TY - JOUR
T1 - West Nile virus methyltransferase catalyzes two methylations of the viral RNA cap through a substrate-repositioning mechanism
AU - Dong, Hongping
AU - Ren, Suping
AU - Zhang, Bo
AU - Zhou, Yangsheng
AU - Puig-Basagoiti, Francesc
AU - Li, Hongmin
AU - Shi, Pei Yong
PY - 2008/5
Y1 - 2008/5
N2 - Flaviviruses encode a single methyltransferase domain that sequentially catalyzes two methylations of the viral RNA cap, GpppA-RNA→m 7GpppA-RNA→m7GpppAm-RNA, by using S-adenosyl-L-methionine (SAM) as a methyl donor. Crystal structures of flavivirus methyltransferases exhibit distinct binding sites for SAM, GTP, and RNA molecules. Biochemical analysis of West Nile virus methyltransferase shows that the single SAM-binding site donates methyl groups to both N7 and 2′-O positions of the viral RNA cap, the GTP-binding pocket functions only during the 2′-O methylation, and two distinct sets of amino acids in the RNA-binding site are required for the N7 and 2′-O methylations. These results demonstrate that flavivirus methyltransferase catalyzes two cap methylations through a substrate-repositioning mechanism. In this mechanism, guanine N7 of substrate GpppA-RNA is first positioned to SAM to generate m 7GpppA-RNA, after which the m7G moiety is repositioned to the GTP-binding pocket to register the 2′-OH of the adenosine with SAM, generating m7GpppAm-RNA. Because N7 cap methylation is essential for viral replication, inhibitors designed to block the pocket identified for the N7 cap methylation could be developed for flavivirus therapy.
AB - Flaviviruses encode a single methyltransferase domain that sequentially catalyzes two methylations of the viral RNA cap, GpppA-RNA→m 7GpppA-RNA→m7GpppAm-RNA, by using S-adenosyl-L-methionine (SAM) as a methyl donor. Crystal structures of flavivirus methyltransferases exhibit distinct binding sites for SAM, GTP, and RNA molecules. Biochemical analysis of West Nile virus methyltransferase shows that the single SAM-binding site donates methyl groups to both N7 and 2′-O positions of the viral RNA cap, the GTP-binding pocket functions only during the 2′-O methylation, and two distinct sets of amino acids in the RNA-binding site are required for the N7 and 2′-O methylations. These results demonstrate that flavivirus methyltransferase catalyzes two cap methylations through a substrate-repositioning mechanism. In this mechanism, guanine N7 of substrate GpppA-RNA is first positioned to SAM to generate m 7GpppA-RNA, after which the m7G moiety is repositioned to the GTP-binding pocket to register the 2′-OH of the adenosine with SAM, generating m7GpppAm-RNA. Because N7 cap methylation is essential for viral replication, inhibitors designed to block the pocket identified for the N7 cap methylation could be developed for flavivirus therapy.
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U2 - 10.1128/JVI.02202-07
DO - 10.1128/JVI.02202-07
M3 - Article
C2 - 18305027
AN - SCOPUS:42449160175
SN - 0022-538X
VL - 82
SP - 4295
EP - 4307
JO - Journal of virology
JF - Journal of virology
IS - 9
ER -