(R4643) Palmitoylation of SARS-CoV 2 Spike glycoprotein is important for viral infectivity and pathogenicity

Ahmed Ramadan (University of South Florida)| Robert Deschenes (University of South Florida)| Arunava Roy (University of South Florida)

To date the COVID-19 pandemic has resulted in over 90 M infections and 1.8 M deaths worldwide, and the numbers continue to rise.  The causative virus, SARS–CoV-2, is a betacoronavirus that binds to cells through an interaction between the viral Spike protein (S) and its receptor (ACE2) on the host cell.  The S protein is a 180 kDa glycoprotein comprised of a receptor binding domain, trimerization domain, proteolytic cleavage sites, a single transmembrane domain, and a cytoplasmic tail.   In addition to receptor binding, the S protein plays a key role in viral membrane fusion during the virus entry and virus induced cell-cell fusion. The cytoplasmic tail of the Spike has several conserved cysteines that have previously been shown to be palmitoylated in SARS-CoV and MERS. Recently it was reported in an interactome study (Gordon, D.E et al, 2020) that zDHHC5 and Golga7 are among the top Spike interacting proteins. These two proteins form a complex that functions as palmitoyl-transferase. To investigate the functional significance of palmitoylation on SARS-CoV-2 S protein function and viral infection, we created luciferase/ZsGreen reporter containing HIV-1 derived viral particles pseudo-typed with full length wild-type and mutant SARS CoV-2 S. Using an Acyl-PEGyl Exchange Gel-Shift (APEGS) assay, we show that Spike is palmitoylated on multiple sites.  Then, a series of functional assays were carried out to examine the role of Spike palmitoylation on viral egress, viral infection, and Spike protein trimerization, cleavage and fusion.  Our results support the hypothesis that palmitoylation inhibitors may be a potential therapeutic strategy to inhibit SARS CoV2 and other corona viruses infections