MSMEG_5850, a stress-induced TetR protein, involved in global transcription regulation in Mycobacterium smegmatis .

Aim: To decipher the role of MSMEG_5850 in the physiology of mycobacteria. Methods: MSMEG_5850 was knocked out and RNA sequencing was performed. MSMEG_5850 protein was purified from the Escherichia coli pET28a system. Electrophoretic mobility shift assay and size exclusion chromatography were used to determine the binding of MSMEG_5850 to its motif and binding stoichiometry. The effect of nutritional stress was monitored. Results: Transcriptome analysis revealed the differential expression of 148 genes in an MSMEG_5850 knockout strain. MSMEG_5850 had control over 50 genes because those genes had a binding motif upstream of their sequence. The electrophoretic mobility shift assay showed MSMEG_5850 bound to its motif as a monomer. MSMEG_5850 was upregulated under nutritional stress and promoted the survival of mycobacteria. Conclusion: The study confirms the role of MSMEG_5850 in global transcriptional regulation.