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

Christine E Carbone, Anna B Loveland, Howard B Gamper, Ya-Ming Hou, Gabriel Demo, Andrei A Korostelev

Nature communications 2021 Dec 13

filter terms:

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 Å. An additional 4-Å 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. © 2021. The Author(s).

Citation

Christine E Carbone, Anna B Loveland, Howard B Gamper, Ya-Ming Hou, Gabriel Demo, Andrei A Korostelev. Time-resolved cryo-EM visualizes ribosomal translocation with EF-G and GTP. Nature communications. 2021 Dec 13;12(1):7236