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Title | Structure of the mammalian 80S initiation complex with initiation factor 5B on HCV-IRES RNA. |
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Journal, issue, pages | Nat Struct Mol Biol, Vol. 21, Issue 8, Page 721-727, Year 2014 |
Publish date | Jul 27, 2014 |
Authors | Hiroshi Yamamoto / Anett Unbehaun / Justus Loerke / Elmar Behrmann / Marianne Collier / Jörg Bürger / Thorsten Mielke / Christian M T Spahn / |
PubMed 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 ...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-tRNAi(Met)). 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-tRNAi(Met)-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-tRNAi(Met) to the 60S P site and redefines the role of eIF5B as a tRNA-reorientation factor. |
External links | Nat Struct Mol Biol / PubMed:25064512 |
Methods | EM (single particle) |
Resolution | 8.9 - 9.5 Å |
Structure data | |
Chemicals | ChemComp-GNP: ChemComp-MG: |
Source |
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Keywords | RIBOSOME / TRANSLATION INITIATION / HEPATITIS C VIRUS INTERNAL RIBOSOME ENTRY SITE / EUKARYOTIC INITIATION FACTOR 5B |