A new dehydratase conferring innate resistance to thiacetazone and intra‐amoebal survival of Mycobacterium smegmatis. Issue 5 (28th March 2015)

• Record Type: Journal Article
• Authors: Carrère‐Kremer, Séverine; Blaise, Mickael; Singh, Vipul K.; Alibaud, Laeticia; Tuaillon, Edouard; Halloum, Iman; van de Weerd, Robert; Guérardel, Yann; Drancourt, Michel; Takiff, Howard; Geurtsen, Jeroen; Kremer, Laurent
• Is Part Of: Molecular microbiology. Volume 96:Issue 5(2015)
• Page Start: 1085
• Page End: 1102
• Publication Date: 2015-03-28
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12992
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>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 <italic>MSMEG</italic><italic>_6754</italic> as essential for the innate resistance of <italic>M</italic><italic>ycobacterium smegmatis</italic> to TAC. Transposon‐mediated and targeted disruption of <italic>MSMEG</italic><italic>_6754</italic> resulted in hypersusceptibility to TAC. Conversely, introduction of <italic>MSMEG</italic><italic>_6754</italic> into <italic>M</italic><italic>ycobacterium tuberculosis</italic> 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 <italic>had</italic><italic>B</italic> dehydratase could be achieved in <italic>M</italic><italic>. smegmatis</italic> and <italic>M</italic><italic>. tuberculosis</italic> only when the strains carried an integrated copy of <italic>MSMEG</italic><italic>_6754</italic>, supporting the idea that MSMEG_6754 and HadB share redundant dehydratase activity. Using <italic>M</italic><italic>. smegmatis‐</italic><italic>A</italic><italic>canthamoeba</italic> co‐cultures, we found that intra‐amoebal growth of the <italic>MSMEG</italic><italic>_6754</italic> deleted strain was significantly reduced compared with the parental strain. This <italic>in vivo</italic> 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 <italic>M</italic><italic>. smegmatis</italic> within the environmental host.</p> </abstract>