Methyltransferase activity of the insect orbivirus JKT-7400: photoaffinity labeling of a minor virion protein, VP4, with S-adenosylmethionine.
JKT-7400 virus is an orbivirus originally isolated from Culex mosquitoes. In earlier work we had described the viral structural proteins and presented evidence suggesting that a minor protein, VP6, located in the viral core was the viral guanylyltransferase. We now show that gradient-purified JKT-7400 virions possess a methyltransferase (MTase) activity which can use GTP or GDP as the methyl acceptor. The apparent Km of the MTase for S-adenosylmethionine (AdoMet) was 25 microM. Photoaffinity labeling experiments in which 3H-[methyl]-AdoMet was incubated with virions or viral cores demonstrated labeling of VP4, a minor protein present in the viral core, suggesting that this protein is the viral MTase. Labeling of VP4 was inhibited by addition of unlabeled AdoMet or S-adenosylhomocysteine (AdoHcy).
Liao
H J
HJ
Department of Molecular Genetics and Microbiology, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey, 08854-5635, USA.
Stollar
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D000330:Aedes / Q000821:virology*; D000345:Affinity Labels / Q000378:metabolism; D000818:Animals; D002213:Capsid / Q000378:metabolism*; D036022:Capsid Proteins; D002478:Cells, Cultured; D006160:Guanosine Triphosphate / Q000378:metabolism; D008780:Methyltransferases / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism; D018163:Orbivirus / Q000201:enzymology*; D012436:S-Adenosylmethionine / Q000378:metabolism; D013379:Substrate Specificity; D014764:Viral Proteins / Q000378:metabolism
D000345:Affinity Labels; D036022:Capsid Proteins; D009711:Nucleotides; C060339:VP4 protein, Rotavirus; D014764:Viral Proteins; D012436:S-Adenosylmethionine; D006160:Guanosine Triphosphate; D008780:Methyltransferases