Cryo-EM ensemble captures EF-G mediated ribosomal translocation in action

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Authors	DEMO Gabriel CARBONE Christine LOVELAND Anna SVIDRITSKIY Egor GAMPER Howard HOU Ya-Ming KOROSTELEV Andrei
Year of publication	2021
Type	Conference abstract
MU Faculty or unit	Central European Institute of Technology
Citation
Description	During protein synthesis, transfer RNAs (tRNAs) and messenger RNA (mRNA) codons are translocated within the ribosome from the A to P to E sites, respectively. Translocation of tRNAs anticodons and mRNA along the small ribosomal 30S subunit is catalyzed by a conserved GTPase, elongation factor G(EF-G) in bacteria. The structural mechanism how the ribosome and EF-G maintain the open reading frame has not been visualized because the rapid GTP hydrolysis step has prevented the capture of authentic EF-G bound structural intermediates. Here, we present our single particle cryo-EM study aimed at characterizing translocation without using EF-G mutations or antibiotics. We report newly described intermediate structural state, which visualized the transition of two tRNAs from the A and P to P and E sites during translocation. The structure visualizes how nearly rigid EF-G rectifies inherent and spontaneous ribosomal dynamics into tRNA and mRNA translocation. This work therefore uncovers a missing link in the understanding of the synchronous movement of tRNAs and mRNA during translation elongation.
Related projects:	Crosstalk between transcription and translation