Separate molecules of West Nile virus methyltransferase can independently catalyze the N7 and 2'-O methylations of viral RNA cap.
West Nile virus methyltransferase catalyzes N7 and 2'-O methylations of the viral RNA cap (GpppA-RNA-->m(7)GpppAm-RNA). The two methylation events are independent, as evidenced by efficient N7 methylation of GpppA-RNA-->m(7)GpppA-RNA and GpppAm-RNA-->m(7)GpppAm-RNA, and by the 2'-O methylation of GpppA-RNA-->GpppAm-RNA and m(7)GpppA-RNA-->m(7)GpppAm-RNA. However, the 2'-O methylation activity prefers substrate m(7)GpppA-RNA to GpppA-RNA, thereby determining the dominant methylation pathway as GpppA-RNA-->m(7)GpppA-RNA-->m(7)GpppAm-RNA. Mutant enzymes with different methylation defects can trans complement one another in vitro. Furthermore, sequential treatment of GpppA-RNA with distinct methyltransferase mutants generates fully methylated m(7)GpppAm-RNA, demonstrating that separate molecules of the enzyme can independently catalyze the two cap methylations in vitro.
Dong
Hongping
H
Wadsworth Center, New York State Department of Health, USA.
Ren
Suping
S
Li
Hongmin
H
Shi
Pei-Yong
PY
D005814:Genes, Viral; D005816:Genetic Complementation Test; D007700:Kinetics; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D012314:RNA Cap Analogs / Q000378:metabolism; D012315:RNA Caps / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014902:West Nile virus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*
D012314:RNA Cap Analogs; D012315:RNA Caps; D012367:RNA, Viral; C509442:m7GpppA; D008780:Methyltransferases