Palmitoylation of SARS‐CoV‐2 Spike Protein is prevented by Fatty Acid Synthase Inhibitors

Mekhail, Katrina

The COVID‐19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV2), has resulted in a significant loss of human life due in part to the paucity of therapeutic options for treatment of the disease. The Spike glycoprotein is responsible for the attachment and infection of host cell and as such it is the target of many countermeasures including vaccines. Most of these therapeutics focus only on the ectodomain of the protein leaving the cytosolic domain of the Spike protein largely unexplored. Our study focuses on the cytosolic domain of the Spike protein as it conserved amongst coronaviruses. This domain contains numerous highly conserved cysteine (cys) residues that are potential sites of S‐palmitoylation; a post‐translational modification mediated by the host enzymes (palmitoyltransferases) that add palmitate to the target protein. In other coronaviruses, palmitoylation of the cytosolic domain of the Spike protein is required for its partitioning into de novo synthesized viral progeny. Here we investigated the cytosolic domain of Spike and its interaction with the protein palmitoyltransferase ZDHHC5. We have found that the Spike protein is palmitoylated on multiple juxtamembrane cysteine residues. Additionally, increased abundance of ZDHHC5 resulted in hyper‐palmitoylation of Spike while silencing of ZDHHC5 reduced palmitoylation as well as the ability of the human coronavirus 229E to form viral plaques in cell monolayers. We used a fatty acid synthase inhibitor TVB‐3166 to reduce palmitoyl‐CoA levels which in turn eliminated palmitoylation of SARS‐CoV2 Spike. Treating cells with TVB‐3166 attenuates the ability of human coronavirus 229E to form plaques and promoted the survival of mice from a lethal murine coronavirus infection. Thus, inhibition of the Spike protein palmitoylation has the potential to treat SARS‐CoV‐2 and other coronavirus infections.