Identification and molecular characterisation of CmeB, a Campylobacter jejuni multidrug efflux pump

Authors

  • Lilian Pumbwe,

    1. Antimicrobial Agents Research Group, Division of Immunity and Infection, The Medical School, University of Birmingham, Birmingham B15 2TT, UK
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  • Laura J.V. Piddock

    Corresponding author
    1. Antimicrobial Agents Research Group, Division of Immunity and Infection, The Medical School, University of Birmingham, Birmingham B15 2TT, UK
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*Corresponding author. Tel.: +44 (121) 414 7915; Fax: +44 (121) 414 3457, E-mail: l.j.v.piddock@bham.ac.uk

Abstract

A multidrug efflux pump gene (cmeB) was identified from the published Campylobacter jejuni genome sequence. Secondary structural analysis showed that the gene encoded a protein belonging to the resistance nodulation cell division (RND) family of efflux transporters. The gene was inactivated by insertional mutagenesis. Compared with the wild-type strain (NCTC 11168), the resultant knockout strain (NCTC 11168-cmeB::kanr) displayed increased susceptibility to a range of antibiotics including β-lactams, fluoroquinolones, macrolides, chloramphenicol, tetracycline, ethidium bromide, the dye acridine orange and the detergent sodium dodecyl sulfate. Accumulation of ciprofloxacin was increased in the knockout mutant, but carbonyl cyanide m-chlorophenyl hydrazone, a proton motive force inhibitor, had less effect upon ciprofloxacin accumulation in the knockout mutant compared with NCTC 11168. These data show that the identified gene encodes an RND-type multi-substrate efflux transporter, which contributes to intrinsic resistance to a range of structurally unrelated compounds in C. jejuni. This efflux pump has been named CmeB (for Campylobactermultidrug efflux).

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