RRC ID 69941
Author Iwakawa HO, Tajima Y, Taniguchi T, Kaido M, Mise K, Tomari Y, Taniguchi H, Okuno T.
Title Poly(A)-binding protein facilitates translation of an uncapped/nonpolyadenylated viral RNA by binding to the 3' untranslated region.
Journal J Virol
Abstract Viruses employ an alternative translation mechanism to exploit cellular resources at the expense of host mRNAs and to allow preferential translation. Plant RNA viruses often lack both a 5' cap and a 3' poly(A) tail in their genomic RNAs. Instead, cap-independent translation enhancer elements (CITEs) located in the 3' untranslated region (UTR) mediate their translation. Although eukaryotic translation initiation factors (eIFs) or ribosomes have been shown to bind to the 3'CITEs, our knowledge is still limited for the mechanism, especially for cellular factors. Here, we searched for cellular factors that stimulate the 3'CITE-mediated translation of Red clover necrotic mosaic virus (RCNMV) RNA1 using RNA aptamer-based one-step affinity chromatography, followed by mass spectrometry analysis. We identified the poly(A)-binding protein (PABP) as one of the key players in the 3'CITE-mediated translation of RCNMV RNA1. We found that PABP binds to an A-rich sequence (ARS) in the viral 3' UTR. The ARS is conserved among dianthoviruses. Mutagenesis and a tethering assay revealed that the PABP-ARS interaction stimulates 3'CITE-mediated translation of RCNMV RNA1. We also found that both the ARS and 3'CITE are important for the recruitment of the plant eIF4F and eIFiso4F factors to the 3' UTR and of the 40S ribosomal subunit to the viral mRNA. Our results suggest that dianthoviruses have evolved the ARS and 3'CITE as substitutes for the 3' poly(A) tail and the 5' cap of eukaryotic mRNAs for the efficient recruitment of eIFs, PABP, and ribosomes to the uncapped/nonpolyadenylated viral mRNA.
Volume 86(15)
Pages 7836-49
Published 2012-8-1
DOI 10.1128/JVI.00538-12
PII JVI.00538-12
PMID 22593149
PMC PMC3421650
MeSH 3' Untranslated Regions / physiology* Cell-Free System / metabolism Eukaryotic Initiation Factor-4F / genetics Eukaryotic Initiation Factor-4F / metabolism Plant Proteins / genetics Plant Proteins / metabolism* Poly(A)-Binding Proteins / genetics Poly(A)-Binding Proteins / metabolism* Protein Binding Protein Biosynthesis / physiology* RNA, Viral / genetics RNA, Viral / metabolism* Ribosome Subunits, Small, Eukaryotic Tombusviridae / physiology* Triticum / metabolism
IF 4.501
Arabidopsis / Cultured plant cells, genes rpc00001