title: Methylation of newly synthesized viral messenger RNA by an enzyme in vaccinia virus.
abstract: Purified vaccinia virions contain an enzyme that incorporates methyl groups from S-adenosylmethionine into viral RNA synthesized by the core-associated DNA-dependent RNA polymerase. This incorporation, by partially disrupted virions, was dependent on the presence of all four ribonucleoside triphosphates and Mg(++) and was inhibited by actinomycin D. At saturation, 2.3 methyl groups were incorporated per 1000 nucleotides. The methyl-labeled RNA product was sensitive to alkali and ribonucleases and hybridized to filters containing immobilized poly(U) or vaccinia DNA. The methyl groups were not located on the 3'-terminal polyadenylate sequence, nor were they randomly distributed along the RNA chain. The lability of a large portion of the methyl groups to perchloric acid digestion was consistent with an O-methyl linkage, and the chromatographic properties of the alkali-digested material suggested that either the 5'-terminus or up to three consecutive internal nucleotides were methylated. Methylation probably occurs at the macromolecular level, since added vaccinia RNA was a suitable substrate. The failure of heterologous rRNA and tRNA species as well as homopolyribonucleotides to act as substrate suggested that a specific sequence might be required.
mesh_terms: D002250:Carbon Radioisotopes; D002848:Chromatography, DEAE-Cellulose; D004279:DNA, Viral / Q000378:metabolism; D004926:Escherichia coli; D008745:Methylation; D009711:Nucleotides / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism; D012367:RNA, Viral / Q000096:biosynthesis / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D014316:Tritium; D014616:Vaccinia virus / Q000201:enzymology* / Q000378:metabolism; D012359:tRNA Methyltransferases / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D004279:DNA, Viral; D009711:Nucleotides; D012333:RNA, Messenger; D012367:RNA, Viral; D014316:Tritium; D012436:S-Adenosylmethionine; D012343:RNA, Transfer; D012359:tRNA Methyltransferases