Role of zinc in tRNA-acceptor stem binding by glutamyl-tRNA synthetase from E.coli: a molecular modeling study

A model of the N-terminal half of glutamyl-tRNA synthetase from E. coli was constructed on the basis of similarity in sequence and function of Glutaminyl- and Glutamyl-tRNA synthetases. The glutaminyl-tRNA synthetase does not contain any zinc atom, but glutamyl-tRNA synthetase from E. coli contains one atom of zinc. The specific role of zinc is not yet known. In this article, molecular modeling is employed to show that the zinc atom is well outside the contact region of the acceptor stem of tRNA. The placement of a zinc atom at a significant distance from the tRNA acceptor stem indicates that the role of zinc is likely to be indirect and structural.