The Golgi S-acylation machinery comprises zDHHC enzymes with major differences in substrate affinity and S-acylation activity

Abstract

S-acylation, the attachment of fatty acids onto cysteine residues, regulates protein trafficking and function and is mediated by a family of zDHHC enzymes. The S-acylation of peripheral membrane proteins has been proposed to occur at the Golgi, catalyzed by an S-acylation machinery that displays little substrate specificity. To advance understanding of how S-acylation of peripheral membrane proteins is handled by Golgi zDHHC enzymes, we investigated interactions between a subset of four Golgi zDHHC enzymes and two S-acylated proteins—synaptosomal-associated protein 25 (SNAP25) and cysteine-string protein (CSP). Our results uncover major differences in substrate recognition and S-acylation by these zDHHC enzymes. The ankyrin-repeat domains of zDHHC17 and zDHHC13 mediated strong and selective interactions with SNAP25/CSP, whereas binding of zDHHC3 and zDHHC7 to these proteins was barely detectable. Despite this, zDHHC3/zDHHC7 could S-acylate SNAP25/CSP more efficiently than zDHHC17, whereas zDHHC13 lacked S-acylation activity toward these proteins. Overall the results of this study support a model in which dynamic intracellular localization of peripheral membrane proteins is achieved by highly selective recruitment by a subset of zDHHC enzymes at the Golgi, combined with highly efficient S-acylation by other Golgi zDHHC enzymes.