Characterization of the MSMEG_2631 Gene ( mmp ) Encoding a Multidrug and Toxic Compound Extrusion (MATE) Family Protein in Mycobacterium smegmatis and Exploration of Its Polyspecific Nature Using Biolog Phenotype MicroArray

Abstract

ABSTRACT In Mycobacterium , multidrug efflux pumps can be associated with intrinsic drug resistance. Comparison of putative mycobacterial transport genes revealed a single annotated open reading frame (ORF) for a multidrug and toxic compound extrusion (MATE) family efflux pump in all sequenced mycobacteria except Mycobacterium leprae . Since MATE efflux pumps function as multidrug efflux pumps by conferring resistance to structurally diverse antibiotics and DNA-damaging chemicals, we studied this gene (MSMEG_2631) in M. smegmatis mc 2 155 and determined that it encodes a MATE efflux system that contributes to intrinsic resistance of Mycobacterium . We propose that the MSMEG_2631 gene be named mmp , for m ycobacterial M ATE p rotein. Biolog Phenotype MicroArray data indicated that mmp deletion increased susceptibility for phleomycin, bleomycin, capreomycin, amikacin, kanamycin, cetylpyridinium chloride, and several sulfa drugs. MSMEG_2619 ( efpA ) and MSMEG_3563 mask the effect of mmp deletion due to overlapping efflux capabilities. We present evidence that mmp is a part of an MSMEG_2626-2628-2629-2630-2631 operon regulated by a strong constitutive promoter, initiated from a single transcription start site. All together, our results show that M. smegmatis constitutively encodes an Na + -dependent MATE multidrug efflux pump from mmp in an operon with putative genes encoding proteins for apparently unrelated functions.