Restoring species-specific posttransfer editing activity to a synthetase with a defunct editing domain.
Proc Natl Acad Sci U S A
; 104(7): 2127-32, 2007 Feb 13.
Article
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| MEDLINE
| ID: mdl-17283340
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.
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Biosíntesis de Proteínas
/
Edición de ARN
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Aminoacil-ARNt Sintetasas
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2007
Tipo del documento:
Article
País de afiliación:
Estados Unidos