title: Mycothiol biosynthesis is essential for ethionamide susceptibility in Mycobacterium tuberculosis.
abstract: Spontaneous mutants of Mycobacterium tuberculosis that were resistant to the anti-tuberculosis drugs ethionamide and isoniazid were isolated and found to map to mshA, a gene encoding the first enzyme involved in the biosynthesis of mycothiol, a major low-molecular-weight thiol in M. tuberculosis. Seven independent missense or frameshift mutations within mshA were identified and characterized. Precise null deletion mutations of the mshA gene were generated by specialized transduction in three different strains of M. tuberculosis. The mshA deletion mutants were defective in mycothiol biosynthesis, were only ethionamide-resistant and required catalase to grow. Biochemical studies suggested that the mechanism of ethionamide resistance in mshA mutants was likely due to a defect in ethionamide activation. In vivo, a mycothiol-deficient strain grew normally in immunodeficient mice, but was slightly defective for growth in immunocompetent mice. Mutations in mshA demonstrate the non-essentiality of mycothiol for growth in vitro and in vivo, and provide a novel mechanism of ethionamide resistance in M. tuberculosis.
authors.affiliation: Howard Hughes Medical Institute, Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Vilchèze
authors.forename: Yossef
authors.initials: Y
authors.lastname: Av-Gay
authors.forename: Rodgoun
authors.initials: R
authors.lastname: Attarian
authors.forename: Zhen
authors.initials: Z
authors.lastname: Liu
authors.forename: Manzour H
authors.initials: MH
authors.lastname: Hazbón
authors.forename: Roberto
authors.initials: R
authors.lastname: Colangeli
authors.forename: Bing
authors.initials: B
authors.lastname: Chen
authors.forename: Weijun
authors.initials: W
authors.lastname: Liu
authors.forename: David
authors.initials: D
authors.lastname: Alland
authors.forename: James C
authors.initials: JC
authors.lastname: Sacchettini
authors.forename: William R
authors.initials: WR
authors.lastname: Jacobs
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000235:genetics; D003545:Cysteine / Q000096:biosynthesis* / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005000:Ethionamide / Q000494:pharmacology*; D006020:Glycopeptides / Q000096:biosynthesis* / Q000235:genetics; D016695:Glycosyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007294:Inositol / Q000096:biosynthesis* / Q000235:genetics; D007538:Isoniazid / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D008826:Microbial Sensitivity Tests; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009164:Mycobacterium Infections / Q000188:drug therapy / Q000382:microbiology*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017384:Sequence Deletion; D018088:Tuberculosis, Multidrug-Resistant
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D006020:Glycopeptides; C089265:mycothiol; D007294:Inositol; D006899:Mixed Function Oxygenases; D002374:Catalase; D016695:Glycosyltransferases; D003545:Cysteine; D005000:Ethionamide; D007538:Isoniazid