6nfw | pdb_00006nfw
Potyvirus viral protein genome linked (VPg) emulates the m7G cap to recruit the eukaryotic translation initiation factor eIF4E
Structural highlights
FunctionPOLG_PVYN Required for aphid transmission and also has proteolytic activity. Only cleaves a Gly-Gly dipeptide at its own C-terminus. Interacts with virions and aphid stylets. Acts as a suppressor of RNA-mediated gene silencing, also known as post-transcriptional gene silencing (PTGS), a mechanism of plant viral defense that limits the accumulation of viral RNAs. May have RNA-binding activity.[UniProtKB:P04517] Has helicase activity. It may be involved in replication. Indispensable for virus replication.[UniProtKB:P13529] Indispensable for virus replication.[UniProtKB:P09814] Mediates the cap-independent, EIF4E-dependent translation of viral genomic RNAs (PubMed:31712417). Binds to the cap-binding site of host EIF4E and thus interferes with the host EIF4E-dependent mRNA export and translation (PubMed:31712417). VPg-RNA directly binds EIF4E and is a template for transcription (PubMed:31712417). Also forms trimeric complexes with EIF4E-EIF4G, which are templates for translation (PubMed:31712417).[1] Has RNA-binding and proteolytic activities.[UniProtKB:P04517] An RNA-dependent RNA polymerase that plays an essential role in the virus replication. Involved in aphid transmission, cell-to-cell and systemis movement, encapsidation of the viral RNA and in the regulation of viral RNA amplification.[UniProtKB:P04517] Publication Abstract from PubMedViruses have transformed our understanding of mammalian RNA processing, including facilitating the discovery of the methyl-7-guanosine (m(7)G) cap on the 5' end of RNAs. The m(7)G 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 m(7)G 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 m(7)G 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. Structural studies of the eIF4E-VPg complex reveal a direct competition for capped RNA: Implications for translation.,Coutinho de Oliveira L, Volpon L, Rahardjo AK, Osborne MJ, Culjkovic-Kraljacic B, Trahan C, Oeffinger M, Kwok BH, Borden KLB Proc Natl Acad Sci U S A. 2019 Nov 11. pii: 1904752116. doi:, 10.1073/pnas.1904752116. PMID:31712417[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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