SARS-CoV-2 3CLpro (main protease) regulates caspase activation of gasdermin-D/E pores leading to secretion and extracellular activity of 3CLpro
Peter M. Grin, Kaushal Baid, Hugo César Ramos de Jesus, Nedim Kozarac, Peter A. Bell, Steven Z. Jiang, Reinhild Kappelhoff, Georgina S. Butler, Nathan Georges François Leborgne, Christina L. Pan, Isabel Pablos, Yoan Machado, John C. Vederas, Hugh Kim, Charaf Benarafa, Arinjay Banerjee, Christopher M. Overall
Abstract
SARS-CoV-2 3C-like protease (3CL pro or M pro ) cleaves the SARS-CoV-2 polyprotein and >300 intracellular host proteins to enhance viral replication. By lytic cell death following gasdermin (GSDM) pore formation in cell membranes, antiviral pyroptosis decreases 3CL pro expression and viral replication. Unexpectedly, 3CL pro and nucleocapsid proteins undergo unconventional secretion from infected cells via caspase-activated GSDMD/E pores in the absence of cell lysis. Bronchoalveolar lavage fluid of wild-type SARS-CoV-2-infected mice contains 3CL pro , which decreases in Gsdmd −/− Gsdme −/− mice. We identify new 3CL pro cut-sites in GSDMD at LQ 29 ↓ 30 SS, which blocks pore formation by 3CL pro cleavage at LH 270 ↓N lying adjacent to the caspase activation site (NFLTD 275 ↓G). Cleavage inactivation of GSDMD prevents excessive pore formation, thus countering antiviral pyroptosis and increasing 3CL pro secretion. Extracellular 3CL pro retains activity in serum, dampens platelet activation and aggregation, and inactivates antiviral interferon-λ1. Thus, in countering gasdermin pore formation and pyroptosis in SARS-CoV-2 infection, 3CL pro is secreted with extracellular pathological sequelae.