S-Acylation of Proteins of Coronavirus and Influenza Virus: Conservation of Acylation Sites in Animal Viruses and DHHC Acyltransferases in Their Animal Reservoirs

Abstract

Recent pandemics of zoonotic origin were caused by members of coronavirus (CoV) and influenza A (Flu A) viruses. Their glycoproteins (S in CoV, HA in Flu A) and ion channels (E in CoV, M2 in Flu A) are S-acylated. We show that viruses of all genera and from all hosts contain clusters of acylated cysteines in HA, S and E, consistent with the essential function of the modification. In contrast, some Flu viruses lost the acylated cysteine in M2 during evolution, suggesting that it does not affect viral fitness. Members of the DHHC family catalyze palmitoylation. Twenty-three DHHCs exist in humans, but the number varies between vertebrates. SARS-CoV-2 and Flu A proteins are acylated by an overlapping set of DHHCs in human cells. We show that these DHHC genes also exist in other virus hosts. Localization of amino acid substitutions in the 3D structure of DHHCs provided no evidence that their activity or substrate specificity is disturbed. We speculate that newly emerged CoVs or Flu viruses also depend on S-acylation for replication and will use the human DHHCs for that purpose. This feature makes these DHHCs attractive targets for pan-antiviral drugs.

Identification of SARS-CoV-2 Spike Palmitoylation Inhibitors That Results in Release of Attenuated Virus with Reduced Infectivity

“…This suggests that although it is certain that multiple PATs are involved in S protein palmitoylation, the specific role of each palmitoyltransferase requires additional work. Interestingly, DHHC9 and 20 are expressed in all animal reservoirs of Coronaviruses [ 62 ] and are therefore most likely to play major roles in the regulation of the S protein palmitoylation. Intriguingly, these two PATs were also among the ones that were upregulated when we knocked down DHHC5.…”

“…Interestingly, DHHC9 has been reported to be highly expressed in the lungs, brain, kidney, skeletal muscle, and liver, and to a lesser extent in placenta, heart, colon, and small intestine [ 47 ], many of which are known to be tissues permissive to SARS-CoV-2 infection. Moreover, because the S proteins of many zoonotic viruses are palmitoylated [ 62 ], DHHC inhibitors may have broad antiviral applications. Further work is needed to establish the potential of DHHC PAT inhibitors to be developed into therapeutic drugs.…”

Protein Palmitoylation Modification During Viral Infection and Detection Methods of Palmitoylated Proteins

“…Using CRISPR/Cas9 knockout and siRNA screening, DHHC2, 8, 15, and 20 were found to be involved in S-acylation of HA and M2 of IAV and human influenza viruses . DHHC20, -8, and -9 were verified to play certain roles in SARS-CoV-2 spike protein(S) and enveloped protein (Abdulrahman et al, 2021;Mesquita et al, 2021;Puthenveetil et al, 2021). However, conflicting results regarding the palmitoylation sites and palmitoylation enzymes of SARS-CoV-2 spike protein were obtained by different researchers (Mesquita et al, 2021;Puthenveetil et al, 2021;Zeng et al, 2021;Li et al, 2022).…”

“…The reasons for the conflicting results may be the use of different viruses and cell models or different methods. In addition no specific molecule drug for inhibiting a certain zDHHC substrate interaction has been developed so far (Abdulrahman et al, 2021). Looking forward, we believe that the discovery and identification of enzymes and their specific inhibitors acting on the palmitoylation cycle of viral proteins would be a new challenge and almost certainly would become one of the most interesting topics to investigate.…”

Redox stress in COVID-19: Implications for hematologic disorders

“…Cysteine acylation is the addition of an acyl chain onto a cysteine to help anchor the protein to membranes. Evidences indicating the role of palmitoylation on the S protein for viral entry into the cell have been reported [ [76] , [77] , [78] , [79] , [80] ]. Specifically, the S protein is cysteine palmitoylated by the zDHHC family of palmitoyltransferases.…”