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-Structure paper
Title | Spontaneous reverse movement of mRNA-bound tRNA through the ribosome. |
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Journal, issue, pages | Nat Struct Mol Biol, Vol. 14, Issue 4, Page 318-324, Year 2007 |
Publish date | Mar 18, 2007 |
Authors | Andrey L Konevega / Niels Fischer / Yuri P Semenkov / Holger Stark / Wolfgang Wintermeyer / Marina V Rodnina / |
PubMed Abstract | During the translocation step of protein synthesis, a complex of two transfer RNAs bound to messenger RNA (tRNA-mRNA) moves through the ribosome. The reaction is promoted by an elongation factor, ...During the translocation step of protein synthesis, a complex of two transfer RNAs bound to messenger RNA (tRNA-mRNA) moves through the ribosome. The reaction is promoted by an elongation factor, called EF-G in bacteria, which, powered by GTP hydrolysis, induces an open, unlocked conformation of the ribosome that allows for spontaneous tRNA-mRNA movement. Here we show that, in the absence of EF-G, there is spontaneous backward movement, or retrotranslocation, of two tRNAs bound to mRNA. Retrotranslocation is driven by the gain in affinity when a cognate E-site tRNA moves into the P site, which compensates the affinity loss accompanying the movement of peptidyl-tRNA from the P to the A site. These results lend support to the diffusion model of tRNA movement during translocation. In the cell, tRNA movement is biased in the forward direction by EF-G, which acts as a Brownian ratchet and prevents backward movement. |
External links | Nat Struct Mol Biol / PubMed:17369838 |
Methods | EM (single particle) |
Resolution | 12.0 - 16.0 Å |
Structure data | EMDB-1323: EMDB-1324: |
Source |
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