Ensemble cryo-EM uncovers inchworm-like translocation of a viral IRES through the ribosome
UMass Chan AffiliationsDepartment of Biochemistry and Molecular Pharmacology
RNA Therapeutics Institute
Taura syndrome virus
elongation factor eEF2
internal ribosome entry site
MetadataShow full item record
AbstractInternal ribosome entry sites (IRESs) mediate cap-independent translation of viral mRNAs. Using electron cryo-microscopy of a single specimen, we present five ribosome structures formed with the Taura syndrome virus IRES and translocase eEF2*GTP bound with sordarin. The structures suggest a trajectory of IRES translocation, required for translation initiation, and provide an unprecedented view of eEF2 dynamics. The IRES rearranges from extended to bent to extended conformations. This inchworm-like movement is coupled with ribosomal inter-subunit rotation and 40S head swivel. eEF2, attached to the 60S subunit, slides along the rotating 40S subunit to enter the A site. Its diphthamide-bearing tip at domain IV separates the tRNA-mRNA-like pseudoknot I (PKI) of the IRES from the decoding center. This unlocks 40S domains, facilitating head swivel and biasing IRES translocation via hitherto-elusive intermediates with PKI captured between the A and P sites. The structures suggest missing links in our understanding of tRNA translocation.
Elife. 2016 May 9;5. pii: e14874. doi: 10.7554/eLife.14874. Link to article on publisher's site
Permanent Link to this Itemhttp://hdl.handle.net/20.500.14038/40035
RightsCopyright © 2016, Abeyrathne et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
Except where otherwise noted, this item's license is described as Copyright © 2016, Abeyrathne et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.