Restoring Species-specific Posttransfer Editing Activity to a Synthetase with a Defunct Editing Domain.
From: Department of Biochemistry, University of Minnesota, Minneapolis, MN 55455, USA.
Proceedings of the National Academy of Sciences of the United States of America
- Publish Date: Feb 2007
- ISSN: 0027-8424
- Volume: 104
- Issue: 7
- Pages: 2127-32
- Medium: Print
- Language: English
- Citation (JAMA): SternJohn Julius, Hati Sanchita, Siliciano Paul G, et al. Restoring Species-specific Posttransfer Editing Activity to a Synthetase with a Defunct Editing Domain.. Proc. Natl. Acad. Sci. U.S.A. Feb 2007;104:2127-32
Abstract
Aminoacyl-tRNA synthetases are multidomain proteins responsible for the attachment of specific amino acids to their tRNA substrates. Prolyl-tRNA synthetases (ProRSs) are notable due to their particularly diverse architectures through evolution. For example, Saccharomyces cerevisiae ProRS possesses an N-terminal extension with weak homology to a bacterial-specific domain typically present as an insertion (INS) within the aminoacylation active site. The INS domain has been shown to contain a “posttransfer” editing active site responsible for cleaving the aminoacyl-ester bond of misacylated Ala-tRNA(Pro) species. However, wild-type S. cerevisiae ProRS does not perform posttransfer editing in vitro. Here, we show that replacement of the N-terminal domain of S. cerevisiae ProRS with the Escherichia coli INS domain confers posttransfer editing function to this chimeric enzyme, with specificity for yeast Ala-tRNA(Pro). In contrast, the isolated INS domain displays only weak editing activity and lacks tRNA sequence specificity. These results emphasize the modular nature of synthetase editing active sites and demonstrate how in evolution, a weak editing activity can be converted to a more robust state through fusion to the body of a synthetase. In this manner, a single editing module can be distributed to different synthetases, and simultaneously acquire specificity and enhanced activity.
Mesh Headings (Keywords): Amino Acyl-tRNA Synthetases, Binding Sites, Proline, Protein Biosynthesis, RNA Editing, RNA, Transfer, Amino Acyl, Saccharomyces cerevisiae Proteins, Species Specificity, Substrate Specificity
Check for Full Text / PubMed Unique Identifier (PMID): 17283340
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