title: Mycobacterium tuberculosis efpA encodes an efflux protein of the QacA transporter family.
abstract: The Mycobacterium tuberculosis H37Rv efpA gene encodes a putative efflux protein, EfpA, of 55,670 Da. The deduced EfpA protein was similar in secondary structure to Pur8, MmrA, TcmA, LfrA, EmrB, and other members of the QacA transporter family (QacA TF) which mediate antibiotic and chemical resistance in bacteria and yeast. The predicted EfpA sequence possessed all transporter motifs characteristic of the QacA TF, including those associated with proton-antiport function and the motif considered to be specific to exporters. The 1,590-bp efpA open reading frame was G+C rich (65%), whereas the 40-bp region immediately upstream had an A+T bias (35% G+C). Reverse transcriptase-PCR assays indicated that efpA was expressed in vitro and in situ. Putative promoter sequences were partially overlapped by the A+T-rich region and by a region capable of forming alternative secondary structures indicative of transcriptional regulation in analogous systems. PCR single-stranded conformational polymorphism analysis demonstrated that these upstream flanking sequences and the 231-bp, 5' coding region are highly conserved among both drug-sensitive and multiply-drug-resistant isolates of M. tuberculosis. The efpA gene was present in the slow-growing human pathogens M. tuberculosis, Mycobacterium leprae, and Mycobacterium bovis and in the opportunistic human pathogens Mycobacterium avium and Mycobacterium intracellular. However, efpA was not present in 17 other opportunistically pathogenic or nonpathogenic mycobacterial species.
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada. jdoran@uvic.ca
authors.forename: J L
authors.initials: JL
authors.lastname: Doran
authors.forename: Y
authors.initials: Y
authors.lastname: Pang
authors.forename: K E
authors.initials: KE
authors.lastname: Mdluli
authors.forename: A J
authors.initials: AJ
authors.lastname: Moran
authors.forename: T C
authors.initials: TC
authors.lastname: Victor
authors.forename: R W
authors.initials: RW
authors.lastname: Stokes
authors.forename: E
authors.initials: E
authors.lastname: Mahenthiralingam
authors.forename: B N
authors.initials: BN
authors.lastname: Kreiswirth
authors.forename: J L
authors.initials: JL
authors.lastname: Butt
authors.forename: G S
authors.initials: GS
authors.lastname: Baron
authors.forename: J D
authors.initials: JD
authors.lastname: Treit
authors.forename: V J
authors.initials: VJ
authors.lastname: Kerr
authors.forename: P D
authors.initials: PD
authors.lastname: Van Helden
authors.forename: M C
authors.initials: MC
authors.lastname: Roberts
authors.forename: F E
authors.initials: FE
authors.lastname: Nano
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000032:analysis* / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D006801:Humans; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009163:Mycobacterium bovis / Q000235:genetics; D009166:Mycobacterium leprae / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D016133:Polymerase Chain Reaction
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; C068498:qacA protein, Staphylococcus aureus