Plant aminoacyl-tRNA synthetase

Details Plant aminoacyl-tRNA synthetase Plant aminoacyl-tRNA synthetase

1999-07-14

2001-07-03

Achutamurthy, Ponnathapu (Department: 1652)

Chemistry: molecular biology and microbiology

Enzyme , proenzyme; compositions thereof; process for...

C435S320100, C435S325000, C435S254110, C435S252300, C435S419000, C536S023100, C536S023200, C800S278000, C800S285000, C800S286000, C800S295000

Reexamination Certificate

active

06255090

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 aminoacyl-tRNA synthetase in plants and seeds.
BACKGROUND OF THE INVENTION
All tRNAs have two functions: to chemically link to a specific amino acid and to recognize a codon in mRNA so that the linked amino acid can be added to a growing peptide chain during protein synthesis. In general there is at least one aminoacyl-tRNA synthetase for each of the twenty amino acids. A specific aminoacyl-tRNA synthetase links an amino acid to the 2′ or 3′ hydroxyl of the adenosine residue at the 3′-terminus of a tRNA molecule. Once its correct amino acid is attached, a tRNA then recognizes a codon in mRNA, thus deliverng its amino acid to the growing polypeptide chain. These enzymatic functions are critical to gene expression (Neidhart et al. (1975)
Annu. Rev. Microbiol.
29:215-250). Mutations in tRNA synthetases often result in alterations in protein synthesis and in some cases cell death.
Plants like other cellular organisms have aminoacyl-tRNA synthetases. However a complete description of the plant ‘complement’ of aminoacyl-tRNA synthetases has not been published. It is anticipated that plants will likely have at least forty aminoacyl-tRNA synthetases. Plants have three sites of protein synthesis: the cytoplasm, the mitochondria and the chloroplast. Accordingly, there could be as many as sixty aminoacyl-tRNA synthetases. Based on knowledge of other eukaryotes the cytoplasmic and mitochondrial aminoacyl-tRNA synthetases are expected to be encoded by the same gene. This gene should be nuclearly encoded and produce two alternate products, one with a mitochondrial specific transit peptide, and the other without this targeting signal. The chloroplast is the other site of protein synthesis in plants. Based on a few examples of known plant chloroplast specific aminoacyl-tRNA synthetase genes it appears that these genes are also nuclear-encoded. Chloroplast aminoacyl-tRNA synthetases are directed to the chloroplast by a transit peptide.
Because of the central role aminoacyl-tRNA synthetases play in protein synthesis any agent that inhibits or disrupts aminoacyl-tRNA synthetase activity is likely to be toxic. Indeed a number of aminoacyl-tRNA synthetase inhibitors (antibiotics and herbicides) are known (Zon et al. (1988)
Phytochemishy
27(3):711-714 and Heacock et al. (1996)
Bioorganic Chemistry
24(3):273-289). Thus it may be possible to develop new herbicides that target arinoacyl-tRNA synthetases and engineer aminoacyl-tRNA synthetases that are resistant to such herbicides. Accordingly, the availability of nucleic acid sequences encoding all or a portion of these enzymes would facilitate studies to better understand protein synthesis in plants, provide genetic tools for the manipulation of gene expression, and provide a possible target for herbicides.
SUMMARY OF THE INVENTION
The instant invention relates to isolated nucleic acid fragments encoding aminoacyl-tRNA synthetase. Specifically, this invention concerns an isolated nucleic acid fragment encoding an aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase and an isolated nucleic acid fragment that is substantially similar to an isolated nucleic acid fragment encoding an aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase. In addition, this invention relates to a nucleic acid fragment that is complementary to the nucleic acid fragment encoding aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase.
An additional embodiment of the instant invention pertains to a polypeptide encoding all or a substantial portion of an aminoacyl-tRNA synthetaseselected from the group consisting of aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase and tyrosyl-tRNA synthetase.
In another embodinent, the instant invention relates to a chimeric gene encoding an aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase, or to a chimeric gene that comprises a nucleic acid fragment that is complementary to a nucleic acid fragment encoding an aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase, 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 aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase, 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 aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase in a transformed host cell comprising: a) transforming a host cell with a chimeric gene comprising a nucleic acid fragment encoding an aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase; 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 aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase 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 aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase.
A further embodiment of the instant invention is a method for evaluating at least one compound for its ability to inhibit the activity of an aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase, the method comprising the steps of: (a) transforming a host cell with a chimeric gene comprising a nucleic acid fragment encoding an aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase, operably linked to suitable regulatory sequences; (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 aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase in the transformed host cell; (c) optionally purifing the aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase expressed by the transformed host cell; (d) treating the aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase with a compound to be tested; and (e) comparing the activity of the aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase that has been treated with a test compound to the activity of an untreated aspartyl-tRNA synthetase, cysteinyl-tRNA synthetase, tryptophanyl-tRNA synthetase or tyrosyl-tRNA synthetase, thereby selecting compounds with potential for inhibitory activity.
BRIEF

Affiliated with

Also associated with

Rating

Plant aminoacyl-tRNA synthetase does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Plant aminoacyl-tRNA synthetase, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plant aminoacyl-tRNA synthetase will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2564227