title: An ethA-ethR-deficient Mycobacterium bovis BCG mutant displays increased adherence to mammalian cells and greater persistence in vivo, which correlate with altered mycolic acid composition.
abstract: Tuberculosis remains a major worldwide epidemic because of its sole etiological agent, Mycobacterium tuberculosis. Ethionamide (ETH) is one of the major antitubercular drugs used to treat infections with multidrug-resistant M. tuberculosis strains. ETH is a prodrug that requires activation within the mycobacterial cell; its bioactivation involves the ethA-ethR locus, which encodes the monooxygenase EthA, while EthR is a transcriptional regulator that binds to the intergenic promoter region of the ethA-ethR locus. While most studies have focused on the role of EthA-EthR in ETH bioactivation, its physiological role in mycobacteria has remained elusive, although a role in bacterial cell detoxification has been proposed. Moreover, the importance of EthA-EthR in vivo has never been reported on. Here we constructed and characterized an EthA-EthR-deficient mutant of Mycobacterium bovis BCG. Our results indicate that absence of the ethA-ethR locus led to greater persistence of M. bovis BCG in the mouse model of mycobacterial infection, which correlated with greater adherence to mammalian cells. Furthermore, analysis of cell wall lipid composition by thin-layer chromatography and mass spectrometry revealed differences between the ethA-ethR KO mutant and the parental strain in the relative amounts of α- and keto-mycolates. Therefore, we propose here that M. bovis BCG ethA-ethR is involved in the cell wall-bound mycolate profile, which impacts mycobacterial adherence properties and in vivo persistence. This study thus provides some experimental clues to the possible physiological role of ethA-ethR and proposes that this locus is a novel factor involved in the modulation of mycobacterial virulence.
authors.affiliation: Department of Microbiology and Immunology Program, Yong Yoo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Michelle Lay Teng
authors.initials: ML
authors.lastname: Ang
authors.forename: Siti Zarina
authors.initials: SZ
authors.lastname: Zainul Rahim
authors.forename: Zarina Zainul Rahim
authors.initials: ZZ
authors.lastname: Siti
authors.forename: Guanghou
authors.initials: G
authors.lastname: Shui
authors.forename: Petronela
authors.initials: P
authors.lastname: Dianiškova
authors.forename: Jan
authors.initials: J
authors.lastname: Madacki
authors.forename: Wenwei
authors.initials: W
authors.lastname: Lin
authors.forename: Vanessa Hui Qi
authors.initials: VH
authors.lastname: Koh
authors.forename: Julia Maria
authors.initials: JM
authors.lastname: Martinez Gomez
authors.forename: Sukumar
authors.initials: S
authors.lastname: Sudarkodi
authors.forename: Anne
authors.initials: A
authors.lastname: Bendt
authors.forename: Markus
authors.initials: M
authors.lastname: Wenk
authors.forename: Katarína
authors.initials: K
authors.lastname: Mikušová
authors.forename: Jana
authors.initials: J
authors.lastname: Korduláková
authors.forename: Kevin
authors.initials: K
authors.lastname: Pethe
authors.forename: Sylvie
authors.initials: S
authors.lastname: Alonso
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology*; D002460:Cell Line; D002473:Cell Wall; D005260:Female; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009163:Mycobacterium bovis / Q000235:genetics* / Q000378:metabolism; D009171:Mycolic Acids / Q000378:metabolism*; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013047:Specific Pathogen-Free Organisms
chemical_list: C481661:EthR protein, Mycobacterium tuberculosis; D009171:Mycolic Acids; D012097:Repressor Proteins; D010088:Oxidoreductases; C480352:ethA protein, Mycobacterium tuberculosis