Objective: Clofazimine plays an important role in the treatment of drug-resistant tuberculosis. However, the mechanism of clofazimine resistance remains unclear. In order to slow down the occurrence of clofazimine resistance, it is necessary to study its resistance mechanism.
Methods: In this study, we constructed Rv1453 knockout, complementary and overexpressed strain. The minimum inhibitory concentration (MIC) of clofazimine against Mycobacterium tuberculosis  was detected by microplate alamar blue assay (MABA). The transcription levels of Rv1453  and its adjacent genes were detected by quantitative reverse transcriptase PCR. The purified Rv1453 protein was used for electrophoretic mobility shift assay (EMSA) to identify the binding site of Rv1453 protein.
Results: The minimum inhibitory concentration (MIC) of clofazimine increased about 4-fold for the Rv1453  knockout strain and decreased about 4-fold for the Rv1453  overexpressed strain compared with Mycobacterium tuberculosis  H37Rv. Further analysis showed that Rv1453 protein, as a regulatory protein, binds to the RNA polymerase binding site of qor and blocks the transcription process.
Conclusion: This study preliminarily revealed that Rv1453 protein of Mycobacterium tuberculosis  affects its susceptibility to clofazimine by regulating the transcription level of qor, which is shedding a new light on the mechanism of clofazimine resistance.
Keywords: resistance mechanisms, transcriptional regulation, electrophoretic mobility shift assay, redox