Hepatitis C Virus

The Hepatitis C Virus belongs to the family of Flaviviridae and is a considerable human pathogen with about 170 million people affected world wide. Its genome consists of a positive single-stranded RNA ((+)ssRNA) which is translated into a polyprotein after infection of the host cell. After initial processing of a host cell peptidase the remaining polyprotein consisting of the non-structural proteins NS2, NS3, NS4 and NS5 is cleaved by viral proteases, leading to release of functional and replication-relevant single proteins. Thus, a moleculare understanding of the HCV polyprotein processing is crucial for developments of antiviral strategies.
During procession of polyprotein NS2-NS5 it is already known that the viral cystein protease NS2 initially cleaves the peptide bond between NS2 and NS3. Subsequently, the serine protease NS3 cleaves the remaining peptide bonds of the polyprotein. The multifunctional NS3 protein first acts as a co-factor for the NS2 proteolytic activity and afterwards changes its function into a combined protease/helicase which is associated with the regulatory binding of the NS4A peptide. Thus, understanding of the conformational change of NS3 and its regulation is of major interest.
The structures of isolated NS2 and NS3 as well as a complex consisting of NS3 and the activation domain NS4A have already been solved by X-ray crystallography. As NS4a is considered to function as a molecular switch, the interaction of NS2, NS3 and NS4a with each other is the focus of interest. Thus, aim of this project is to analyse the interaction of NS3 with different peptides of the acidic NS4a domain by dynamic light scattering (DLS)and small angle x-ray scattering (SAXS) in solution. Additionally, we want to characterize the binding epitopes by mass spectrometry and NMR-methods followed by co-crystallization experiments for analysis of molecular details of the complex. The results will provid a basis for development of novel compounds used in the treatment of HCV-infections.

Contact person for this project: Dr. Dirk Rehders