Primary Citation of Related Structures: 6GZ3, 6GZ4, 6GZ5
PubMed Abstract:
Translocation moves the tRNA 2 ⋅mRNA module directionally through the ribosome during the elongation phase of protein synthesis. Although translocation is known to entail large conformational changes within both the ribosome and tRNA substrates, the orchestrated events that ensure the speed and fidelity of this critical aspect of the protein synthesis mechanism have not been fully elucidated. Here, we present three high-resolution structures of intermediates of translocation on the mammalian ribosome where, in contrast to bacteria, ribosomal complexes containing the translocase eEF2 and the complete tRNA 2 ⋅mRNA module are trapped by the non-hydrolyzable GTP analog GMPPNP. Consistent with the observed structures, single-molecule imaging revealed that GTP hydrolysis principally facilitates rate-limiting, final steps of translocation, which are required for factor dissociation and which are differentially regulated in bacterial and mammalian systems by the rates of deacyl-tRNA dissociation from the E site.
Organizational Affiliation:
Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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