A POINT MUTATION ABOLISHES THE HELICASE BUT NOT THE NUCLEOSIDE TRIPHOSPHATASE-ACTIVITY OF HEPATITIS-C VIRUS NS3 PROTEIN

The NS3 protein of hepatitis C virus contains a bipartite structure co nsisting of an N-terminal serine pro tease and a C-terminal DEAD bos h elicase. We show that the C-terminal domain has ATPase and panhelicase activities. The integrity of the helicase function is dependent on th e conserved DEAD motif and can be abolished by a His-Ala point mutatio n, leaving a fully functional nucleoside triphosphatase.