MSMEI_4050 modulates resistance to the antitubercular drug rifampicin in Mycolicibacterium smegmatis.

OBJECTIVES

Drug-resistant tuberculosis increases the risk of first-line drugs failure, and one strategy involves the identification of new molecular mechanisms of drug resistance. Mycobacterium tuberculosis lipases play a role in the synthesis of bacterial cell wall lipids. In addition, different studies have shown that lipases are associated with drug resistance. The NLH-H protein (Rv1399c) from M. tuberculosis has been characterized, and its overexpression decreases susceptibility to tetrahydrolipstatin. The MSMEI_4050 gene of Mycolicibacterium smegmatis encoded a protein which has more than 30% identity with the NLN-H protein and shares the SER-ARG-HIS catalytic triad. The aim of this study was to evaluate the effect of MSMEI_4050 expression on drug resistance in M. smegmatis as a M. tuberculosis model.

METHODS

MSMEI_4050 gene overexpression and inhibition were achieved by using the pMV261 vector and CRISPR interference system, respectively. Confirmation of gene expression was determined using qPCR. To evaluate the effect of MSMEI_4050 expression on drug resistance, resazurin microtiter assays and kinetic growth curves were generated. Additionally, molecular docking modeling assays were performed.

RESULTS

The results demonstrated that the overexpression of MSMEI_4050 decreased rifampicin resistance in M. smegmatis, whereas the opposite effect was observed upon MSMEI_4050 inhibition. Molecular docking analysis revealed a positive value of the change in Gibbs free energy estimation between MSMEI_4050 and rifampicin, suggesting that no direct protein‒drug interaction occurs at the active site of the protein.

CONCLUSIONS

MSMEI_4050 expression is associated with rifampicin resistance; further studies are needed to understand the role of MSMEI_4050 in the mechanism underlying rifampicin resistance.