EMD-1554

Single-particle
13.0 Å
EMD-1554 Deposition: 08/09/2008
Map released: 05/05/2009
Last modified: 24/10/2012
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-1554

Pretranslocation ribosome. Group after ML3D classification. Non-racheted and classical tRNA positions.

EMD-1554

Single-particle
13.0 Å
EMD-1554 Deposition: 08/09/2008
Map released: 05/05/2009
Last modified: 24/10/2012
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Escherichia coli
Sample: 70 mRNA tRNAfMet fMetLeu-tRNALeu

Deposition Authors: Julian P, Konevega AL , Scheres SHW, Lazaro M , Gil D , Wintermeyer W, Rodnina MV , Valle M
Structure of ratcheted ribosomes with tRNAs in hybrid states.
Julian P, Konevega AL , Scheres SH , Lazaro M , Gil D , Wintermeyer W, Rodnina MV , Valle M
(2008) PNAS , 105 , 16924 - 16927
Abstract:
During protein synthesis, tRNAs and mRNA move through the ribosome between aminoacyl (A), peptidyl (P), and exit (E) sites of the ribosome in a process called translocation. Translocation is accompanied by the displacement of the tRNAs on the large ribosomal subunit toward the hybrid A/P and P/E states and by a rotational movement (ratchet) of the ribosomal subunits relative to one another. So far, the structure of the ratcheted state has been observed only when translation factors were bound to the ribosome. Using cryo-electron microscopy and classification, we show here that ribosomes can spontaneously adopt a ratcheted conformation with tRNAs in their hybrid states. The peptidyl-tRNA molecule in the A/P state, which is visualized here, is not distorted compared with the A/A state except for slight adjustments of its acceptor end, suggesting that the displacement of the A-site tRNA on the 50S subunit is passive and is induced by the 30S subunit rotation. Simultaneous subunit ratchet and formation of the tRNA hybrid states precede and may promote the subsequent rapid and coordinated tRNA translocation on the 30S subunit catalyzed by elongation factor G.