Conformational changes of elongation factor G on the ribosome during tRNA translocation.
Publication Type:Journal Article
Source:Cell, Volume 160, Issue 1-2, p.219-27 (2015)
Keywords:Depsipeptides, Escherichia coli, Models, Molecular, Peptide Elongation Factor G, Ribosomal Proteins, Ribosomes, RNA, Transfer, Thermus thermophilus, X-Ray Diffraction
<p>The universally conserved GTPase elongation factor G (EF-G) catalyzes the translocation of tRNA and mRNA on the ribosome after peptide bond formation. Despite numerous studies suggesting that EF-G undergoes extensive conformational rearrangements during translocation, high-resolution structures exist for essentially only one conformation of EF-G in complex with the ribosome. Here, we report four atomic-resolution crystal structures of EF-G bound to the ribosome programmed in the pre- and posttranslocational states and to the ribosome trapped by the antibiotic dityromycin. We observe a previously unseen conformation of EF-G in the pretranslocation complex, which is independently captured by dityromycin on the ribosome. Our structures provide insights into the conformational space that EF-G samples on the ribosome and reveal that tRNA translocation on the ribosome is facilitated by a structural transition of EF-G from a compact to an elongated conformation, which can be prevented by the antibiotic dityromycin. </p>