The main protease (Mpro) from SARS-CoV-2 triggers plasma clotting in vitro by activating coagulation factors VII and FXII.
Pagotto A., Uliana F., Cavedon E., Nordio G., Pierangelini A., Acquasaliente L., Macchia ML., Bellanda M., Gatto B., De Silvestro G., Marson P., Gregori D., Simioni P., Picotti P., De Filippis V.
Although the connection between COVID-19 and coagulopathy has been clear since the beginning of SARS-CoV-2 pandemic, the underlying molecular mechanisms remain elusive. Available data support that the hyper-coagulant state is sustained by systemic inflammation. Here we show that the SARS-CoV-2 main protease (Mpro) can play a direct role in the activation of coagulation. Adding Mpro to human plasma increased clotting probability by 3-fold. Enzymatic assays and degradomics analysis indicate that Mpro cleaves and activates coagulation factors VII and XII. This activity is compatible with an extended secondary specificity of Mpro for R↓X that diverge from its well-established preference for LQ↓X. This finding is supported by HDX-MS characterization of the Mpro complex with an Arg-containing inhibitor, as well as the proteolytic cleavage of the peptide FTRLR↓SLEN by Mpro. Overall, integrating biochemical, proteomics and structural biology experiments, we unveil a novel mechanism linking SARS-CoV-2 infection to thrombotic complications in COVID-19.