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- Title
Structure of the mammalian 80S initiation complex with initiation factor 5B on HCV-IRES RNA.
- Authors
Yamamoto, Hiroshi; Unbehaun, Anett; Loerke, Justus; Behrmann, Elmar; Collier, Marianne; Bürger, Jörg; Mielke, Thorsten; Spahn, Christian M T
- Abstract
The universally conserved eukaryotic initiation factor (eIF) 5B, a translational GTPase, is essential for canonical translation initiation. It is also required for initiation facilitated by the internal ribosomal entry site (IRES) of hepatitis C virus (HCV) RNA. eIF5B promotes joining of 60S ribosomal subunits to 40S ribosomal subunits bound by initiator tRNA (Met-tRNAiMet). However, the exact molecular mechanism by which eIF5B acts has not been established. Here we present cryo-EM reconstructions of the mammalian 80S-HCV-IRES-Met-tRNAiMet-eIF5B-GMPPNP complex. We obtained two substates distinguished by the rotational state of the ribosomal subunits and the configuration of initiator tRNA in the peptidyl (P) site. Accordingly, a combination of conformational changes in the 80S ribosome and in initiator tRNA facilitates binding of the Met-tRNAiMet to the 60S P site and redefines the role of eIF5B as a tRNA-reorientation factor.
- Subjects
MAMMALIAN cell cycle; HEPATITIS C virus; MOLECULAR structure of RNA; EUKARYOTIC cells; GTPASE-activating protein; RIBOSOMAL RNA; TRANSFERASES; ANGIOTENSIN converting enzyme
- Publication
Nature Structural & Molecular Biology, 2014, Vol 21, Issue 8, p721
- ISSN
1545-9993
- Publication type
Article
- DOI
10.1038/nsmb.2859