Capping of tobacco mosaic virus RNA. Analysis of viral-coded guanylyltransferase-like activity.
The 5' end of tobacco mosaic virus (TMV) genomic RNA is capped with 7-methylguanosine. A virus-coded polypeptide with guanylyltransferase activity has been investigated. This enzyme is responsible for forming the 5'----5' linkage of guanosine 5'-monophosphate to the 5'-diphosphate of an acceptor RNA, thereby forming the cap. A critical step in the mechanism for cap formation in the eukaryotic nucleus is for guanylyltransferase to bind covalently to guanosine 5'-monophosphate with the hydrolysis of pyrophosphate when guanosine 5'-triphosphate is the substrate. The TMV 126-kilodalton protein, which is most probably a component of the TMV replicase, was found to have this activity. The mechanism of this reaction has been characterized biochemically.
Dunigan
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Department of Plant Pathology, Cornell University, Ithaca, New York 14853.
Zaitlin
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D001667:Binding, Competitive; D002413:Cations, Divalent; D002458:Cell Fractionation; D006150:Guanine Nucleotides / Q000378:metabolism / Q000494:pharmacology; D006151:Guanosine / Q000031:analogs & derivatives / Q000378:metabolism; D006157:Guanosine Monophosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007163:Immunosorbent Techniques; D008970:Molecular Weight; D009711:Nucleotides / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology; D010947:Plants, Toxic; D012315:RNA Caps; D012367:RNA, Viral / Q000378:metabolism*; D013379:Substrate Specificity; D014026:Nicotiana / Q000382:microbiology; D014027:Tobacco Mosaic Virus / Q000201:enzymology / Q000235:genetics*
D002413:Cations, Divalent; D006150:Guanine Nucleotides; D009711:Nucleotides; D010710:Phosphates; D012315:RNA Caps; D012367:RNA, Viral; D006151:Guanosine; C016578:7-methylguanosine; D006157:Guanosine Monophosphate; D006160:Guanosine Triphosphate; D009713:Nucleotidyltransferases; C020842:guanylyltransferase