Peske, FrankFrankPeskeMatassova, Natalia B.Natalia B.MatassovaSavelsbergh, AndreasAndreasSavelsberghRodnina, MarinaMarinaRodninaWintermeyer, WolfgangWolfgangWintermeyer2017-09-072017-09-072000https://resolver.sub.uni-goettingen.de/purl?gro-2/1983Elongation factor G (EF-G) from Escherichia coli is a large, five-domain GTPase that promotes tRNA translocation on the ribosome. Full activity requires GTP hydrolysis, suggesting that a conformational change of the factor is important for function. To restrict the intramolecular mobility, two cysteine residues were engineered into domains 1 and 5 of EF-G that spontaneously formed a disulfide cross-link. Cross-linked EF-G retained GTPase activity on the ribosome, whereas it was inactive in translocation as well as in turnover. Both activities were restored when the cross-link was reversed by reduction. These results strongly argue against a GTPase switch-type model of EF-G function and demonstrate that conformational mobility is an absolute requirement for EF-G function on the ribosome.journal_article10.1016/S1097-2765(00)00049-6109839960000891661000273144367