Palmitoylation enhances the stability of porcine epidemic diarrhea virus spike protein by antagonizing its degradation via chaperone-mediated autophagy to facilitate viral proliferation

Porcine epidemic diarrhea (PED) is a highly pathogenic and infectious intestinal disease caused by the PED virus (PEDV) and has inflicted substantial economic losses on the global swine industry. Therefore, it is imperative to explore appropriate targets to restrain PEDV infection. PEDV spike (S) protein is crucial for viral infection and is regarded as an ideal target for the development of vaccines and antiviral therapeutics. Palmitoylation is a significant post-translational modification implicated in multiple viral replication cycles. Despite the fact that palmitoylation of certain coronavirus S proteins has been reported, the specific biological significance and underlying molecular mechanisms of PEDV S protein palmitoylation have not been fully defined. In the present study, we uncover that palmitoylation enhances the stability of PEDV S protein to promote viral proliferation. Mechanistically, we identify that a cysteine-rich region within the cytoplasmic tail of PEDV S protein is palmitoylated by the zinc finger Asp-His-His-Cys domain palmitoyltransferase 5 (ZDHHC5). We further illustrate that palmitoylation prevents the recognition of Lys-Phe-Glu-Arg-Gln (KFERQ)-like motif in PEDV S protein by heat shock cognate protein of 70 kDa (HSC70), thereby antagonizing its degradation via chaperone-mediated autophagy (CMA). Collectively, our findings underscore the importance of palmitoylation for PEDV pathogenesis and provide prospective targets for the development of antiviral interventions.