EXPRESSION OF A HEPATITIS-C VIRUS NS3 PROTEASE-NS4A FUSION PROTEIN INESCHERICHIA-COLI

Both the NS3 protease and the NS4A protein are required for efficient cleavage of the nonstructural protein region of the hepatitis C virus polyprotein. The NS3 protease domain was fused at its C-terminal end w ith full length NS4A and expressed in Escherichia coli. This protein ( NS3 Delta-NS4A) was purified to apparent homogeneity after refolding f rom extracts recovered from inclusion bodies. During the expression an d purification process, NS3 Delta-NS4A was not auto-processed in eithe r a cis or trans manner at NS3/NS4A junction site, When the k(cat)/K-m values and thermostability of NS3 Delta-NS4A were compared with those for maltose binding protein-NS3 fusion protein (MBP-NS3), which conta ins only NS3 region, the single-chain NS3 Delta-NS4A showed enhanced p roteolytic activities and thermostability. (C) 1998 Academic Press.