Chemistry: molecular biology and microbiology – Process of mutation – cell fusion – or genetic modification – Introduction of a polynucleotide molecule into or...
Reexamination Certificate
1999-07-01
2002-01-15
Prouty, Rebecca E. (Department: 1652)
Chemistry: molecular biology and microbiology
Process of mutation, cell fusion, or genetic modification
Introduction of a polynucleotide molecule into or...
C435S476000, C435S252300, C435S320100, C435S006120, C435S194000, C536S023200
Reexamination Certificate
active
06338966
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 sulfate assimilation proteins in plants and seeds.
BACKGROUND OF THE INVENTION
Sulfate assimilation is the process by which environmental sulfur is fixed into organic sulfur for use in cellular metabolism. The two major end products of this process are the essential amino acids cysteine and methionine. These amino acids are limiting in food and feed; they cannot be synthesized by animals and thus must be acquired from plant sources. Increasing the level of these amino acids in feed products is thus of major economic value. Key to that process is increasing the level of organic sulfur available for cysteine and methionine biosynthesis.
Multiple enzymes are involved in sulfur assimilation. These include: High affinity sulfate transporter and low affinity sulfate transporter proteins which serve to transport sulfur from the outside environment across the cell membrane into the cell (Smith et al. (1995)
PNAS
92(20):9373-9377). Once sulfur is in the cell sulfate adenylyltransferase (ATP sulfurylase; Bolchia et al. (1999)
Plant Mol. Biol.
39(3):527-537) catalyzes the first step in assimilation, converting the inorganic sulfur into an organic form, adenosine-5′ phosphosulfate (APS). Next, several enzymes further modify organic sulfur for use in the biosynthesis of cysteine and methionine. For example, adenylylsulfate kinase (APS kinase), catalyzes the conversion of APS to the biosynthetic intermediate PAPS (3′-phospho-adenosine-5′ phosphosulfate; Arz et al. (1994)
Biochim. Biophy. Acta
1218(3):447-452). APS reductase (5′ adenylyl phosphosulphate reductase) is utilized in an altemative pathway, resulting in an inorganic but cellularly bound (bound to a carrier), form of sulfur (sulfite; Setya et al. (1996)
PNAS
93(23):13383-13388). Sulfite reductase firther reduces the sulfite, still attached to the carrier, to sulfide and serine O-acetyltransferase converts serine to O-acetylserine, which will serve as the backbone to which the sulfide will be transferred to from the carrier to form cysteine (Yonelcura-Sakalibara et al. (1998)
J. Biolchem.
124(3):615-621 and Saito et al. (1995)
J. Biol. Chem.
270(27):16321-16326).
As described, each of these enzymes is involved in sulfate assimilation and the pathway leading to cysteine biosynthesis, which in turn serves as an organic sulfur donor for multiple other pathways in the cell, including methionine biosynthesis. Together or singly these enzymes and the genes that encode them have utility in overcoming the sulfur limitations known to exist in crop plants. It may be possible to modulate the level of sulfur containing compounds in the cell, including the nutritionally critical amino acids cysteine and methionine. Specifically, their overexpression using tissue specific promoters will remove the enzyme in question as a possible limiting step, thus increasing the potential flux through the pathway to the essential amino acids. This will allow the engineering of plant tissues with increases levels of these amino acids, which now often must be added a supplements to animal feed.
The sequence of a corn ATP sulfurylase became available to the public after the instant invention was made (see Bolchi, A. et al. (1999)
Plant Mol. Biol.
39 (3):527-537; NCBI Identifier No. gi 2738750).
SUMMARY OF THE INVENTION
The instant invention relates to isolated nucleic acid fragments encoding sulfate assimilation proteins. Specifically, this invention concerns an isolated nucleic acid fragment encoding an ATP sulfurylase (sulfate adenyltransferase) and an isolated nucleic acid fragment that is substantially similar to an isolated nucleic acid fragment encoding an ATP sulfurylase. In addition, this invention relates to a nucleic acid fragment that is complementary to the nucleic acid fragment encoding ATP sulfurylase. An additional embodiment of the instant invention pertains to a polypeptide encoding all or a substantial portion of an ATP sulfurylase.
In another embodiment, the instant invention relates to a chimeric gene encoding an ATP sulfurylase, or to a chimeric gene that comprises a nucleic acid fragment that is complementary to a nucleic acid fragment encoding an ATP sulfurylase, 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 ATP sulfurylase, 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 ATP sulfurylase in a transformed host cell comprising: a) transforming a host cell with a chimeric gene comprising a nucleic acid fragment encoding an ATP sulfurylase; 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 ATP sulfurylase 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 ATP sulfurylase.
REFERENCES:
Klonus et al., Plant J., 6(1), 105-112, Jun. 1994.*
Carmen Rotte et al., Plant Physiology, vol. 124:715-724, 10/2000, Differential Subcellular Localization and Expression of ATP Sulfurylase and 5′-Adenylylsulfate Reductase During Ontogenesis of Arabidopsis Leaves Indicates That Cytosolic and Plastid Forms of ATP Sulfurylase May Have Specialized Functions.
Smith et al., (1995) PNAS U.S.A. 92(20):9373-9377.
Bolchi et al. (1999) Plant Mol. Biol. 39(3):527-537.
Arz et al. (1994) Biochim. Biophy. Acta 1218(3):447-452.
Setya et al. (1996) PNAS U.S.A. 93(23):13383-13388.
Saito et al. (1995) J. Biol. Chem. 270(27):16321-16326.
NCBI General Identifier No. g2738750, Mar. 31, 1999.
NCBI General Identifier No. g479090, Aug. 22, 1994.
Plant J. 6(1), pp. 105-112 (1994).
NCBI General Identifier No. g629733, Apr. 12, 1996.
NCBI General Identifier No. g629562, Mar. 15, 1996.
Keiko Yonekura-Sakakibara et al., (1998) J. Biochem. 124, 615-621.
Sasaki T., EMBL Database, Aug. 6, 1997,Rice CDNA from callus, XP00212812.
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Bork C. et al., “Isolation and characterization of a gene for assimilatory sulfite reductase fromArabidopsis thaliana” Gene: An International Journal On Genes And Genomes, vol. 212, No. 1, May 28, 1998, XP004122435.
Bruhl A. et al., “A CDNA clone fromArabidopsis thalianaencoding plastidic ferredixon: sulfite reductase” Biochimica et Biophysica Acta, vol. 1295, 1996, pp. 119-124, XP002121813.
Database WPI, Section Ch, Week 199440, Derwent Publications Ltd., London, GB; p. 6, An 1994-321282, XP002121814.
Smith F. et al., Plant J., vol. 12, No. 4, 1997, pp. 875-884, XP002129909.
Sohlberg L. and Sussex I., EMBL Database,Jul. 1997, XP002129910.
Federspiel N. et al., EMBL Database, Jun. 1998 XP00212911.
Minobe Y. and Sasaki, T., EMBL Database, XP002129912, Nov. 1993.
Bolchi A. et al., EMBL Database, Jan. 8, 1998 XP002121790.
Ng et al., sulfate transporter fromSporobulus stapfianus, EMBL Database, Mar. 1997, XP002121791.
Takahashi et al., Regulation of sulfur assimilation in highe
Allen Stephen M.
Anderson Shawn L.
Falco Saverio Carl
Rafalski J. Antoni
E. I. du Pont de Nemours & Company
Monshipouri Maryann
Prouty Rebecca E.
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