title: Conventional and unconventional mechanisms for capping viral mRNA.
abstract: 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.
authors.affiliation: Centre National de Recherche Scientifique and Aix-Marseille Université, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, 163 avenue de Luminy, 13288 Marseille cedex 09, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Decroly
authors.forename: François
authors.initials: F
authors.lastname: Ferron
authors.forename: Julien
authors.initials: J
authors.lastname: Lescar
authors.forename: Bruno
authors.initials: B
authors.lastname: Canard
mesh_terms: D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D008954:Models, Biological; D008958:Models, Molecular; D012315:RNA Caps / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D012315:RNA Caps; D012367:RNA, Viral; D014764:Viral Proteins; D006147:Guanine; C008450:7-methylguanine