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Structures of tmRNA and SmpB as they transit through the ribosome

Abstract : In bacteria, trans-translation is the main rescue system, freeing ribosomes stalled on defective messenger RNAs. This mechanism is driven by small protein B (SmpB) and transfer-messenger RNA (tmRNA), a hybrid RNA known to have both a tRNA-like and an mRNA-like domain. Here we present four cryo-EM structures of the ribosome during trans-translation at resolutions from 3.0 to 3.4 Å. These include the high-resolution structure of the whole pre-accommodated state, as well as structures of the accommodated state, the translocated state, and a translocation intermediate. Together, they shed light on the movements of the tmRNA-SmpB complex in the ribosome, from its delivery by the elongation factor EF-Tu to its passage through the ribosomal A and P sites after the opening of the B1 bridges. Additionally, we describe the interactions between the tmRNA-SmpB complex and the ribosome. These explain why the process does not interfere with canonical translation.
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Contributor : Laurent Jonchère Connect in order to contact the contributor
Submitted on : Tuesday, September 14, 2021 - 9:53:10 AM
Last modification on : Monday, October 11, 2021 - 3:50:25 PM



Charlotte Guyomar, Gaetano D’urso, Sophie Chat, Emmanuel Giudice, Reynald Gillet. Structures of tmRNA and SmpB as they transit through the ribosome. Nature Communications, Nature Publishing Group, 2021, 12 (1), pp.4909. ⟨10.1038/s41467-021-24881-4⟩. ⟨hal-03343248⟩



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