Orphan response regulator Rv3143 increases antibiotic sensitivity by regulating cell wall permeability in Mycobacterium smegmatis.

About one quarter of people worldwide are infected with tuberculosis, and multi-drug resistant tuberculosis (MDR-TB) remains a health threat. It is known that two-Component Signal Transduction Systems (TCSs) of Mycobacterium tuberculosis are closely related to tuberculosis resistance, but the mechanism by which orphan response protein Rv3143 regulates strain sensitivity to drug is still unclear. This study found that Rv3143 overexpression resulted in approximately two-fold increase in Mycobacterium smegmatis antibiotic sensitivity. Transcriptome sequencing indicated that 198 potential genes were regulated by Rv3143, affecting the sensitivity of the strain to rifampicin (RIF). MSMEG_4740 promoter binding with Rv3143, was screened out by surface plasmon resonance (SPR). Rv1524, the homologous gene of MSMEG_4740, belonging to the glycosyltransferase (Gtf) family, was related to cell wall modification. By measuring ethidium bromide (EB) accumulation, we found when Rv3143 or MSMEG_4740, or Rv1524 was overexpressed, the cell wall permeability of Mycobacterium smegmatis was increased. In addition, a combination of Rv3143 and RIF was observed. Our findings provide a new strategy for treating drug-resistant tuberculosis by increasing the expression of Rv3143 to enhance the strain sensitivity to antibiotics.