Structural Modifications Introduced by NS2B Cofactor Binding to the NS3 Protease of the Kyasanur Forest Disease Virus

Abstract

Kyasanur Forest Disease virus (KFDV), a neglected human pathogenic virus, is a Flavivirus that causes severe hemorrhagic fever in humans. KFDV is transmitted to humans by the bite of the hard tick (Haemaphysalis spinigera), which acts as a reservoir of KFDV. The recent expansion of the endemic area of KFDV is of concern and requires the development of new preventive measures against KFDV. Currently, there is no antiviral therapy against KFDV, and the existing vaccine has limited efficacy. To develop a new antiviral therapy against KFDV, we focused on the nonstructural proteins NS2B and NS3 of KFDV, which are responsible for serine protease activity. Viral proteases have shown to be suitable therapeutic targets in the development of antiviral drugs against many diseases. However, success has been limited in flaviviruses, mainly because of the important features of the active site, which is flat and highly charged. In this context, the present study focuses on the dynamics of NS2B and NS3 to identify potential allosteric sites in the NS2B/NS3 protease of KDFV. To our knowledge, there are no reports on the dynamics of NS2B and NS3 in KFDV, and the crystal structure of the NS2B/NS3 protease of KFDV has not yet been solved. Overall, we created the structure of the NS2B/NS3 protease of KFDV using AlphaFold and performed molecular dynamics simulations with and without NS2B cofactor to investigate structural rearrangements due to cofactor binding and to identify alternative allosteric sites. The identified allosteric site is promising due to its geometric and physicochemical properties and druggability and can be used for new drug development. The applicability of the proposed allosteric binding sites was verified for the best-hit molecules from the virtual screening and MD simulations.

Molecular Insights into Macromolecules Structure, Function, and Regulation

“…Targeting the newly defined binding pocket, five ligands with potential bioactivities selected with the combination of docking and MD simulations, based on the conformational changes upon ligand binding. A similar research approach was also reflected in the structural dynamic studies of the NS2B/NS3 protease of Kyasanur Forest Disease virus (KFDV), which leads to the onset of severe hemorrhagic fever in humans [10]. As for the study of cholesteryl ester transfer protein (CETP), which is a promising target for mitigating cardiovascular diseases (CVD), the absence of dynamic structural characteristics under physiological conditions (authentic CETP) impedes a comprehensive understanding of the lipid transfer mechanisms and hampers the development of CETP pharmacologic inhibition.…”