, may now use all or a substantial portion of the disclosed sequences for purposes known to those skilled in this art.
- the instant invention comprises the complete sequences as reported in the accompanying Sequence Listing, as well as substantial portions of those sequences as defined above.
- "Codon degeneracy” refers to divergence in the genetic code permitting variation of the nucleotide sequence without effecting the amino acid sequence of an encoded polypeptide.
- the instant invention relates to any nucleic acid fragment comprising a nucleotide sequence that encodes all or a substantial portion of the amino acid sequences set forth herein.
- the skilled artisan is well aware of the "codon-bias" exhibited by a specific host cell in usage of nucleotide codons to specify a given amino acid. Therefore, when synthesizing a nucleic acid fragment for improved expression in a host cell, it is desirable to design the nucleic acid fragment such that its frequency of codon usage approaches the frequency of preferred codon usage of the host cell.
- Synthetic nucleic acid fragments can be assembled from oligonucleotide building blocks that are chemically synthesized using procedures known to those skilled in the art. These building blocks are ligated and annealed to form larger nucleic acid fragments which may then be enzymatically assembled to construct the entire desired nucleic acid fragment. "Chemically synthesized”, as related to nucleic acid fragment, means that the component nucleotides were assembled in vitro. Manual chemical synthesis of nucleic acid fragments may be accomplished using well established procedures, or automated chemical synthesis can be performed using one of a number of commercially available machines.
- nucleic acid fragments can be tailored for optimal gene expression based on optimization of nucleotide sequence to reflect the codon bias of the host cell.
- the skilled artisan appreciates the likelihood of successful gene expression if codon usage is biased towards those codons favored by the host. Determination of preferred codons can be based on a survey of genes derived from the host cell where sequence information is available.
- Gene refers to a nucleic acid fragment that expresses a specific protein, including regulatory sequences preceding (5' non-coding sequences) and following (3' non-coding sequences) the coding sequence.
- Native gene refers to a gene as found in nature with its own regulatory sequences.
- Chimeric gene refers any gene that is not a native gene, comprising regulatory and coding sequences that are not found together in nature. Accordingly, a chimeric gene may comprise regulatory sequences and coding sequences that are derived from different sources, or regulatory sequences and coding sequences derived from the same source, but arranged in a manner different than that found in nature.
- Endogenous gene refers to a native gene in its natural location in the genome of an organism.
- a “foreign” gene refers to a gene not normally found in the host organism, but that is introduced into the host organism by gene transfer. Foreign genes can comprise native genes inserted into a non-native organism, or chimeric genes.
- a “transgene” is a gene that has been introduced into the genome by a transformation procedure.
- Coding sequence refers to a nucleotide sequence that codes for a specific amino acid sequence.
- Regulatory sequences refer to nucleotide sequences located upstream (5' non- coding sequences), within, or downstream (3' non-coding sequences) of a coding sequence, and which influence the transcription, RNA processing or stability, or translation of the associated coding sequence. Regulatory sequences may include promoters, translation leader sequences, introns, and polyadenylation recognition sequences.
- Promoter refers to a nucleotide sequence capable of controlling the expression of a coding sequence or functional RNA. In general, a coding sequence is located 3' to a promoter sequence.
- the promoter sequence consists of proximal and more distal upstream elements, the latter elements often referred to as enhancers.
- an "enhancer” is a nucleotide sequence which can stimulate promoter activity and may be an innate element of the promoter or a heterologous element inserted to enhance the level or tissue-specificity of a promoter. Promoters may be derived in their entirety from a native gene, or be composed of different elements derived from different promoters found in nature, or even comprise synthetic nucleotide segments. It is understood by those skilled in the art that different promoters may direct the expression of a gene in different tissues or cell types, or at different stages of development, or in response to different environmental conditions.
- Promoters which cause a nucleic acid fragment to be expressed in most cell types at most times are commonly referred to as "constitutive promoters". New promoters of various types useful in plant cells are constantly being discovered; numerous examples may be found in the compilation by Okamuro and Goldberg (1989) Biochemistry of Plants 75: 1 -82. It is further recognized that since in most cases the exact boundaries of regulatory sequences have not been completely defined, nucleic acid fragments of different lengths may have identical promoter activity.
- the "translation leader sequence” refers to a nucleotide sequence located between the promoter sequence of a gene and the coding sequence.
- the translation leader sequence is present in the fully processed mRNA upstream of the translation start sequence.
- the translation leader sequence may affect processing of the primary transcript to mRNA, mRNA stability or translation efficiency. Examples of translation leader sequences have been described (Turner and Foster (1995) Mol. Biotechnol. 3:225-236).
- the "3' non-coding sequences” refer to nucleotide sequences located downstream of a coding sequence and include polyadenylation recognition sequences and other sequences encoding regulatory signals capable of affecting mRNA processing or gene expression.
- the polyadenylation signal is usually characterized by affecting the addition of polyadenylic acid tracts to the 3' end of the mRNA precursor.
- the use of different 3' non-coding sequences is exemplified by Ingelbrecht et al. (1989) Plant Cell 1 :671-680.
- RNA transcript refers to the product resulting from RNA polymerase-catalyzed transcription of a DNA sequence. When the RNA transcript is a perfect complementary copy of the DNA sequence, it is referred to as the primary transcript or it may be a RNA sequence derived from posttranscriptional processing of the primary transcript and is referred to as the mature RNA.
- Messenger RNA (mRNA) refers to the RNA that is without introns and that can be translated into polypeptide by the cell.
- cDNA refers to a double-stranded DNA that is complementary to and derived from mRNA.
- Sense RNA refers to an RNA transcript that includes the mRNA and so can be translated into a polypeptide by the cell.
- Antisense RNA refers to an RNA transcript that is complementary to all or part of a target primary transcript or mRNA and that blocks the expression of a target gene (see U.S. Patent No. 5,107,065, incorporated herein by reference).
- the complementarity of an antisense RNA may be with any part of the specific nucleotide sequence, i.e., at the 5' non-coding sequence, 3' non-coding sequence, introns, or the coding sequence.
- “Functional RNA” refers to sense RNA, antisense RNA, ribozyme RNA, or other RNA that may not be translated but yet has an effect on cellular processes.
- operably linked refers to the association of two or more nucleic acid fragments on a single nucleic acid fragment so that the function of one is affected by the other.
- a promoter is operably linked with a coding sequence when it is capable of affecting the expression of that coding sequence (i.e., that the coding sequence is under the transcriptional control of the promoter).
- Coding sequences can be operably linked to regulatory sequences in sense or antisense orientation.
- expression refers to the transcription and stable accumulation of sense (mRNA) or antisense RNA derived from the nucleic acid fragment of the invention. Expression may also refer to translation of mRNA into a polypeptide.
- Antisense inhibition refers to the production of antisense RNA transcripts capable of suppressing the expression of the target protein.
- Overexpression refers to the production of a gene product in transgenic organisms that exceeds levels of production in normal or non-transformed organisms.
- Co-suppression refers to the production of sense RNA transcripts capable of suppressing the expression of identical or substantially similar foreign or endogenous genes (U.S. Patent No. 5,231,020, incorporated herein by reference).
- altered levels refers to the production of gene product(s) in transgenic organisms in amounts or proportions that differ from that of normal or non-transformed organisms.
- “Mature” protein refers to a post-translationally processed polypeptide; i.e., one from which any pre- or propeptides present in the primary translation product have been removed.
- Precursor protein refers to the primary product of translation of mRNA; i.e., with pre- and propeptides still present. Pre- and propeptides may be but are not limited to intracellular localization signals.
- Transformation refers to the transfer of a nucleic acid fragment into the genome of a host organism, resulting in genetically stable inheritance.
- transgenic organisms containing the transformed nucleic acid fragments are referred to as "transgenic" organisms.
- methods of plant transformation include ⁇ grob ete ⁇ wm-mediated transformation (De Blaere et al. (1987) Meth. Enzymol. 143:277) and particle-accelerated or "gene gun” transformation technology (Klein et al. (1987) Nature (London) 327:70-73; U.S. Patent No. 4,945,050, incorporated herein by reference).
- Nucleic acid fragments encoding at least a portion of several UDP-glucose modifying enzymes have been isolated and identified by comparison of random plant cDNA sequences to public databases containing nucleotide and protein sequences using the BLAST algorithms well known to those skilled in the art.
- the nucleic acid fragments of the instant invention may be used to isolate cDNAs and genes encoding homologous proteins from the same or other plant species. Isolation of homologous genes using sequence-dependent protocols is well known in the art.
- sequence-dependent protocols include, but are not limited to, methods of nucleic acid hybridization, and methods of DNA and RNA amplification as exemplified by various uses of nucleic acid amplification technologies (e.g., polymerase chain reaction, ligase chain reaction).
- genes encoding other UDP glucose pyrophosphorylases could be isolated directly by using all or a portion of the instant nucleic acid fragments as DNA hybridization probes to screen libraries from any desired plant employing methodology well known to those skilled in the art.
- Specific oligonucleotide probes based upon the instant nucleic acid sequences can be designed and synthesized by methods known in the art (Maniatis).
- the entire sequences can be used directly to synthesize DNA probes by methods known to the skilled artisan such as random primer DNA labeling, nick translation, or end-labeling techniques, or RNA probes using available in vitro transcription systems.
- primers can be designed and used to amplify a part or all of the instant sequences.
- the resulting amplification products can be labeled directly during amplification reactions or labeled after amplification reactions, and used as probes to isolate full length cDNA or genomic fragments under conditions of appropriate stringency.
- two short segments of the instant nucleic acid fragments may be used in polymerase chain reaction protocols to amplify longer nucleic acid fragments encoding homologous genes from DNA or RNA.
- the polymerase chain reaction may also be performed on a library of cloned nucleic acid fragments wherein the sequence of one primer is derived from the instant nucleic acid fragments, and the sequence of the other primer takes advantage of the presence of the polyadenylic acid tracts to the 3' end of the mRNA precursor encoding plant genes.
- the second primer sequence may be based upon sequences derived from the cloning vector. For example, the skilled artisan can follow the RACE protocol (Frohman et al. (1988) Proc. Natl.
- a polynucleotide comprising a nucleotide sequence of at least one of 60 (preferably one of at least 40, most preferably one of at least 30) contiguous nucleotides derived from a nucleotide sequence selected from the group consisting of SEQ ID NOs: 1, 3, 5, 7, 9, and 11 and the complement of such nucleotide sequences may be used in such methods to obtain a nucleic acid fragment encoding a substantial portion of an amino acid sequence of a polypeptide.
- the present invention relates to a method of obtaining a nucleic acid fragment encoding a substantial portion of a UDP glucose pyrophosphorylase polypeptide preferably a substantial portion of a plant UDP glucose pyrophosphorylase polypeptide, comprising the steps of : synthesizing an oligonucleotide primer comprising a nucleotide sequence of at least one of 60 (preferably at least one of 40, most preferably at least one of 30) contiguous nucleotides derived from a nucleotide sequence selected from the group consisting of SEQ ID NOs: 1 , 3, 5, 7, 9, and 11 , and the complement of such nucleotide sequences; and amplifying a nucleic acid fragment (preferably a cDNA inserted in a cloning vector) using the oligonucleotide primer.
- the amplified nucleic acid fragment preferably will encode a portion of a UDP glucose pyrophosphorylase polypeptide.
- Synthetic peptides representing portions of the instant amino acid sequences may be synthesized. These peptides can be used to immunize animals to produce polyclonal or monoclonal antibodies with specificity for peptides or proteins comprising the amino acid sequences. These antibodies can be then be used to screen cDNA expression libraries to isolate full-length cDNA clones of interest (Lerner (1984) Adv. Immunol. 36: 1 -34; Maniatis).
- the nucleic acid fragments of the instant invention may be used to create transgenic plants in which the disclosed polypeptides are present at higher or lower levels than normal or in cell types or developmental stages in which they are not normally found. This would have the effect of altering the level of cell wall and starch biosynthesis in those cells.
- Modulation of the expression of UDP-glucose pyrophosphorylase can be used to control carbohydrate partitioning between cell wall and starch biosynthesis. Suppression of this enzyme, for example, would be expected to shift carbon flux from the cell wall pathways using UDPG toward starch biosynthesis using G-l-P.
- Overexpression of the proteins of the instant invention may be accomplished by first constructing a chimeric gene in which the coding region is operably linked to a promoter capable of directing expression of a gene in the desired tissues at the desired stage of development.
- the chimeric gene may comprise promoter sequences and translation leader sequences derived from the same genes. 3' Non-coding sequences encoding transcription termination signals may also be provided.
- the instant chimeric gene may also comprise one or more introns in order to facilitate gene expression.
- Plasmid vectors comprising the isolated polynucleotide (or chimeric gene) may be constructed.
- the choice of plasmid vector is dependent upon the method that will be used to transform host plants. The skilled artisan is well aware of the genetic elements that must be present on the plasmid vector in order to successfully transform, select and propagate host cells containing the chimeric gene. The skilled artisan will also recognize that different independent transformation events will result in different levels and patterns of expression (Jones et al. (1985) EMBO J. 4:2411-2418; De Almeida et al. (1989) Mol. Gen. Genetics 275:78-86), and thus that multiple events must be screened in order to obtain lines displaying the desired expression level and pattern. Such screening may be accomplished by Southern analysis of DNA, Northern analysis of mRNA expression, Western analysis of protein expression, or phenotypic analysis.
- a chimeric gene designed for co-suppression of the instant polypeptide can be constructed by linking a gene or gene fragment encoding that polypeptide to plant promoter sequences.
- a chimeric gene designed to express antisense RNA for all or part of the instant nucleic acid fragment can be constructed by linking the gene or gene fragment in reverse orientation to plant promoter sequences. Either the co-suppression or antisense chimeric genes could be introduced into plants via transformation wherein expression of the corresponding endogenous genes are reduced or eliminated.
- tissue specific promoters may confer agronomic advantages relative to conventional mutations which may have an effect in all tissues in which a mutant gene is ordinarily expressed.
- tissue specific promoters may confer agronomic advantages relative to conventional mutations which may have an effect in all tissues in which a mutant gene is ordinarily expressed.
- special considerations are associated with the use of antisense or cosuppression technologies in order to reduce expression of particular genes.
- the proper level of expression of sense or antisense genes may require the use of different chimeric genes utilizing different regulatory elements known to the skilled artisan.
- the nature of these screens will generally be chosen on practical grounds. For example, one can screen by looking for changes in gene expression by using antibodies specific for the protein encoded by the gene being suppressed, or one could establish assays that specifically measure enzyme activity. A preferred method will be one which allows large numbers of samples to be processed rapidly, since it will be expected that a large number of transformants will be negative for the desired phenotype.
- the instant polypeptide (or portions thereof) may be produced in heterologous host cells, particularly in the cells of microbial hosts, and can be used to prepare antibodies to the these proteins by methods well known to those skilled in the art. The antibodies are useful for detecting the polypeptide of the instant invention in situ in cells or in vitro in cell extracts.
- Preferred heterologous host cells for production of the instant polypeptide are microbial hosts.
- Microbial expression systems and expression vectors containing regulatory sequences that direct high level expression of foreign proteins are well known to those skilled in the art. Any of these could be used to construct a chimeric gene for production of the instant polypeptide. This chimeric gene could then be introduced into appropriate microorganisms via transformation to provide high level expression of the encoded UDP glucose pyrophosphorylase.
- An example of a vector for high level expression of the instant polypeptide in a bacterial host is provided (Example 6).
- nucleic acid fragments of the instant invention may also be used as probes for genetically and physically mapping the genes that they are a part of, and as markers for traits linked to those genes. Such information may be useful in plant breeding in order to develop lines with desired phenotypes.
- the instant nucleic acid fragments may be used as restriction fragment length polymorphism (RFLP) markers.
- RFLP restriction fragment length polymorphism
- Southern blots (Maniatis) of restriction-digested plant genomic DNA may be probed with the nucleic acid fragments of the instant invention. The resulting banding patterns may then be subjected to genetic analyses using computer programs such as MapMaker (Lander et al. (1987) Genomics 7:174-181) in order to construct a genetic map.
- nucleic acid fragments of the instant invention may be used to probe Southern blots containing restriction endonuclease-treated genomic DNAs of a set of individuals representing parent and progeny of a defined genetic cross. Segregation of the DNA polymorphisms is noted and used to calculate the position of the instant nucleic acid sequence in the genetic map previously obtained using this population (Botstein et al. (1980) Am. J. Hum. Genet. 32:314-331).
- nucleic acid probes derived from the instant nucleic acid sequences may be used in direct fluorescence in situ hybridization (FISH) mapping (Trask (1991) Trends Genet. 7:149-154).
- FISH direct fluorescence in situ hybridization
- current methods of FISH mapping favor use of large clones (several to several hundred KB; see Laan et al. (1995) Genome Res. 5:13-20)
- improvements in sensitivity may allow performance of FISH mapping using shorter probes.
- a variety of nucleic acid amplification-based methods of genetic and physical mapping may be carried out using the instant nucleic acid sequences. Examples include allele-specific amplification (Kazazian (1989) J. Lab. Clin. Med.
- Loss of function mutant phenotypes may be identified for the instant cDNA clones either by targeted gene disruption protocols or by identifying specific mutants for these genes contained in a maize population carrying mutations in all possible genes (Ballinger and Benzer (1989) Proc. Natl. Acad. Sci USA 55:9402-9406; Koes et al. (1995) Proc. Natl. Acad. Sci USA 92:8149-8153; Bensen et al. (1995) Plant Cell 7:75-84). The latter approach may be accomplished in two ways.
- short segments of the instant nucleic acid fragments may be used in polymerase chain reaction protocols in conjunction with a mutation tag sequence primer on DNAs prepared from a population of plants in which Mutator transposons or some other mutation-causing DNA element has been introduced (see Bensen, supra).
- the amplification of a specific DNA fragment with these primers indicates the insertion of the mutation tag element in or near the plant gene encoding the instant polypeptide.
- the instant nucleic acid fragment may be used as a hybridization probe against PCR amplification products generated from the mutation population using the mutation tag sequence primer in conjunction with an arbitrary genomic site primer, such as that for a restriction enzyme site-anchored synthetic adaptor.
- an arbitrary genomic site primer such as that for a restriction enzyme site-anchored synthetic adaptor.
- EXAMPLE 1 Composition of cDNA Libraries: Isolation and Sequencing of cDNA Clones cDNA libraries representing mRNAs from various corn, rice, soybean, and wheat tissues were prepared. The characteristics of the libraries are described below.
- cDNA libraries may be prepared by any one of many methods available.
- the cDNAs may be introduced into plasmid vectors by first preparing the cDNA libraries in Uni-ZAPTM XR vectors according to the manufacturer's protocol (Stratagene Cloning Systems, La Jolla, CA). The Uni-ZAPTM XR libraries are converted into plasmid libraries according to the protocol provided by Stratagene. Upon conversion, cDNA inserts will be contained in the plasmid vector pBluescript.
- the cDNAs may be introduced directly into precut Bluescript II SK(+) vectors (Stratagene) using T4 DNA ligase (New England Biolabs), followed by transfection into DH10B cells according to the manufacturer's protocol (GIBCO BRL Products).
- T4 DNA ligase New England Biolabs
- plasmid DNAs are prepared from randomly picked bacterial colonies containing recombinant pBluescript plasmids, or the insert cDNA sequences are amplified via polymerase chain reaction using primers specific for vector sequences flanking the inserted cDNA sequences.
- Amplified insert DNAs or plasmid DNAs are sequenced in dye-primer sequencing reactions to generate partial cDNA sequences (expressed sequence tags or "ESTs"; see Adams et al., (1991) Science 252:1651-1656). The resulting ESTs are analyzed using a Perkin Elmer Model 377 fluorescent sequencer.
- EST sequences of the entire cDNA inserts comprising the indicated cDNA clones
- FIS cDNA clones
- Contig contigs assembled from two or more ESTs
- the sequence of the entire cDNA insert in clones sdp3c.pk013.121 and wleln.pk0063.d7 was determined and further searching of the DuPont proprietary database allowed the identification of a rice clone encoding UDP glucose pyrophosphorylase.
- the BLAST search using the sequences from clones listed in Table 4 revealed similarity of the polypeptides encoded by the cDNAs to UDP glucose pyrophosphorylase from Hordeum vulgare and Pyrus pyrifolia (NCBI General Identifier Nos. 6136111 and 6136112, respectively).
- the amino acid sequence of the Hordeum vulgare UDP glucose pyrophosphorylase found in NCBI General Identifier No.
- 6136111 is 100% identical to the amino acid sequence of the Hordeum vulgare UDP glucose pyrophosphorylase found in NCBI General Identifier No. 2117937. Shown in Table 4 are the BLAST results for individual ESTs ("EST”), or the sequences of the entire cDNA inserts comprising the indicated cDNA clones and encoding the entire protein (“CGS”):
- Figure 1 presents an alignment of the amino acid sequences set forth in SEQ ID NOs:2, 10, and 12 and the Hordeum vulgare sequence (SEQ ID NO:13).
- the data in Table 5 represents a calculation of the percent identity of the amino acid sequences set forth in SEQ ID NOs:2, 4 6, 8, 10, and 12 and the Hordeum vulgare sequence (SEQ ID NO:13).
- a chimeric gene comprising a cDNA encoding the instant polypeptide in sense orientation with respect to the maize 27 kD zein promoter that is located 5' to the cDNA fragment, and the 10 kD zein 3' end that is located 3' to the cDNA fragment, can be constructed.
- the cDNA fragment of this gene may be generated by polymerase chain reaction (PCR) of the cDNA clone using appropriate oligonucleotide primers. Cloning sites (Ncol or Smal) can be incorporated into the oligonucleotides to provide proper orientation of the DNA fragment when inserted into the digested vector pML103 as described below.
- Plasmid pML 103 has been deposited under the terms of the Budapest Treaty at ATCC (American Type Culture Collection, 10801 University Boulevard., Manassas, VA 20110-2209), and bears accession number ATCC 97366.
- the DNA segment from pML103 contains a 1.05 kb Sall-Ncol promoter fragment of the maize 27 kD zein gene and a 0.96 kb Smal-Sall fragment from the 3' end of the maize 10 kD zein gene in the vector pGem9Zf(+) (Promega).
- Vector and insert DNA can be ligated at 15°C overnight, essentially as described (Maniatis). The ligated DNA may then be used to transform E. coli XLl-Blue ( ⁇ picurian Coli XL-1 BlueTM; Stratagene).
- Bacterial transformants can be screened by restriction enzyme digestion of plasmid DNA and limited nucleotide sequence analysis using the dideoxy chain termination method (SequenaseTM DNA Sequencing Kit; U.S. Biochemical).
- the resulting plasmid construct would comprise a chimeric gene encoding, in the 5' to 3' direction, the maize 27 kD zein promoter, a cDNA fragment encoding the instant polypeptide, and the 10 kD zein 3' region.
- the chimeric gene described above can then be introduced into corn cells by the following procedure. Immature corn embryos can be dissected from developing caryopses derived from crosses of the inbred corn lines H99 and LH132. The embryos are isolated 10 to 11 days after pollination when they are 1.0 to 1.5 mm long. The embryos are then placed with the axis-side facing down and in contact with agarose-solidified N6 medium (Chu et al. (1975) Sci. Sin. Peking 18:659-668). The embryos are kept in the dark at 27°C.
- Friable embryogenic callus consisting of undifferentiated masses of cells with somatic proembryoids and embryoids borne on suspensor structures proliferates from the scutellum of these immature embryos.
- the embryogenic callus isolated from the primary explant can be cultured on N6 medium and sub-cultured on this medium every 2 to 3 weeks.
- the plasmid, p35S/Ac (obtained from Dr. Peter ⁇ ckes, Hoechst Ag, Frankfurt, Germany) may be used in transformation experiments in order to provide for a selectable marker.
- This plasmid contains the Pat gene (see European Patent Publication 0 242 236) which encodes phosphinothricin acetyl transf erase (PAT).
- PAT phosphinothricin acetyl transf erase
- the enzyme PAT confers resistance to herbicidal glutamine synthetase inhibitors such as phosphinothricin.
- the pat gene in p35S/Ac is under the control of the 35S promoter from Cauliflower Mosaic Virus (Odell et al.
- the particle bombardment method (Klein et al. (1987) Nature 327:70-73) may be used to transfer genes to the callus culture cells.
- gold particles (1 ⁇ m in diameter) are coated with DNA using the following technique.
- Ten ⁇ g of plasmid DNAs are added to 50 ⁇ L of a suspension of gold particles (60 mg per mL).
- Calcium chloride 50 ⁇ L of a 2.5 M solution
- spermidine free base (20 ⁇ L of a 1.0 M solution) are added to the particles.
- the suspension is vortexed during the addition of these solutions. After 10 minutes, the tubes are briefly centrifuged (5 sec at 15,000 rpm) and the supernatant removed. The particles are resuspended in 200 ⁇ L of absolute ethanol, centrifuged again and the supernatant removed. The ethanol rinse is performed again and the particles resuspended in a final volume of 30 ⁇ L of ethanol. An aliquot (5 ⁇ L) of the DNA-coated gold particles can be placed in the center of a KaptonTM flying disc (Bio-Rad Labs).
- the particles are then accelerated into the corn tissue with a BiolisticTM PDS-1000/He (Bio-Rad Instruments, Hercules CA), using a helium pressure of 1000 psi, a gap distance of 0.5 cm and a flying distance of 1.0 cm.
- BiolisticTM PDS-1000/He Bio-Rad Instruments, Hercules CA
- the embryogenic tissue is placed on filter paper over agarose- solidified N6 medium.
- the tissue is arranged as a thin lawn and covered a circular area of about 5 cm in diameter.
- the petri dish containing the tissue can be placed in the chamber of the PDS-1000/He approximately 8 cm from the stopping screen.
- the air in the chamber is then evacuated to a vacuum of 28 inches of Hg.
- the macrocarrier is accelerated with a helium shock wave using a rupture membrane that bursts when the He pressure in the shock tube reaches 1000 psi.
- tissue can be transferred to N6 medium that contains gluphosinate (2 mg per liter) and lacks casein or proline. The tissue continues to grow slowly on this medium. After an additional 2 weeks the tissue can be transferred to fresh N6 medium containing gluphosinate. After 6 weeks, areas of about 1 cm in diameter of actively growing callus can be identified on some of the plates containing the glufosinate- supplemented medium. These calli may continue to grow when sub-cultured on the selective medium. Plants can be regenerated from the transgenic callus by first transferring clusters of tissue to N6 medium supplemented with 0.2 mg per liter of 2,4-D. After two weeks the tissue can be transferred to regeneration medium (Fromm et al. (1990) Bio/Technology 5:833-839).
- a seed-specific expression cassette composed of the promoter and transcription terminator from the gene encoding the ⁇ subunit of the seed storage protein phaseolin from the bean Phaseolus vulgaris (Doyle et al. (1986) J Biol. Chem. 261 :9228-9238) can be used for expression of the instant polypeptide in transformed soybean.
- the phaseolin cassette includes about 500 nucleotides upstream (5') from the translation initiation codon and about 1650 nucleotides downstream (3') from the translation stop codon of phaseolin. Between the 5' and 3' regions are the unique restriction endonuclease sites Nco I (which includes the ATG translation initiation codon), Sma I, Kpn I and Xba I. The entire cassette is flanked by Hind III sites.
- the cDNA fragment of this gene may be generated by polymerase chain reaction
- PCR PCR of the cDNA clone using appropriate oligonucleotide primers. Cloning sites can be incorporated into the oligonucleotides to provide proper orientation of the DNA fragment when inserted into the expression vector. Amplification is then performed as described above, and the isolated fragment is inserted into a pUC18 vector carrying the seed expression cassette.
- Soybean embryos may then be transformed with the expression vector comprising sequences encoding the instant polypeptide.
- somatic embryos cotyledons, 3-5 mm in length dissected from surface sterilized, immature seeds of the soybean cultivar A2872, can be cultured in the light or dark at 26°C on an appropriate agar medium for 6-10 weeks. Somatic embryos which produce secondary embryos are then excised and placed into a suitable liquid medium. After repeated selection for clusters of somatic embryos which multiplied as early, globular staged embryos, the suspensions are maintained as described below.
- Soybean embryogenic suspension cultures can maintained in 35 mL liquid media on a rotary shaker, 150 rpm, at 26°C with florescent lights on a 16:8 hour day/night schedule. Cultures are subcultured every two weeks by inoculating approximately 35 mg of tissue into 35 mL of liquid medium. Soybean embryogenic suspension cultures may then be transformed by the method of particle gun bombardment (Klein et al. (1987) Nature (London) 327:70-73, U.S. Patent No. 4,945,050). A DuPont BiolisticTM PDS1000/HE instrument (helium retrofit) can be used for these transformations.
- a selectable marker gene which can be used to facilitate soybean transformation is a chimeric gene composed of the 35S promoter from Cauliflower Mosaic Virus (Odell et al. (1985) Nature 373:810-812), the hygromycin phosphotransferase gene from plasmid pJR225 (from E. coli; Gritz et al.(1983) Gene 25:179-188) and the 3' region of the nopaline synthase gene from the T-DNA of the Ti plasmid of Agrobacterium tumefaciens.
- the seed expression cassette comprising the phaseolin 5' region, the fragment encoding the instant polypeptide and the phaseolin 3' region can be isolated as a restriction fragment. This fragment can then be inserted into a unique restriction site of the vector carrying the marker gene.
- Approximately 300-400 mg of a two-week-old suspension culture is placed in an empty 60x15 mm petri dish and the residual liquid removed from the tissue with a pipette.
- approximately 5-10 plates of tissue are normally bombarded.
- Membrane rupture pressure is set at 1100 psi and the chamber is evacuated to a vacuum of 28 inches mercury.
- the tissue is placed approximately 3.5 inches away from the retaining screen and bombarded three times. Following bombardment, the tissue can be divided in half and placed back into liquid and cultured as described above.
- the liquid media may be exchanged with fresh media, and eleven to twelve days post bombardment with fresh media containing 50 mg/mL hygromycin. This selective media can be refreshed weekly.
- green, transformed tissue may be observed growing from untransformed, necrotic embryogenic clusters. Isolated green tissue is removed and inoculated into individual flasks to generate new, clonally propagated, transformed embryogenic suspension cultures. Each new line may be treated as an independent transformation event. These suspensions can then be subcultured and maintained as clusters of immature embryos or regenerated into whole plants by maturation and germination of individual somatic embryos.
- EXAMPLE 6 Expression of Chimeric Genes in Microbial Cells
- the cDNAs encoding the instant polypeptide can be inserted into the T7 E. coli expression vector pBT430.
- This vector is a derivative of pET-3a (Rosenberg et al. (1987) Gene 56:125-135) which employs the bacteriophage T7 RNA polymerase/T7 promoter system.
- Plasmid pBT430 was constructed by first destroying the EcoR I and Hind III sites in pET-3a at their original positions. An oligonucleotide adaptor containing EcoR I and Hind III sites was inserted at the BamH I site of pET-3a.
- Plasmid DNA containing a cDNA may be appropriately digested to release a nucleic acid fragment encoding the protein. This fragment may then be purified on a 1% NuSieve GTGTM low melting agarose gel (FMC). Buffer and agarose contain 10 ⁇ g/ml ethidium bromide for visualization of the DNA fragment. The fragment can then be purified from the agarose gel by digestion with GELaseTM (Epicentre Technologies) according to the manufacturer's instructions, ethanol precipitated, dried and resuspended in 20 ⁇ L of water. Appropriate oligonucleotide adapters may be ligated to the fragment using T4 DNA ligase (New England Biolabs, Beverly, MA).
- the fragment containing the ligated adapters can be purified from the excess adapters using low melting agarose as described above.
- the vector pBT430 is digested, dephosphorylated with alkaline phosphatase (NEB) and deproteinized with phenol/chloroform as described above.
- the prepared vector pBT430 and fragment can then be ligated at 16°C for 15 hours followed by transformation into DH5 electrocompetent cells (GIBCO BRL).
- Transformants can be selected on agar plates containing LB media and 100 ⁇ g/mL ampicillin. Transformants containing the gene encoding the instant polypeptide are then screened for the correct orientation with respect to the T7 promoter by restriction enzyme analysis.
- a plasmid clone with the cDNA insert in the correct orientation relative to the T7 promoter can be transformed into E. coli strain BL21(D ⁇ 3) (Studier et al. (1986) J. Mol. Biol. 189:113-130). Cultures are grown in LB medium containing ampicillin (100 mg/L) at 25°C. At an optical density at 600 nm of approximately 1, IPTG (isopropylthio- ⁇ -galactoside, the inducer) can be added to a final concentration of 0.4 mM and incubation can be continued for 3 h at 25°.
- IPTG isopropylthio- ⁇ -galactoside, the inducer
- Cells are then harvested by centrifugation and re-suspended in 50 ⁇ L of 50 mM Tris-HCl at pH 8.0 containing 0.1 mM DTT and 0.2 mM phenyl methylsulfonyl fluoride.
- a small amount of 1 mm glass beads can be added and the mixture sonicated 3 times for about 5 seconds each time with a microprobe sonicator.
- the mixture is centrifuged and the protein concentration of the supernatant determined.
- One ⁇ g of protein from the soluble fraction of the culture can be separated by SDS -poly aery lamide gel electrophoresis. Gels can be observed for protein bands migrating at the expected molecular weight.
- EXAMPLE 7 Functional Expression of the Soybean UDP-Galactose 4-Epimerase in Soybean Somatic Embryos
- the ability to change the levels of the raffinosaccharide pathway by overexpressing the gene from soybean clone sls2c.pk017.k22:fis in soybean somatic embryos was tested by preparing transgenic soybean somatic embryos and assaying the raffinose, stachyose, and sucrose levels.
- a cosuppressed phenotype should have low to nondetectable levels of raffinose and stachyose and increased levels of sucrose and can be expressed as a ratio of sucrose/(raffmose + stachyose).
- a ratio of less than 1 is considered a wild type phenotype, while a ratio of greater than 2.0 is considered a cosuppressed event.
- the entire insert from clone sls2c.pk017.k22:fis was amplified in a standard PCR reaction on a Perkin Elmer Applied Biosystems GeneAmp PCR System using Pfu polymerase (Stratagene).
- the resulting fragment is bound by an Nco I site at the 5' end and by a Pst I fragment at the 3' end.
- This fragment was digested, isolated, and ligated into the Nco I/Pst I sites of plasmid pKS 18HH (described in US Patent No. 5,846,784) which had been modified by the insertion of the soybean glycinin subunit Gl promoter and terminator signals at the Sac I site.
- the sequence of the soybean Gyl glycinin subunit Gl was published by Sims and Goldberg (1989, Nucl. Acids Res. 17:4386).
- the promoter sequence consists of nucleotides 1 through 690 and the terminator sequence consists of nucleotides 3126 through 3527.
- the new plasmid was named Gl-epimerase and contains the Gyl promoter, the epimerase sequence, and the Gyl termination signal surrounded by Sac I sites in plasmid pKS18HH. Transformation of Soybean Somatic Embryo Cultures
- Murashige & Skoog salt mixture my ⁇ -inositol 100.0 60 g maltose nicotinic acid 1.0 1 mL
- B5 vitamin stock pyridoxine HC1 1.0 7 g agarose tWamine 10.0 pH 5.7 *(Gibco BRL)
- Soybean embryonic suspension cultures were maintained in 35 mL liquid media (SB55) on a rotary shaker (150 rpm) at 28°C with a mix of fluorescent and incandescent lights providing a 16 h day 8 h night cycle. Cultures were subcultured every 2 to 3 weeks by inoculating approximately 35 mg of tissue into 35 mL of fresh liquid media.
- Soybean embryonic suspension cultures were transformed with Gl-epimerase by the method of particle gun bombardment (see Klein et al. (1987) Nature 327:70-73) using a DuPont Biolistic PDSIOOO/He instrument.
- Five ⁇ L of Gl-epimerase plasmid DNA (1 g/L), 50 ⁇ L CaCl (2.5 M), and 20 ⁇ L spermidine (0.1 M) were added to 50 ⁇ L of a 60 mg/mL 1 mm gold particle suspension.
- the particle preparation was agitated for 3 minutes, spun in a microfuge for 10 seconds and the supernate removed.
- the DNA-coated particles were then washed once with 400 ⁇ L of 70% ⁇ ethanol and resuspended in 40 ⁇ L of anhydrous ethanol.
- the DNA/particle suspension was sonicated three times for 1 second each.
- Five ⁇ L of the DNA-coated gold particles were then loaded on each macro carrier disk.
- Approximately 300 to 400 mg of two-week-old suspension culture was placed in an empty 60 mm X 15 mm petri dish and the residual liquid removed from the tissue using a pipette.
- the tissue was placed about 3.5 inches away from the retaining screen and bombarded twice.
- Membrane rupture pressure was set at 1100 psi and the chamber was evacuated to -28 inches of Hg. Two plates were bombarded , and following bombardment, the tissue was divided in half, placed back into liquid media, and cultured as described above.
- Transformed embryonic clusters were removed from liquid culture media and placed on a solid agar media, SB103, containing 0.5%) charcoal to begin maturation. After 1 week, embryos were transferred to SB 103 media minus charcoal. After 5 weeks on SB 103 media, maturing embryos were separated and placed onto SB 148 media. During maturation embryos were kept at 26°C with a mix of fluorescent and incandescent lights providing a 16 h day 8 h night cycle. To mimic seed dry down, embryos were harvested after 5 weeks on SB 148 media. Each embryonic cluster gave rise to 5 to 20 somatic embryos.
- Non-transformed somatic embryos were cultured by the same method as used for the transformed somatic embryos. Analysis of Transformed Somatic Embryos
- somatic embryos were harvested from 14 independently transformed lines.
- Soluble carbohydrates were extracted by crushing the embryos with a nylon pestle in a microfuge tube containing 200 ⁇ L of 80% methanol. Extraction was repeated with an additional 200 ⁇ L of 80% methanol and the supernatants combined and dried.
- the soluble carbohydrates were resuspended in 200 ⁇ L water and analyzed using a Dionex DX500 chromatography system. Carbohydrates were separated on a Dionex CarboPac PAI (4x250 mm) column using 95% 0.2 M NaOH, 5% water at 1.0 ml/min. A total of 14 events (10 embryos each) were analyzed.
- a cosuppressed phenotype should have low to nondetectable levels of raffinose and stachyose and increased levels of sucrose and can be expressed as a ratio of sucrose/(raffinose + stachyose).
- a ratio of less than 1.0 is considered a wildtype phenotype, while a ratio of greater than 2.0 is considered a cosuppressed event.
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- 2000-02-09 WO PCT/US2000/003453 patent/WO2000047755A2/en not_active Application Discontinuation
- 2000-02-09 CA CA2716429A patent/CA2716429A1/en not_active Abandoned
- 2000-02-09 CA CA2359811A patent/CA2359811C/en not_active Expired - Fee Related
- 2000-02-09 CA CA2359803A patent/CA2359803C/en not_active Expired - Fee Related
- 2000-02-10 AR ARP000100587 patent/AR022567A1/es not_active Application Discontinuation
Non-Patent Citations (1)
Title |
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See references of WO0047748A3 * |
Also Published As
Publication number | Publication date |
---|---|
WO2000047755A2 (en) | 2000-08-17 |
CA2716429A1 (en) | 2000-08-17 |
CA2359811A1 (en) | 2000-08-17 |
EP1151115A2 (de) | 2001-11-07 |
AU3228300A (en) | 2000-08-29 |
CA2359803C (en) | 2013-04-09 |
WO2000047755A3 (en) | 2001-03-08 |
CA2359803A1 (en) | 2000-08-17 |
CA2359811C (en) | 2010-12-21 |
AU3227300A (en) | 2000-08-29 |
AR022567A1 (es) | 2002-09-04 |
WO2000047748A2 (en) | 2000-08-17 |
WO2000047748A3 (en) | 2000-12-14 |
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