Publication Type:Journal Article
Source:J Biol Chem, Volume 284, Number 21, p.14189-202 (2009)
ISBN:0021-9258 (Print)<br/>0021-9258 (Linking)
Keywords:3' Untranslated Regions/genetics, 5' Untranslated Regions/genetics, Base Sequence, Eukaryotic Initiation Factor-4E/ metabolism, Eukaryotic Initiation Factor-4F/ metabolism, Frameshifting, Ribosomal, Kinetics, Molecular Sequence Data, Mutation/genetics, Nucleic Acid Conformation, Plant Viruses/ genetics, Protein Binding, Protein Biosynthesis, Protein Subunits/metabolism, Regulatory Sequences, Ribonucleic Acid/ genetics, RNA Caps/ chemistry/genetics, RNA, Viral/chemistry/genetics, Solutions, Triticum/ metabolism
RNAs of many positive strand RNA viruses lack a 5' cap structure and instead rely on cap-independent translation elements (CITEs) to facilitate efficient translation initiation. The mechanisms by which these RNAs recruit ribosomes are poorly understood, and for many viruses the CITE is unknown. Here we identify the first CITE of an umbravirus in the 3'-untranslated region of pea enation mosaic virus RNA 2. Chemical and enzymatic probing of the approximately 100-nucleotide PEMV RNA 2 CITE (PTE), and mutagenesis revealed that it forms a long, bulged helix that branches into two short stem-loops, with a possible pseudoknot interaction between a C-rich bulge at the branch point and a G-rich bulge in the main helix. The PTE inhibited translation in trans, and addition of eIF4F, but not eIFiso4F, restored translation. Filter binding assays revealed that the PTE binds eIF4F and its eIF4E subunit with high affinity. Tight binding required an intact cap-binding pocket in eIF4E. Among many PTE mutants, there was a strong correlation between PTE-eIF4E binding affinity and ability to stimulate cap-independent translation. We conclude that the PTE recruits eIF4F by binding eIF4E. The PTE represents a different class of translation enhancer element, as defined by its structure and ability to bind eIF4E in the absence of an m(7)G cap.
Wang, Zhaohui<br/>Treder, Krzysztof<br/>Miller, W Allen<br/>2R01 GM067104/GM/NIGMS NIH HHS/United States<br/>Research Support, N.I.H., Extramural<br/>United States<br/>J Biol Chem. 2009 May 22;284(21):14189-202. doi: 10.1074/jbc.M808841200. Epub 2009 Mar 10.