Histidine‐118 of elongation factor Tu: its role in aminoacyl‐tRNA binding and regulation of the GTPase activity

Abstract
The function of His118 in elongation factor (EF)‐Tu from Escherichia coli was investigated by its substitution with glycine. The substitution had a differential effect on individual functions of the protein. The affinity for aminoacyl (aa)‐tRNA and the intrinsic GTPase activity of the mutant EF‐Tu were decreased whereas the response of its GTPase center to aa‐tRNA was strongly increased. These results suggest that the region around His118 is involved in the binding of aa‐tRNA and in the transmission of a turn‐off signal generated by the interaction with aa‐tRNA and directed to the GTPase center of EF‐Tu.