Aminoacyl-tRNA Synthetase : Structural Basis for the Substrate Recognition and the Molecular Evolution

Abstract

Aminoacyl-tRNA synthetases (aaRS's) play key roles in the correct protein biosynthesis through strict recognition/ligation of the cognate amino acid and tRNA. Twenty aaRS's were evolutionally devided into two classes (class I and class II) based on the architecture of the ATP-binding domain. Our recent result on the crystal structure of class-I aaRS (glutamyl-tRNA synthetase) delineates that aaRS's accomplish their strict recognition of the tRNA through a combination of insertions and deletions of modular structures in the class/subclass-defining domains and a total exchange of the non-conserved anticodon-binding domains. In contrast, structure of ternary complex of aaRS ·ATP ·amino-acid suggests that the strict amino-acid recognition is accomplished through evolutionary accumulation of mutation of the amino acid residues in the amino-acid binding site.