Abstract
The spike proteins of enveloped viruses are transmembrane glycoproteins that typically undergo post-translational attachment of palmitate on cysteine residues on the cytoplasmic facing tail of the protein. The role of spike protein palmitoylation in virus biogenesis and infectivity is being actively studied as a potential target of novel antivirals. Here, we report that palmitoylation of the first five cysteine residues of the C-terminal cysteine-rich domain of the SARS-CoV-2 S protein are indispensable for infection, and palmitoylation-deficient spike mutants are defective in membrane fusion. The DHHC9 palmitoyltransferase interacts with and palmitoylates the spike protein in the ER and Golgi and knockdown of DHHC9 results in reduced fusion and infection of SARS-CoV-2. Two bis-piperazine backbone-based DHHC9 inhibitors inhibit SARS-CoV-2 S protein palmitoylation and the resulting progeny virion particles released are defective in fusion and infection. This establishes these palmitoyltransferase inhibitors as potential new intervention strategies against SARS-CoV-2.
Highlights
We show that these novel compounds inhibit palmitoylation of the SARS-CoV-2 spike protein, resulting in reduced virus infectivity
To evaluate if the observed reduction in cellular entry and infectivity of the ∆C, C1, and C2 mutant S pseudotyped lentiviruses is due to defective membrane transport and localization, we investigated the effect of the cysteine cluster mutations on the transport of the S protein to the plasma membrane
We examined whether compounds 13 and 25 inhibited the SARS-CoV-2 S protein palmitoylation using Acyl-PEGyl Exchange Gel-Shift (APEGS) assay
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The last two decades have seen the emergence of three significant coronavirus (CoV). Outbreaks, including the Severe Acute Respiratory Syndrome-CoV (SARS-CoV) in 2002, the Middle East Respiratory Syndrome-CoV (MERS-CoV) in 2012, and most recently, the SARS-CoV-2 in 2020. Β-Coronaviruses are enveloped, positive-stranded RNA viruses that express a spike protein on their surface. The SARS-CoV-2 spike glycoprotein (S) is a 1273 amino acid, type I membrane protein that binds to the ACE2 receptor on the host cell surface to initiate infection, virus uptake, and cell–cell fusion [1,2]. The unprocessed S protein precursor consists of an N-terminal signal sequence for endoplasmic reticulum (ER)
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