NTPASE ACTIVITY OF HEPATITIS-C VIRUS NS3 PROTEIN EXPRESSED IN INSECT CELLS

Abstract

The NS3 protein of hepatitis C virus is known to have a serine-type proteinase, a nucleotide triphosphatase (NTPase), and an RNA helicase activity based on the presence of sequence motifs, We demonstrated that the NS3 protein of hepatitis C virus expressed in insect cells possesses an NTPase activity, Employing a baculovirus expression system, we expressed the NS3 protein and partially purified it using a metal-binding chromatography, We found that two kinds of NS3 proteins were expressed in a baculovirus expression system, The p70 protein is an expected form and the p47 protein seems to be a proteolytic cleavage form of the p70 protein, The p70 protein showed a specific NTPase activity, NTPase activity was completely inhibited by NS3 monoclonal antibodies. Our data strongly suggest that the NS3 protein of HCV expressed in insect cells contains an NTPase activity.