Analysis of the topology of Vibrio cholerae NorM and identification of amino acid residues involved in norfloxacin resistance.

ABSTRACT: NorM, a putative efflux pump of Vibrio cholerae, is a member of the multidrug and toxic compound extrusion family of transporters. We demonstrate that NorM confers resistance to norfloxacin, ciprofloxacin, and ethidium bromide. Inactivation of norM rendered V. cholerae hypersensitive towards these fluoroquinolones. Multiple sequence alignment of members of its family identified several regions of high sequence conservation. The topology of NorM was determined using beta-lactamase and chloramphenicol acetyltransferase fusions. The amino acid residues G(184), K(185), G(187), P(189), E(190), G(192), and G(195) in the periplasmic loops and L(381), R(382), G(383), Y(384), K(385), and D(386) in the cytoplasmic loops, as well as all the acidic and cysteine residues of NorM, were mutated. Mutants

SUBMITTER: Singh AK 

PROVIDER: S-EPMC1635172 | biostudies-literature | 2006 Nov

REPOSITORIES: biostudies-literature