title: Mechanism of inhibition of Mycobacterium tuberculosis antigen 85 by ebselen.
abstract: The increasing prevalence of drug-resistant tuberculosis highlights the need for identifying new antitubercular drugs that can treat these infections. The antigen 85 (Ag85) complex has emerged as an intriguing mycobacterial drug target due to its central role in synthesizing major components of the inner and outer leaflets of the mycobacterial outer membrane. Here we identify ebselen (EBS) as a potent inhibitor of the Mycobacterium tuberculosis Ag85 complex. Mass spectrometry data show that EBS binds covalently to a cysteine residue (C209) located near the Ag85C active site. The crystal structure of Ag85C in the presence of EBS shows that C209 modification restructures the active site, thereby disrupting the hydrogen-bonded network within the active site that is essential for enzymatic activity. C209 mutations display marked decreases in enzymatic activity. These data suggest that compounds using this mechanism of action will strongly inhibit the Ag85 complex and minimize the selection of drug resistance.
authors.affiliation: Department of Chemistry, University of Toledo, Toledo, Ohio 43606-3390, USA.
authors.forename: Lorenza
authors.initials: L
authors.lastname: Favrot
authors.forename: Anna E
authors.initials: AE
authors.lastname: Grzegorzewicz
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Lajiness
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Marvin
authors.forename: Julie
authors.initials: J
authors.lastname: Boucau
authors.forename: Dragan
authors.initials: D
authors.lastname: Isailovic
authors.forename: Mary
authors.initials: M
authors.lastname: Jackson
authors.forename: Donald R
authors.initials: DR
authors.lastname: Ronning
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000494:pharmacology*; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001393:Azoles / Q000737:chemistry / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D054833:Isoindoles; D008565:Membrane Proteins; D008958:Models, Molecular; D015394:Molecular Structure; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D016566:Organoselenium Compounds / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D011487:Protein Conformation; D029701:Saccharomyces cerevisiae Proteins
chemical_list: C438144:ASI1 protein, S cerevisiae; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000942:Antigens, Bacterial; D001393:Azoles; D054833:Isoindoles; D008565:Membrane Proteins; D016566:Organoselenium Compounds; D029701:Saccharomyces cerevisiae Proteins; C072681:Mycobacterium tuberculosis antigens; C042986:ebselen