title: Fluoroquinolone supersusceptibility mediated by outer membrane protein OprH overexpression in Pseudomonas aeruginosa: evidence for involvement of a nonporin pathway.
abstract: Overexpression of Pseudomonas aeruginosa outer membrane protein OprH led to an 8- to 32-fold increase in susceptibility to chloramphenicol and the quinolones nalidixic acid, norfloxacin, ciprofloxacin, and fleroxacin in comparison with the susceptibility of the wild-type strain H103 grown on Mg(2+)-sufficient medium. This was true regardless of whether OprH overexpression was induced by growth of strain H103 on Mg(2+)-deficient medium, the addition of 5 mM m-toluate to cells containing the cloned oprH gene behind the inducible tol promoter in plasmid pGB25, or mutation in the polymyxin-resistant derivative strain H181. In contrast, OprH overexpression failed to reverse the quinolone resistance phenotype of a nalB mutant. OprH was purified to homogeneity by selective detergent solubilization and fast protein liquid chromatography. The addition of OprH to the solution bathing a black lipid bilayer membrane failed to give rise to an increase in membrane conductance. This suggests that OprH is not a porin but, instead, may cause increased uptake of quinolones and chloramphenicol via a non-porin pathway.
authors.affiliation: Department of Microbiology, University of British Columbia, Vancouver, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Young
authors.forename: R E
authors.initials: RE
authors.lastname: Hancock
mesh_terms: D000890:Anti-Infective Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002701:Chloramphenicol / Q000493:pharmacokinetics / Q000494:pharmacology; D002939:Ciprofloxacin / Q000493:pharmacokinetics / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D016576:Fleroxacin / Q000493:pharmacokinetics / Q000494:pharmacology; D015870:Gene Expression / Q000235:genetics; D009643:Norfloxacin / Q000493:pharmacokinetics / Q000494:pharmacology; D018272:Porins; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics
chemical_list: D000890:Anti-Infective Agents; D001425:Bacterial Outer Membrane Proteins; D018272:Porins; D002939:Ciprofloxacin; D002701:Chloramphenicol; D009643:Norfloxacin; D016576:Fleroxacin