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Proc Natl Acad Sci U S A. 2019 Nov 26;116(48):24056-24065. doi: 10.1073/pnas.1904752116. Epub 2019 Nov 11.

Structural studies of the eIF4E-VPg complex reveal a direct competition for capped RNA: Implications for translation.

Author information

1
Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada.
2
Department for Systems Biology, Institut de Recherches Cliniques de Montréal, Montréal, QC H2W 1R7, Canada.
3
Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3T 1J4, Canada.
4
Division of Experimental Medicine, McGill University, Montréal, QC H3A 1A3, Canada.
5
Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada; katherine.borden@umontreal.ca.

Abstract

Viruses have transformed our understanding of mammalian RNA processing, including facilitating the discovery of the methyl-7-guanosine (m7G) cap on the 5' end of RNAs. The m7G cap is required for RNAs to bind the eukaryotic translation initiation factor eIF4E and associate with the translation machinery across plant and animal kingdoms. The potyvirus-derived viral genome-linked protein (VPg) is covalently bound to the 5' end of viral genomic RNA (gRNA) and associates with host eIF4E for successful infection. Divergent models to explain these observations proposed either an unknown mode of eIF4E engagement or a competition of VPg for the m7G cap-binding site. To dissect these possibilities, we resolved the structure of VPg, revealing a previously unknown 3-dimensional (3D) fold, and characterized the VPg-eIF4E complex using NMR and biophysical techniques. VPg directly bound the cap-binding site of eIF4E and competed for m7G cap analog binding. In human cells, VPg inhibited eIF4E-dependent RNA export, translation, and oncogenic transformation. Moreover, VPg formed trimeric complexes with eIF4E-eIF4G, eIF4E bound VPg-luciferase RNA conjugates, and these VPg-RNA conjugates were templates for translation. Informatic analyses revealed structural similarities between VPg and the human kinesin EG5. Consistently, EG5 directly bound eIF4E in a similar manner to VPg, demonstrating that this form of engagement is relevant beyond potyviruses. In all, we revealed an unprecedented modality for control and engagement of eIF4E and show that VPg-RNA conjugates functionally engage eIF4E. As such, potyvirus VPg provides a unique model system to interrogate eIF4E.

KEYWORDS:

VPg; eIF4E; m7 cap; potyvirus; translation

PMID:
31712417
PMCID:
PMC6883836
[Available on 2020-05-11]
DOI:
10.1073/pnas.1904752116

Conflict of interest statement

The authors declare no competing interest.

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