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|標題:||mRNA guanylation catalyzed by the S-adenosylmethionine-dependent guanylyltransferase of bamboo mosaic virus||作者:||Huang, Y.L.
|關鍵字:||complete nucleotide-sequence;semliki-forest-virus;capping enzyme;critical residues;covalent complex;genomic rna;potexvirus;methylation;protein;intermediate||Project:||Journal of Biological Chemistry||期刊/報告no：:||Journal of Biological Chemistry, Volume 280, Issue 13, Page(s) 13153-13162.||摘要:||
The S-adenosylmethionine-dependent guanylyltransferase of bamboo mosaic virus belongs to a novel class of mRNA capping enzymes distantly conserved in Alphavirus-like superfamily. The reaction sequence of the viral enzyme has been proposed comprising steps of 1) binding of GTP and S-adenosylmethionine, 2) formation of m(7)GTP and S-adenosylhomocysteine, 3) formation of the covalent (Enzyme-m(7)GMP) intermediate, and 4) transfer of m(7)GMP from the intermediate to the RNA acceptor. In this study the acceptor specificity of the viral enzyme was characterized. The results show that adenylate or guanylate with 5'-diphosphate group is an essential feature for acceptors, which can be RNA or mononucleotide, to receive m7GMP. The transfer rate of m7GMP to guanylate is greater than to adenylate by a factor of similar to 3, and the K-m value for mononucleotide acceptor is similar to 10(3)-fold higher than that for RNA. The capping efficiency of the viral genomic RNA transcript depends on the length of the transcript and the formation of a putative stemloop structure, suggesting that mRNA capping process may participate in regulating the viral gene expression.
|Appears in Collections:||生物科技學研究所|
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