Time-resolved cryo-EM visualizes ribosomal translocation with EF-G and GTP

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Authors	CARBONE C.E. LOVELAND A.B. GAMPER H.B. HOU Y.M. DEMO Gabriel KOROSTELEV A.A.
Year of publication	2021
Type	Article in Periodical
Magazine / Source	Nature Communications
MU Faculty or unit	Central European Institute of Technology
Citation
Web	https://www.nature.com/articles/s41467-021-27415-0
Doi	http://dx.doi.org/10.1038/s41467-021-27415-0
Keywords	ELONGATION-FACTOR-GTRANSFER-RNA TRANSLOCATIONCONFORMATIONAL-CHANGESINTERSUBUNIT MOVEMENTINTERMEDIATE STATESCRYSTAL-STRUCTURESTRUCTURAL BASISHYBRID STATE80S RIBOSOMEHYDROLYSIS
Description	During translation, a conserved GTPase elongation factor-EF-G in bacteria or eEF2 in eukaryotes-translocates tRNA and mRNA through the ribosome. EF-G has been proposed to act as a flexible motor that propels tRNA and mRNA movement, as a rigid pawl that biases unidirectional translocation resulting from ribosome rearrangements, or by various combinations of motor- and pawl-like mechanisms. Using time-resolved cryo-EM, we visualized GTP-catalyzed translocation without inhibitors, capturing elusive structures of ribosome.EF-G intermediates at near-atomic resolution. Prior to translocation, EF-G binds near peptidyl-tRNA, while the rotated 30S subunit stabilizes the EF-G GTPase center. Reverse 30S rotation releases Pi and translocates peptidyl-tRNA and EF-G by similar to 20 angstrom. An additional 4-angstrom translocation initiates EF-G dissociation from a transient ribosome state with highly swiveled 30S head. The structures visualize how nearly rigid EF-G rectifies inherent and spontaneous ribosomal dynamics into tRNA-mRNA translocation, whereas GTP hydrolysis and Pi release drive EF-G dissociation.
Related projects:	Simultaneous gene transcription and translation Crosstalk between transcription and translation