Chemistry: molecular biology and microbiology – Plant cell or cell line – per se ; composition thereof;... – Plant cell or cell line – per se – contains exogenous or...
Reexamination Certificate
1999-07-02
2001-02-06
Bui, Phuong T. (Department: 1638)
Chemistry: molecular biology and microbiology
Plant cell or cell line, per se ; composition thereof;...
Plant cell or cell line, per se, contains exogenous or...
C435S006120, C435S183000, C435S193000, C435S410000, C435S419000, C435S252300, C435S320100, C530S350000, C530S370000, C536S023100, C536S023600, C536S024100, C800S278000
Reexamination Certificate
active
06184036
ABSTRACT:
FIELD OF THE INVENTION
This invention is in the field of plant molecular biology. More specifically, this invention pertains to nucleic acid fragments encoding ornithine biosynthetic enzymes in plants and seeds.
BACKGROUND OF THE INVENTION
Ornithine is converted into arginine in the urea cycle. Intermediaries in the ornithine biosynthesis pathway are important in other steps of this cycle. Amino acid N-acetyl transferase (EC 2.3.1.1) catalyzes the first reaction in a pathway that leads to the synthesis of ornithine from L-glutamate giving N-acetylglutamate as its intermediary product. Amino acid N-acetyl transferase is also known as N-acetylglutamate synthetase (AGS) and is encoded by the argA locus in bacteria. No plant N-acetylglutamate has been described to date.
Carbamoyl phosphate synthase I, the mitochondrial enzyme that catalyzes the first committed step of the urea cycle, is allosterically activated by N-acetyl glutamate. The rate of urea production by the liver is, in fact, correlated with the N-acetylglutamate concentration. Increased urea synthesis is required when amino acid breakdown rates increase, generating excess nitrogen that must be extracted. Increase in these breakdown rates are signaled by an increase in glutamate concentration through transamination reaction. This situation, in turn, causes an increase in N-acetylglutamate synthesis, stimulating carbamoyl phosphate synthetase and the entire urea cycle.
Ornithine oxo-acid transaminase (EC 2.6.1.13), also called omithine aminotransferase, catalyzes the conversion of omithine to L-glutamate semialdehyde. The gene encoding ornithine oxo-acid transaminase has been cloned from
Aspergillus nidulans, Saccharomyces cerevisiae, Plasmodiumfalciparum, Vigna aconitifolia
, rat, mouse and man. No plant sequences encoding omithine oxo-acid transaminase have been described to date.
SUMMARY OF THE INVENTION
The instant invention relates to isolated nucleic acid fragments encoding ornithine-oxo-acid transaminase. Specifically, this invention concerns an isolated nucleic acid fragment encoding an ornithine-oxo-acid transaminase and an isolated nucleic acid fragment that is substantially similar to an isolated nucleic acid fragment encoding an omithine-oxo-acid transaminase. In addition, this invention relates to a nucleic acid fragment that is complementary to the nucleic acid fragment encoding omithine-oxo-acid transaminase.
An additional embodiment of the instant invention pertains to a polypeptide encoding all or a substantial portion of an omithine-oxo-acid transaminase.
In another embodiment, the instant invention relates to a chimeric gene encoding an ornithine-oxo-acid transaminase, or to a chimeric gene that comprises a nucleic acid fragment that is complementary to a nucleic acid fragment encoding an ornithine-oxo-acid transaminase, operably linked to suitable regulatory sequences, wherein expression of the chimeric gene results in production of levels of the encoded protein in a transformed host cell that is altered (i.e., increased or decreased) from the level produced in an untransformed host cell.
In a further embodiment, the instant invention concerns a transformed host cell comprising in its genome a chimeric gene encoding an ornithine-oxo-acid transaminase, operably linked to suitable regulatory sequences. Expression of the chimeric gene results in production of altered levels of the encoded protein in the transformed host cell. The transformed host cell can be of eukaryotic or prokaryotic origin, and include cells derived from higher plants and microorganisms. The invention also includes transformed plants that arise from transformed host cells of higher plants, and seeds derived from such transformed plants.
An additional embodiment of the instant invention concerns a method of altering the level of expression of an ornithine-oxo-acid transaminase in a transformed host cell comprising: a) transforming a host cell with a chimeric gene comprising a nucleic acid fragment encoding an ornithine-oxo-acid transaminase; and b) growing the transformed host cell under conditions that are suitable for expression of the chimeric gene wherein expression of the chimeric gene results in production of altered levels of ornithine-oxo-acid transaminase in the transformed host cell.
An addition embodiment of the instant invention concerns a method for obtaining a nucleic acid fragment encoding all or a substantial portion of an amino acid sequence encoding an ornithine-oxo-acid transaminase.
BRIEF DESCRIPTION OF THE SEQUENCE LISTINGS
The invention can be more fully understood from the following detailed description and the accompanying Sequence Listing which form a part of this application.
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 polypeptide, 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
Ornithine-Oxo-Acid Transaminase
SEQ ID NO:
Plant
Clone Designation
(Nucleotide)
(Amino Acid)
Corn
Contig of:
1
2
cen3n.pk0204.g9
p0015.cdped57r
p0128.cpibt92r
Rice
r10n.pk119.k7
3
4
Rice
Contig of:
5
6
rds1c.pk002.m1
rl0n.pk0003.b1
rlr2.pk0015.a2
rlr2.pk0033.f4
Soybean
sgs4c.pk005.o1
7
8
Wheat
Contig of:
9
10
wlk1.pk0024.b2
wre1n.pk0004.b7
The Sequence Listing contains the one letter code for nucleotide sequence characters and the three letter codes for amino acids as defined in conformity with the IUPAC-IUBMB standards described in
Nucleic Acids Research
13:3021-3030 (1985) and in the
Biochemical Journal
219 (No. 2):345-373 (1984) which are herein incorporated by reference. The symbols and format used for nucleotide and amino acid sequence data comply with the rules set forth in 37 C.F.R. §1.822.
DETAILED DESCRIPTION OF THE INVENTION
In the context of this disclosure, a number of terms shall be utilized. As used herein, a “nucleic acid fragment” is a polymer of RNA or DNA that is single- or double-stranded, optionally containing synthetic, non-natural or altered nucleotide bases. A nucleic acid fragment in the form of a polymer of DNA may be comprised of one or more segments of cDNA, genomic DNA or synthetic DNA.
As used herein, “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.
As used herein, “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-à-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 sp
Cahoon Rebecca E.
Falco Saverio Carl
Rafalski J. Antoni
Bui Phuong T.
E. I. Du Pont de Nemours and Company
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