Computational study on the binding and unbinding mechanism of HCV NS5B with the inhibitor GS-461203 and substrate using conventional and steered molecular dynamics simulations

Abstract

The active metabolite GS-461203 of hepatitis C virus (HCV) non-structural protein 5B (NS5B) inhibitor sofosbuvir can stall RNA synthesis or replication by competitively inhibiting the natural substrate nucleoside triphosphate like UTP. Unfortunately, S282T mutant can lead to the resistance to sofosbuvir. Here, the detailed binding mechanism and unbinding process of GS-461203 and UTP to HCV NS5B were unraveled by using conventional molecular dynamics (MD) simulation and steered molecular dynamics (SMD) simulation. Our simulation results demonstrate that both polar and nonpolar interactions are favorable for GS-461203 and UTP binding. Meanwhile, we also identified the key residues responsible for GS-461203 and UTP binding in NS5B-RNA together with the three unbinding process steps including translation, reversal of base and ribose and complete divorce. The 2′-fluoro-2′-C-methyl ribose of GS-461203 can form stronger polar and nonpolar interactions with residues S282 and I160 than UTP. The results can also explain the reason why GS-461203 can effectively be incorporated into RNA synthesis or replication. In the S282T mutant system, the binding affinity attenuation of UTP relative to wild type HCV NS5B is less than that of GS-461203. The obtained binding and unbinding mechanism of HCV NS5B with the inhibitor GS-461203 and substrate in our work will provide useful guidance for the development of new and effective HCV NS5B inhibitors with low resistance.