title: Covalent modification of theMycobacterium tuberculosisFAS-II dehydratase by Isoxyl and Thiacetazone.
abstract: Isoxyl and Thiacetazone are two antitubercular prodrugs formerly used in the clinical treatment of tuberculosis. Although both prodrugs have recently been shown to killMycobacterium tuberculosisthrough the inhibition of the dehydration step of the type II fatty acid synthase pathway, their detailed mechanism of inhibition, the precise number of enzymes involved in their activation and the nature of their activated forms remained unknown. We here demonstrate that both Isoxyl and Thiacetazone specifically and covalently react with a cysteine residue (Cys61) of the HadA subunit of the dehydratase thereby inhibiting HadAB activity. Our results unveil for the first time the nature of the active forms of Isoxyl and Thiacetazone and explain the basis for the structure-activity relationship of and resistance to these thiourea prodrugs. Our results further indicate that the flavin-containing monooxygenase EthA is most likely the only enzyme required for the activation of ISO and TAC in mycobacteria.
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Anna E
authors.initials: AE
authors.lastname: Grzegorzewicz
authors.affiliation: CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale), UMR5089, Département Tuberculose et Biologie des Infections, 205 route de Narbonne, F-31077 Toulouse, France ; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Eynard
authors.affiliation: CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale), UMR5089, Département Tuberculose et Biologie des Infections, 205 route de Narbonne, F-31077 Toulouse, France ; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France.
authors.forename: Annaïk
authors.initials: A
authors.lastname: Quémard
authors.affiliation: Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: E Jeffrey
authors.initials: EJ
authors.lastname: North
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Alyssa
authors.initials: A
authors.lastname: Margolis
authors.affiliation: Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606-3390, USA.
authors.forename: Jared J
authors.initials: JJ
authors.lastname: Lindenberger
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Jones
authors.affiliation: Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Mlynska dolina CH-1, 84215 Bratislava, Slovak Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Korduláková
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Brennan
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606-3390, USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Ronning
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: McNeil
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Jackson
keywords: FAS-II; Isoxyl; Mycobacterium; Thiacetazone; dehydratase; tuberculosis