title: Virus-specific capping of tobacco mosaic virus RNA: methylation of GTP prior to formation of covalent complex p126-m7GMP.
abstract: In capping cellular mRNAs, a covalent GMP-enzyme intermediate leads to formation of G(5')ppp(5')N at the 5' end of the RNA, which is modified by methylation catalyzed by guanine-7-methyltransferase. Here we show that isolated membranes from tobacco mosaic virus (TMV)-infected plant or insect cells expressing TMV replicase protein p126, synthesized m7GTP using S-adenosylmethionine (AdoMet) as the methyl donor, and catalyzed the formation of a covalent guanylate-p126 complex in the presence of AdoMet. The methyl group from AdoMet was incorporated into p126, suggesting that the complex consisted of m7GMP-p126. Thus, TMV and alphaviruses, despite their evolutionary distance, share the same virus-specific capping mechanism.
authors.affiliation: Institute of Biotechnology, Biocenter Viikki, University of Helsinki, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Merits
authors.forename: R
authors.initials: R
authors.lastname: Kettunen
authors.forename: K
authors.initials: K
authors.lastname: Mäkinen
authors.forename: A
authors.initials: A
authors.lastname: Lampio
authors.forename: P
authors.initials: P
authors.lastname: Auvinen
authors.forename: L
authors.initials: L
authors.lastname: Kääriäinen
authors.forename: T
authors.initials: T
authors.lastname: Ahola
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D006157:Guanosine Monophosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D007313:Insecta; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000378:metabolism; D017354:Point Mutation; D012315:RNA Caps; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014027:Tobacco Mosaic Virus / Q000235:genetics*
chemical_list: D017931:DNA Primers; D012315:RNA Caps; D012367:RNA, Viral; D011994:Recombinant Proteins; D006157:Guanosine Monophosphate; D006160:Guanosine Triphosphate; D008780:Methyltransferases; D009713:Nucleotidyltransferases