NS3 protease from hepatitis C virus: Biophysical studies on an intrinsically disordered protein domain

S. Vega, J.L. Neira, C. Marcuello, A. Lostao, O. Abian and A. Velazquez-Campoy. NS3 protease from hepatitis C virus: Biophysical studies on an intrinsically disordered protein domain. International Journal of Molecular Sciences. 2013, Vol. 14(3), p. 13282-2013.

The nonstructural protein 3 (NS3) from the hepatitis C virus (HCV) is responsible for processing the non-structural region of the viral precursor polyprotein in infected hepatic cells. NS3 protease activity, located at the N-terminal domain, is a zinc-dependent serine protease. A zinc ion, required for the hydrolytic activity, has been considered as a structural metal ion essential for the structural integrity of the protein. In addition, NS3 interacts with another cofactor, NS4A, an accessory viral protein that induces a conformational change enhancing the hydrolytic activity. Biophysical studies on the isolated protease domain, whose behavior is similar to that of the full-length protein (e.g. catalytic activity, allosteric mechanism and susceptibility to inhibitors), suggest that a considerable global conformational change in the protein is coupled to zinc binding. Zinc binding to NS3 protease can be considered as a folding event, an extreme case of induced-fit binding. Therefore, NS3 protease is an intrinsically (partially) disordered protein with a complex conformational landscape due to its intrinsic plasticity and to the interaction with its different effectors. In this review we summarize the results from a detailed biophysical characterization of this enzyme.