Interaction of EF-Tu with EF-Ts:: substitution of his-118 in EF-Tu destabilizes the EF-Tu•EF-Ts complex but does not prevent EF-Ts from stimulating the release of EF-Tu-bound GDP

Elongation factor Tu from Escherichia coli with His118 substituted by glycine (EF-TuH118G) was found to be defective in complex formation with EF-Ts. EF-Ts in excess failed to dissociate kirromycin from the EF-TuH118G kirromycin complex and to form a stable complex with EF-TuH118G on column chromatography. However, the stimulatory effect of EF-Ts on GDP dissociation from EF-TuH118G GDP and on poly(U)-directed poly(Phe) synthesis catalyzed by EF-TuH118G was only partially influenced. These results indicate that His118, while very important for the formation of a stable EF-Tu EF-Ts complex, is not essential for the transmission of the EF-Ts-dependent signal accelerating the release of the EF-Tu-bound GDP. (C) 1998 Federation of European Biochemical Societies.