A GntR family transcription factor positively regulates mycobacterial isoniazid resistance by controlling the expression of a putative permease

Abstract

BackgroundBacteria use transcriptional regulation to respond to environmental stresses. Specifically, exposure to antibacterial drugs is deemed to be an atypical stress, and altering transcriptional regulation in response to such stress can increase bacterial drug resistance. However, only a few transcription factors that regulate drug resistance have been reported.ResultsIn the present study, a GntR family transcription factor, encoded by the MSMEG_0535 (Ms0535) gene, was shown to be an isoniazid (INH) resistance regulator in Mycobacterium smegmatis. When the Ms0535 gene was overexpressed, cells showed a significant increase in INH resistance. First, the interaction between Ms0535 and its own promoter was determined, and a conserved 26-bp palindromic DNA binding motif was identified using electrophoretic mobility shift and DNaseI footprinting assays. Second, quantitative reverse transcription-PCR assays showed that Ms0535 acted as a transcriptional activator, and positively regulated its own expression, as well as that of a permease encoded by the MSMEG_0534 (Ms0534) gene. Similar to the case for the Ms0535 gene, a recombinant Ms0534-overexpressing strain also exhibited increased INH resistance compared with the wild-type strain. Furthermore, we showed that Ms0535 and Ms0534 deletion strains were more sensitive to INH than the wild-type strain. Interestingly, overexpressing Ms0534 in the Ms0535 deletion strain enhanced its INH resistance. In contrast, the Ms0534 deletion strain was still sensitive to INH even when Ms0535 was overexpressed. These findings suggest that Ms0534 is an effector protein that affects INH resistance in M. smegmatis.ConclusionsIn summary, the GntR transcriptional regulator Ms0535 positively regulates INH resistance by transcriptionally regulating the expression of the Ms0534 permease in M. smegmatis. These results improve our understanding of the role of transcriptional regulation in INH drug resistance in mycobacteria.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0556-8) contains supplementary material, which is available to authorized users.

Proteomic Signatures of Clostridium difficile Stressed with Metronidazole, Vancomycin, or Fidaxomicin

“…In detail, overexpression of the GntR-family protein Rv1152 from M. tuberculosis results in higher resistance towards vancomycin [ 50 ]. In M. smegmatis overexpression of the GntR-family protein Ms0535 leads to enhanced resistance towards isoniazid, whose metabolite inhibits cell wall synthesis [ 51 ]. Additionally, the data obtained in this study may suggest a putative role of GntR-family proteins in the detoxification of the transcriptional inhibitor fidaxomicin.…”

Proteomic Adaptation of Clostridioides difficile to Treatment with the Antimicrobial Peptide Nisin

“…GntR family members fulfil various biological functions in diverse bacterial groups. Amongst others, GntR-like proteins are involved in resistance to antimicrobial compounds including vancomycin and isoniazid, which inhibit cell wall synthesis [ 59 , 60 , 61 ]. In this study, we found the GntR-like protein CDIF630erm_01007 with significantly altered amounts after the addition of nisin to C. difficile .…”

Novel TetR family transcriptional factor regulates expression of multiple transport-related genes and affects rifampicin resistance in Mycobacterium smegmatis

“…Utilizing the transcriptional factor overexpression library of M. smegmatis constructed previously 20 , we screened the regulator-overexpressing strains on 7H10 plates containing 1.5 μg/mL RIF and identified a TetR family regulator in M. smegmatis , Ms4022 ( Fig. 1A ), which is associated with RIF resistance.…”

“…Drug-specific response transcription factors also exist. Such as, FurA, OhrR and Ms0535 showed specific drug resistance 20 30 31 . In addition, Ms1448, Ms1613, and Ms5278 overexpressed strains could partially inhibit the growth of M. smegmatis .…”