In its tRNA acceptor end binding domain, the glutamyl-tRNA synthetase (GluRS) of Escherichia colicontains one atom ofzinc that holds the extremities ofa segment (Cys98-x-Cys100-x24-Cys125-x-His127) homologous to the Escherichia coliglutaminyl-tRNA synthetase (GlnRS) loop where a leucine residue stabilizes the peeled-back conformation of tRNA Gln acceptor end. We report here that the GluRS zinc-binding region belongs to the novel SWIM domain family characterized by the signature C-x-C-xn-C-x-H (n¼6–25),.
