Conventional and unconventional mechanisms for capping viral mRNA.

Decroly, Etienne; Ferron, François; Lescar, Julien; Canard, Bruno

In the eukaryotic cell, capping of mRNA 5? ends is an essential structural modification that allows efficient mRNA translation, directs pre-mRNA splicing and mRNA export from the nucleus, limits mRNA degradation by cellular 5?-3? exonucleases and allows recognition of foreign RNAs (including viral transcripts) as 'non-self'. However, viruses have evolved mechanisms to protect their RNA 5? ends with either a covalently attached peptide or a cap moiety (7-methyl-Gppp, in which p is a phosphate group) that is indistinguishable from cellular mRNA cap structures. Viral RNA caps can be stolen from cellular mRNAs or synthesized using either a host- or virus-encoded capping apparatus, and these capping assemblies exhibit a wide diversity in organization, structure and mechanism. Here, we review the strategies used by viruses of eukaryotic cells to produce functional mRNA 5?-caps and escape innate immunity.

EUKARYOTIC cells; MESSENGER RNA; EXONUCLEASES; PEPTIDES; VIRAL genetics

Nature Reviews Microbiology, 2012, Vol 10, Issue 1, p51

1740-1526

Academic Journal

10.1038/nrmicro2675