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Publication Abstract from PubMed

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 ~20 A. An additional 4-A 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.

Time-resolved cryo-EM visualizes ribosomal translocation with EF-G and GTP.,Carbone CE, Loveland AB, Gamper HB Jr, Hou YM, Demo G, Korostelev AA Nat Commun. 2021 Dec 13;12(1):7236. doi: 10.1038/s41467-021-27415-0. PMID:34903725^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.