Inhibition of SARS-CoV-2 Main Protease: A Repurposing Study That Targets the Dimer Interface of the Protein

Coronavirus disease-2019 (COVID-19) was firstly reported in Wuhan, China, towards the end of 2019, and, unfortunately, within a short period of time, emerged as a pandemic. The spread and lethality rates of the COVID-19 have ignited studies that focus on the development of therapeutics for either treatment or prophylaxis purposes. In parallel, drug repurposing studies have also come into prominence. In this study, we aimed at having a holistic understanding of
conformational and dynamical changes induced by an experimentally characterized inhibitor on main protease (M-pro) which would enable the discovery of novel inhibitors. To this end, we performed molecular dynamics simulations using crystal structures of apo and α-ketoamide-13b-bound M-pro homodimer. Analysis of trajectories pertaining to apo M-pro revealed a new target site, which is located at the homodimer interface, next to the catalytic dyad. Thereafter, we performed ensemble-based virtual screening by exploiting the ZINC and DrugBank databases and identified three candidate molecules, namely eluxadoline, diosmin, and ZINC02948810 that could invoke local and global conformational rearrangements which were also elicited by α-ketoamide-13b on the catalytic dyad of M-pro. Furthermore, ZINC23881687 was also discerned as a promising candidate due to its interaction with catalytically important residues Glu166 and Ser1. Last but not least, we could find another candidate, namely ZINC20425029, whose mode of action was different. It modulated the dynamical properties of catalytically important residue, Ala285 rather than the catalytic dyad. As such, this study presents valuable findings that might be used in the development of novel therapeutics against SARS-CoV-2 M-pro.