Acylation of viral spike glycoproteins: a feature of enveloped RNA viruses

The covalent attachment of fatty acids to the glycoproteins of orthomyxo-, paramyxo, alpha-, and coronavirus was studied. All enveloped viruses analyzed afford covalently bound fatty acid in at least one species of their spike glycoproteins. No internal components of the viruses studied including the hydrophobic M proteins of myxo- and rhabdoviruses contained fatty acid. Analysis of myxovirus particles devoid of the exposed portions of their spikes revealed that fatty acids are linked to the hydrophobic tail fragment of the glycoprotein which is associated with the viral lipid bilayer. With influenza virus hemagglutinin the fatty acid attachment site could be located at the cyanogen bromide peptide of the small subunit (HA₂) which contains the membrane-embedded region of the polypeptide. The binding of fatty acids to viral glycoproteins occurs in a wide range of host cells including mammalian, avian, and insect cells.