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Título

Cap-snatching mechanism in yeast L-A double-stranded RNA virus

AutorFujimura, Tsutomu; Esteban, Rosa
Fecha de publicación2011
EditorNational Academy of Sciences (U.S.)
CitaciónProceedings of the National Academy of Sciences 108: 17667-17671 (2011)
ResumenThe 5′ cap structure (m7GpppX-) is an essential feature of eukaryotic mRNA required for mRNA stability and efficient translation. Influenza virus furnishes its mRNA with this structure by a cap-snatching mechanism, in which the viral polymerase cleaves host mRNA endonucleolytically 10–13 nucleotides from the 5′ end and utilizes the capped fragment as a primer to synthesize viral transcripts. Here we report a unique cap-snatching mechanism by which the yeast double-stranded RNA totivirus L-A furnishes its transcript with a cap structure derived from mRNA. Unlike influenza virus, L-A transfers only m7Gp from the cap donor to the 5′ end of the viral transcript, thus preserving the 5′ α- and β-phosphates of the transcript in the triphosphate linkage of the final product. This in vitro capping reaction requires His154 of the coat protein Gag, a residue essential for decapping of host mRNA and known to form m7Gp-His adduct. Furthermore, the synthesis of capped viral transcripts in vivo and their expression were greatly compromised by the Arg154 mutation, indicating the involvement of Gag in the cap-snatching reaction. The overall reaction and the structure around the catalytic site in Gag resemble those of guanylyltransferase, a key enzyme of cellular mRNA capping, suggesting convergent evolution. Given that Pol of L-A is confined inside the virion and unable to access host mRNA in the cytoplasm, the structural protein Gag rather than Pol catalyzing this unique cap-snatching reaction exemplifies the versatility as well as the adaptability of eukaryotic RNA viruses
DescripciónEl pdf del artículo es la versión pre-print.
Versión del editorhttp://dx.doi.org/10.1073/pnas.1111900108
URIhttp://hdl.handle.net/10261/51378
DOI10.1073/pnas.1111900108
Identificadoresdoi: 10.1073/pnas.1111900108
e-issn: 1091-6490
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