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Analysis of the nucleoside triphosphatase, RNA triphosphatase, and unwinding activities of the helicase domain of dengue virus NS3 protein.

Research paper by Chun-Chung CC Wang, Zhi-Shun ZS Huang, Pei-Ling PL Chiang, Chien-Tsun CT Chen, Huey-Nan HN Wu

Indexed on: 27 Jan '09Published on: 27 Jan '09Published in: FEBS Letters



Abstract

The helicase domain of dengue virus NS3 protein (DENV NS3H) contains RNA-stimulated nucleoside triphosphatase (NTPase), ATPase/helicase, and RNA 5'-triphosphatase (RTPase) activities that are essential for viral RNA replication and capping. Here, we show that DENV NS3H unwinds 3'-tailed duplex with an RNA but not a DNA loading strand, and the helicase activity is poorly processive. The substrate of the divalent cation-dependent RTPase activity is not restricted to viral RNA 5'-terminus, a protruding 5'-terminus made the RNA 5'-triphosphate readily accessible to DENV NS3H. DENV NS3H preferentially binds RNA to DNA, and the functional interaction with RNA is sensitive to ionic strength.