ABSTRACT
Objective To investigate whether Zika virus NS3 has ATP hydrolase and DNA helicase activity. Methods Zika NS3 with His tag was expressed in E.coli BL21 and purified by Nicke lagarose beads.ATP hy-drolysis assay was performed to examinethe ATPase activity of NS3.The dsDNA unwinding activity of NS3 was detected according to the principle of fluorescence resonance energy transfer(FRET).NS3 G198A mutant was generated by site-directed mutagenesis and its enzymatic activity was measured subsequently.Results Zika NS3 was capable of hydrolyzing ATP in vitro[Vmax=2.76 μmol/(L· min),Km=0.11 mmol/L].Moreover, Zika NS3 could unwind dsDNA in vitro as that proved by the fluorescence was enhancement in FRET system.G198A mutation impaired NS3 enzymatic activities, including ATP hydrolysis and dsDNA unwinding activities.Conclu-sions Zika NS3 has DNA helicase activity in vitro depending on ATP hydrolysis,and the glycine 198 is impor-tant for its enzymatic activity.