title: Profiling targets of the irreversible palmitoylation inhibitor 2-bromopalmitate.
abstract: 2-Bromohexadecanoic acid, or 2-bromopalmitate, was introduced nearly 50 years ago as a nonselective inhibitor of lipid metabolism. More recently, 2-bromopalmitate re-emerged as a general inhibitor of protein S-palmitoylation. Here, we investigate the cellular targets of 2-bromopalmitate through the synthesis and application of click-enabled analogues. In cells, 2-bromopalmitate is converted to 2-bromopalmitoyl-CoA, although less efficiently than free palmitate. Once conjugated to CoA, probe reactivity is dramatically enhanced. Importantly, both 2-bromopalmitate and 2-bromopalmitoyl-CoA label DHHC palmitoyl acyl transferases (PATs), the enzymes that catalyze protein S-palmitoylation. Mass spectrometry analysis of enriched 2-bromopalmitate targets identified PAT enzymes, transporters, and many palmitoylated proteins, with no observed preference for CoA-dependent enzymes. These data question whether 2-bromopalmitate (or 2-bromopalmitoyl-CoA) blocks S-palmitoylation by inhibiting protein acyl transferases, or by blocking palmitate incorporation by direct covalent competition. Overall, these findings highlight the promiscuous reactivity of 2BP and validate clickable 2BP analogues as activity-based probes of diverse membrane associated enzymes.
authors.affiliation: Program in Chemical Biology, ‡Department of Chemistry, and §Department of Pharmacology, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
authors.forename: Dahvid
authors.initials: D
authors.lastname: Davda
authors.forename: Mahmoud A
authors.initials: MA
authors.lastname: El Azzouny
authors.forename: Christopher T M B
authors.initials: CT
authors.lastname: Tom
authors.forename: Jeannie L
authors.initials: JL
authors.lastname: Hernandez
authors.forename: Jaimeen D
authors.initials: JD
authors.lastname: Majmudar
authors.forename: Robert T
authors.initials: RT
authors.lastname: Kennedy
authors.forename: Brent R
authors.initials: BR
authors.lastname: Martin
mesh_terms: D000217:Acyltransferases / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D006801:Humans; D054878:Lipoylation / Q000187:drug effects*; D010168:Palmitates / Q000737:chemistry* / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism*
chemical_list: D010168:Palmitates; D011506:Proteins; C022776:2-bromopalmitate; D000217:Acyltransferases