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|標題:||Mutational analysis of a helicase motif-based RNA 5 '-triphosphatase/NTPase from bamboo mosaic virus||作者:||Han, Y.T.
|關鍵字:||RNA 5 '-triphosphatase;NTPase;ATPase;helicase-like protein;bamboo;mosaic virus;potexvirus;alphavirus-like superfamily;gene-block protein-1;lambda 1 protein;nucleoside triphosphatase;capping enzyme;ns3 protein;dependent guanylyltransferase;s-adenosylmethionine;crystal-structures;covalent complex;dna helicase||Project:||Virology||期刊/報告no：:||Virology, Volume 367, Issue 1, Page(s) 41-50.||摘要:||
The helicase-like domain of BaMV replicase possesses NTPase and RNA 5'-triphosphatase activities. In this study, mutational effects of the helicase signature motifs and residue L543 on the two activities were investigated. Either activity was inactivated by K643A-S644A, D702A, D730A, R855A, or L543P mutations. On the other hand, Q826A, D858A and L543A had activities, in terms of k(cat)/K-m, reduced by 5- to 15-fold. AMPPNP, a nonhydrolyzable ATP analogue, competitively inhibited RNA 5'-triphosphatase activity. Analogies of mutational effects on the two activities and approximation of K-i(AMPPNp) and K-m(ATP) suggest that the catalytic sites of the activities are overlapped. Mutational effects on the viral accumulation in Chenopodium quinoa indicated that the activities manifested by the domain are required for BaMV survival. Results also suggest that Q826 in motif V plays an additional role in preventing tight binding to ATP, which would otherwise decrease further RNA 5'-triphosphatase, leading to demise of the virus in plant. (C) 2007 Elsevier Inc. All rights reserved.
|Appears in Collections:||生物科技學研究所|
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