title: Unconventional mechanism of mRNA capping by the RNA-dependent RNA polymerase of vesicular stomatitis virus.
abstract: All known eukaryotic and some viral mRNA capping enzymes (CEs) transfer a GMP moiety of GTP to the 5'-diphosphate end of the acceptor RNA via a covalent enzyme-GMP intermediate to generate the cap structure. In striking contrast, the putative CE of vesicular stomatitis virus (VSV), a prototype of nonsegmented negative-strand (NNS) RNA viruses including rabies, measles, and Ebola, incorporates the GDP moiety of GTP into the cap structure of transcribing mRNAs. Here, we report that the RNA-dependent RNA polymerase L protein of VSV catalyzes the capping reaction by an RNA:GDP polyribonucleotidyltransferase activity, in which a 5'-monophosphorylated viral mRNA-start sequence is transferred to GDP generated from GTP via a covalent enzyme-RNA intermediate. Thus, the L proteins of VSV and, by extension, other NNS RNA viruses represent a new class of viral CEs, which have evolved independently from known eukaryotic CEs.
authors.affiliation: Department of Molecular Genetics, Section of Virology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Ogino
authors.forename: Amiya K
authors.initials: AK
authors.lastname: Banerjee
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D012315:RNA Caps / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D013379:Substrate Specificity; D013816:Thermodynamics; D014721:Vesicular stomatitis Indiana virus / Q000201:enzymology*; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D012315:RNA Caps; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D014764:Viral Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; C040530:L protein, vesicular stomatitis virus; D012324:RNA-Dependent RNA Polymerase