Retracing the evolution of amino acid specificity in glutaminyl‐tRNA synthetase

FEBS Letters

Söll, Dieter¹  Ibba, Michael¹  Hong, Kwang-Won¹ 

[1] Department of Molecular Biophysics and Biochemistry, Yale University, P.O. Box 208114, 266 Whitney Avenue, New Haven, CT 06520-8114, USA

关键词: Glutamic acid;    Glutamine;    Glutaminyl-tRNA synthetase;    tRNA;    Evolution;    Escherichia coli;   

DOI  :  10.1016/S0014-5793(98)00968-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Molecular phylogenetic studies of glutaminyl-tRNA synthetase suggest that it has relatively recently evolved from the closely related enzyme glutamyl-tRNA synthetase. We have now attempted to retrace one of the key steps in this process by selecting glutaminyl-tRNA synthetase mutants displaying enhanced glutamic acid recognition. Mutagenesis of two residues proximal to the active site, Phe-90 and Tyr-240, was found to improve glutamic acid recognition 3–5-fold in vitro and resulted in the misacylation of tRNA^Gln with glutamic acid. In vivo expression of the genes encoding these misacylating variants of glutaminyl-tRNA synthetase reduced cellular growth rates by 40%, probably as a result of an increase in translational error rates. These results provide the first biochemical evidence that glutaminyl-tRNA synthetase originated through duplication and consequent diversification of an ancestral glutamyl-tRNA synthetase-encoding gene.

【 授权许可】

Unknown