Initiation of translation by cricket paralysis virus IRES requires its translocation in the ribosome.
Bottom Line: By using recent advances in single-particle electron cryomicroscopy, we have solved the structure of CrPV-IRES bound to the ribosome of the yeast Kluyveromyces lactis in both the canonical and rotated states at overall resolutions of 3.7 and 3.8 Å, respectively.In both states, the pseudoknot PKI of the CrPV-IRES mimics a tRNA/mRNA interaction in the decoding center of the A site of the 40S ribosomal subunit.Translocation of the IRES by elongation factor 2 (eEF2) is required to bring the first codon of the mRNA into the A site and to allow the start of translation.
Affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.Show MeSH
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Mentions: The rotated state of the ribosome differs from the canonical state by a counterclockwise rotation of the small subunit, including an additional movement of the head, as well as a movement of the L1 stalk (Figure 2A). Because the CrPV-IRES maintains interactions with each subunit in both states, the rotation of the subunits results in a somewhat different orientation and conformation for the CrPV-IRES in the two states (Figure 2B).
Affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.