CP1 domain in Escherichia coli leucyl-tRNA synthetase is crucial for its editing function

Jian Feng Chen, Ni Ni Guo, Tong Li, En Duo Wang, Ying Lai Wang

Research output: Contribution to journalArticle

Abstract

The amino acid discrimination by aminoacyl-tRNA synthetase is achieved through two sifting steps; amino acids larger than the cognate substrate are rejected by a 'coarse sieve', while the reaction products of amino acids smaller than the cognate substrate will go through a 'fine sieve' and be hydrolyzed. This 'double-sieve' mechanism has been proposed for IleRS, a class I aminoacyl-tRNA synthetase. In this study, we created LeuRS-B, a mutant leucyl-tRNA synthetase from Escherichia coli with a duplication of the peptide fragment from Met328 to Pro368 (within its CP1 domain). This mutant has 50% of the leucylation activity of the wild-type enzyme and has the same ability to discriminate noncognate amino acids in the first step of the reaction. However, LeuRS-B can catalyze mischarging of tRNA(Leu) by methionine or isoleucine, suggesting that it is impaired in the ability to edit incorrect products. Wild-type leucyl-tRNA synthetase can edit the mischarged tRNA(Leu) made by LeuRS-B, while a separated CP1 domain cannot. These data suggest that the CP1 domain of leucyl-tRNA synthetase is crucial to the second editing sieve and that CP1 needs the structural context in leucyl-tRNA synthetase to fulfill its editing function.

Original languageEnglish (US)
Pages (from-to)6726-6731
Number of pages6
JournalBiochemistry
Volume39
Issue number22
DOIs
StatePublished - Jun 6 2000
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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