The entry of the coronavirus SARS-CoV-2 into human lung cells can be inhibited by the approved drugs camostat and nafamostat Here we elucidate the molecular mechanism of these drugs by combining experiments and simulations In vitroassays confirm that both drugs inhibit the human protein TMPRSS2, a SARS-Cov-2 spike protein activator As no experimental structure is available, we provide a model of the TMPRSS2 equilibrium structure and its fluctuations by relaxing an initial homology structure with extensive 330 microseconds of all-atom molecular dynamics (MD) and Markov modeling Through Markov modeling, we describe the binding process of both drugs and a metabolic product of camostat (GBPA) to TMPRSS2, reaching a Michaelis complex (MC) state, which precedes the formation of a long-lived covalent inhibitory state We find that nafamostat has a higher MC population than camostat and GBPA, suggesting that nafamostat is more readily available to form the stable covalent enzyme-substrate intermediate, effectively explaining its high potency This model is backed by ourin vitroexperiments and consistent with previous virus cell entry assays Our TMPRSS2-drug structures are made public to guide the design of more potent and specific inhibitors © The Royal Society of Chemistry 2020
Molecular mechanism of inhibiting the SARS-CoV-2 cell entry facilitator TMPRSS2 with camostat and nafamostat