4C4Q

Cryo-EM map of the CSFV IRES in complex with the small ribosomal 40S subunit and DHX29


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 8.50 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 2.1 of the entry. See complete history


Literature

Hepatitis-C-Virus-Like Internal Ribosome Entry Sites Displace Eif3 to Gain Access to the 40S Subunit

Hashem, Y.Desgeorges, A.Dhote, V.Langlois, R.Liao, H.Y.Grassucci, R.A.Pestova, T.V.Hellen, C.U.T.Frank, J.

(2013) Nature 503: 539

  • DOI: https://doi.org/10.1038/nature12658
  • Primary Citation of Related Structures:  
    4C4Q

  • PubMed Abstract: 

    Hepatitis C virus (HCV) and classical swine fever virus (CSFV) messenger RNAs contain related (HCV-like) internal ribosome entry sites (IRESs) that promote 5'-end independent initiation of translation, requiring only a subset of the eukaryotic initiation factors (eIFs) needed for canonical initiation on cellular mRNAs. Initiation on HCV-like IRESs relies on their specific interaction with the 40S subunit, which places the initiation codon into the P site, where it directly base-pairs with eIF2-bound initiator methionyl transfer RNA to form a 48S initiation complex. However, all HCV-like IRESs also specifically interact with eIF3 (refs 2, 5-7, 9-12), but the role of this interaction in IRES-mediated initiation has remained unknown. During canonical initiation, eIF3 binds to the 40S subunit as a component of the 43S pre-initiation complex, and comparison of the ribosomal positions of eIF3 and the HCV IRES revealed that they overlap, so that their rearrangement would be required for formation of ribosomal complexes containing both components. Here we present a cryo-electron microscopy reconstruction of a 40S ribosomal complex containing eIF3 and the CSFV IRES. Remarkably, although the position and interactions of the CSFV IRES with the 40S subunit in this complex are similar to those of the HCV IRES in the 40S-IRES binary complex, eIF3 is completely displaced from its ribosomal position in the 43S complex, and instead interacts through its ribosome-binding surface exclusively with the apical region of domain III of the IRES. Our results suggest a role for the specific interaction of HCV-like IRESs with eIF3 in preventing ribosomal association of eIF3, which could serve two purposes: relieving the competition between the IRES and eIF3 for a common binding site on the 40S subunit, and reducing formation of 43S complexes, thereby favouring translation of viral mRNAs.


  • Organizational Affiliation

    1] Howard Hughes Medical Institute (HHMI), Department of Biochemistry and Molecular Biophysics, Columbia University, New York City, New York 10032, USA [2] Department of Biochemistry and Molecular Biophysics, Columbia University, New York City, New York 10032, USA.


Macromolecules
Find similar nucleic acids by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains LengthOrganismImage
INTERNAL RIBOSOMAL ENTRY SITEA [auth N]233Classical swine fever virus
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 8.50 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 
EM Software:
TaskSoftware PackageVersion
RECONSTRUCTIONRELION
RECONSTRUCTIONSPIDER

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-10-30
    Type: Initial release
  • Version 1.1: 2013-11-13
    Changes: Database references
  • Version 1.2: 2013-12-04
    Changes: Database references
  • Version 2.0: 2017-08-02
    Changes: Atomic model, Data collection, Derived calculations
  • Version 2.1: 2024-05-08
    Changes: Data collection, Database references, Refinement description