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A new dehydratase conferring innate resistance to thiacetazone and intra‐amoebal survival of M ycobacterium smegmatis
Author(s) -
CarrèreKremer Séverine,
Blaise Mickael,
Singh Vipul K.,
Alibaud Laeticia,
Tuaillon Edouard,
Halloum Iman,
Weerd Robert,
Guérardel Yann,
Drancourt Michel,
Takiff Howard,
Geurtsen Jeroen,
Kremer Laurent
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12992
Subject(s) - biology , mycobacterium smegmatis , dehydratase , complementation , microbiology and biotechnology , biochemistry , mycobacterium tuberculosis , gene , tuberculosis , phenotype , medicine , pathology
Summary Nontuberculous mycobacteria are innately resistant to most antibiotics, although the mechanisms responsible for their drug resistance remain poorly understood. They are particularly refractory to thiacetazone ( TAC ), a second‐line antitubercular drug. Herein, we identified MSMEG _6754 as essential for the innate resistance of M ycobacterium smegmatis to TAC . Transposon‐mediated and targeted disruption of MSMEG _6754 resulted in hypersusceptibility to TAC . Conversely, introduction of MSMEG _6754 into M ycobacterium tuberculosis increased resistance 100‐fold. Resolution of the crystal structure of MSMEG _6754 revealed a homodimer in which each monomer comprises two hot‐dog domains characteristic of dehydratase‐like proteins and very similar to the HadAB complex involved in mycolic acid biosynthesis. Gene inactivation of the essential had B dehydratase could be achieved in M . smegmatis and M . tuberculosis only when the strains carried an integrated copy of MSMEG _6754 , supporting the idea that MSMEG _6754 and HadB share redundant dehydratase activity. Using M . smegmatis‐ A canthamoeba co‐cultures, we found that intra‐amoebal growth of the MSMEG _6754 deleted strain was significantly reduced compared with the parental strain. This in vivo growth defect was fully restored upon complementation with catalytically active MSMEG _6754 or HadABC , indicating that MSMEG _6754 plays a critical role in the survival of M . smegmatis within the environmental host.