A GntR family transcription factor positively regulates mycobacterial isoniazid resistance by controlling the expression of a putative permease. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Hu, Jialing; Zhao, Lei; Yang, Min
• Is Part Of: BMC microbiology. Volume 15:Issue 1(2015)
• Page Start: 1
• Page End: 11
• Publication Date: 2015-12
• Subjects: Mycobacteria -- GntR -- Isoniazid -- Permease; Microbiology -- Periodicals; 579.05
• DOI: 10.1186/s12866-015-0556-8
• Languages: English
• ISSNs: 1471-2180

Abstract

Abstract Background Bacteria 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. Results In the present study, a GntR family transcription factor, encoded by theMSMEG_0535 (Ms0535) gene, was shown to be an isoniazid (INH) resistance regulator inMycobacterium smegmatis. When theMs0535 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 theMSMEG_0534 (Ms0534) gene. Similar to the case for theMs0535 gene, a recombinantMs0534 -overexpressing strain also exhibited increased INH resistance compared with the wild-type strain. Furthermore, we showed thatMs0535 andMs0534 deletion strains were more sensitive to INH than the wild-type strain. Interestingly, overexpressingMs0534 in theMs0535 deletion strain enhanced its INH resistance. In contrast, theMs0534 deletion strain was still sensitive to INH even whenMs0535 was overexpressed. These findings suggest that Ms0534 is an effector protein that affects INH resistance inM. smegmatis . Conclusions In 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.