Dimerization-driven interaction of hepatitis C virus core protein with NS3 helicase

Hepatitis C virus (HCV) infects over 130 million people causing a worldwide epidemic of liver cirrhosis and hepatocellular-carcinoma. Because current HCV treatments are only partially effective, molecular mechanisms involved in HCV propagation are actively being pursued as possible drug targets. Here, we report on a new macromolecular interaction between the HCV capsid core protein and the helicase portion of HCV non-structural protein 3 (NS3h), confirmed by four different biochemical methods. The protease portion of NS3 is not required. Interaction between the two proteins could be disrupted by two types of specific inhibitors of core dimerization, the small molecule SL201 and core106, a C-terminally truncated core protein. Cross-linking experiments suggest that the physical interaction with NS3h is probably driven by core oligomerization. Moreover, SL201 blocks the production of infectious virus, but not the production of a subgenomic HCV replicon by hepatoma cells. Time-of-addition experiments confirm that SL201 has no effect on entry of the virus. These data underline the essential role of core as a key organizer of HCV particle assembly, confirm the importance of oligomerization, reveal the interaction with viral helicase and support a new molecular understanding of the formation of the viral particle at the level of the lipid droplets, before its migration to the site of release and budding.