ROLE OF ZINC IN TRANSFER-RNA-ACCEPTOR STEM BINDING BY GLUTAMYL-TRANSFER-RNA SYNTHETASE FROM ESCHERICHIA-COLI - A MOLECULAR MODELING STUDY

A model of the N-terminal half of glutamyl-tRNA synthetase from E. coi l was constructed on the basis of similarity in sequence and function of GlutaminyI- and GIutamyl-tRNA synthetases. The glutaminyl-tRNA synt hetase does not contain any zinc atom, but glutamyl-tRNA synthetase fr om 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 th at the zinc atom is well outside the contact region of the acceptor st em of tRNA. The placement of a zinc atom at a significant distance fro m the tRNA acceptor stem indicates that the role of zinc is likely to be indirect and structural.