Ethambutol and isoniazid influence the growth of Mycobacterium smegmatis

Abstract:

[Objective] Isoniazid (INH) and ethambutol (EMB) are the two main first-line drugs for the treatment of tuberculosis (TB), while the underlying synergistic mechanism remains unclear. [Methods] The Ms0606 gene was cloned from Mycobacterium smegmatis and its expression was induced by the addition of 0.5 mmol/L isopropyl β-d-1-thiogalactopyranoside (IPTG) at 37 °C for 4 h. The interaction between Ms0606 protein and EMB was studied by isothermal titration calorimetry (ITC). The effect of EMB on the DNA binding activity of Ms0606 was examined by electrophoretic mobility shift assay (EMSA). The growth curves of the Ms0606-overexpressing strain treated with INH and INH+EMB were established. [Results] Ms0606 protein was purified with high purity. EMB can bind with Ms0606 at a ratio of 1:1 and specifically enhance the DNA binding activity of Ms0606. In the presence of a non-lethal dose of EMB, the overexpression of Ms0606 enhanced the effect of INH on M. smegmatis MC²155. [Conclusion] The TetR family transcriptional regulator encoded by Ms0606 plays a role in the synergistic effect of EMB and INH, the further research on which will help us to understand the regulatory mechanism of bacterial resistance.