title: Alkyl-CoA disulfides as inhibitors and mechanistic probes for FabH enzymes.
abstract: The first step of the reaction catalyzed by the homodimeric FabH from a dissociated fatty acid synthase is acyl transfer from acyl-CoA to an active site cysteine. We report that C1 to C10 alkyl-CoA disulfides irreversibly inhibit Escherichia coli FabH (ecFabH) and Mycobacterium tuberculosis FabH with relative efficiencies that reflect these enzymes' differential acyl-group specificity. Crystallographic and kinetic studies with MeSSCoA show rapid inhibition of one monomer of ecFabH through formation of a methyl disulfide conjugate with this cysteine. Reaction of the second subunit with either MeSSCoA or acetyl-CoA is much slower. In the presence of malonyl-ACP, the acylation rate of the second subunit is restored to that of the native ecFabH. These observations suggest a catalytic model in which a structurally disordered apo-ecFabH dimer orders on binding either the first substrate, acetyl-CoA, or the inhibitor MeSSCoA, and is restored to a disordered state on binding of malonyl-ACP.
authors.affiliation: Department of Chemistry, Portland State University, Portland, OR 97207, USA.
authors.forename: Mamoun M
authors.initials: MM
authors.lastname: Alhamadsheh
authors.forename: Faik
authors.initials: F
authors.lastname: Musayev
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Komissarov
authors.forename: Sarbjot
authors.initials: S
authors.lastname: Sachdeva
authors.forename: H Tonie
authors.initials: HT
authors.lastname: Wright
authors.forename: Neel
authors.initials: N
authors.lastname: Scarsdale
authors.forename: Galina
authors.initials: G
authors.lastname: Florova
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Reynolds
mesh_terms: D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase / Q000037:antagonists & inhibitors*; D000215:Acylation; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology*; D004926:Escherichia coli / Q000201:enzymology; D005453:Fluorescence; D005470:Fluorometry; D007202:Indicators and Reagents; D007700:Kinetics; D008958:Models, Molecular; D013302:Streptomyces / Q000187:drug effects / Q000201:enzymology
chemical_list: D004220:Disulfides; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; C077402:3-ketoacyl-acyl carrier protein synthase III; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase; D003545:Cysteine