Crystal structure of E. synthetase and ligand revealed key residues coil arglnyl-tRNA binding studies in arginine recognition

The arginyl-tRNA synthetase （ArgRS） catalyzes the esterification reaction between L-arginine and its cog- nate tRNAArg. Previously reported structures of ArgRS shed considerable light on the tRNA recognition mech- anism, while the aspect of amino acid binding in ArgRS remains largely unexplored. Here we report the first crystal structure of E. coli ArgRS （eArgRS） complexed with L-arginine, and a series of mutational studies using isothermal titration calorimetry （ITC）. Combined with previously reported work on ArgRS, our results eluci- dated the structural and functional roles of a series of important residues in the active site, which furthered our understanding of this unique enzyme.