title: Synchronous tRNA movements during translocation on the ribosome are orchestrated by elongation factor G and GTP hydrolysis.
abstract: The translocation of tRNAs through the ribosome proceeds through numerous small steps in which tRNAs gradually shift their positions on the small and large ribosomal subunits. The most urgent questions are: (i) whether these intermediates are important; (ii) how the ribosomal translocase, the GTPase elongation factor G (EF-G), promotes directed movement; and (iii) how the energy of GTP hydrolysis is coupled to movement. In the light of recent advances in biophysical and structural studies, we argue that intermediate states of translocation are snapshots of dynamic fluctuations that guide the movement. In contrast to current models of stepwise translocation, kinetic evidence shows that the tRNAs move synchronously on the two ribosomal subunits in a rapid reaction orchestrated by EF-G and GTP hydrolysis. EF-G combines the energy regimes of a GTPase and a motor protein and facilitates tRNA movement by a combination of directed Brownian ratchet and power stroke mechanisms.
authors.affiliation: Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Wolf
authors.initials: W
authors.lastname: Holtkamp
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wintermeyer
authors.forename: Marina V
authors.initials: MV
authors.lastname: Rodnina
mesh_terms: D000818:Animals; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D009068:Movement; D020653:Peptide Elongation Factor G / Q000737:chemistry / Q000378:metabolism*; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D020653:Peptide Elongation Factor G; D006160:Guanosine Triphosphate; D012343:RNA, Transfer
keywords: GTP hydrolysis; hybrid tRNA states; ribosome; ribosome motions; thermal fluctuations; translation