Cryo-EM of elongating ribosome with EF-Tu•GTP elucidates tRNA proofreading.

ABSTRACT: Ribosomes accurately decode mRNA by proofreading each aminoacyl-tRNA that is delivered by the elongation factor EF-Tu¹. To understand the molecular mechanism of this proofreading step it is necessary to visualize GTP-catalysed elongation, which has remained a challenge^2-4. Here we use time-resolved cryogenic electron microscopy to reveal 33 ribosomal states after the delivery of aminoacyl-tRNA by EF-Tu•GTP. Instead of locking cognate tRNA upon initial recognition, the ribosomal decoding centre dynamically monitors codon-anticodon interactions before and after GTP hydrolysis. GTP hydrolysis enables the GTPase domain of EF-Tu to extend away, releasing EF-Tu from tRNA. The 30S subunit then locks cognate tRNA in the decoding centre and rotates, enabling the tRNA to bypass

SUBMITTER: Loveland AB 

PROVIDER: S-EPMC7483604 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature