title: Role of lon, an ATP-dependent protease homolog, in resistance of Pseudomonas aeruginosa to ciprofloxacin.
abstract: With few novel antimicrobials in the pharmaceutical pipeline, resistance to the current selection of antibiotics represents a significant therapeutic challenge. Microbial persistence in subinhibitory antibiotic environments has been proposed to contribute to the development of resistance. Pseudomonas aeruginosa cultures pretreated with subinhibitory concentrations of ciprofloxacin were found to exhibit an adaptive resistance phenotype when cultures were subsequently exposed to suprainhibitory ciprofloxacin concentrations. Microarray experiments revealed candidate genes involved in such adaptive resistance. Screening of 10,000 Tn5-luxCDABE mutants identified several mutants with increased or decreased ciprofloxacin susceptibilities, including mutants in PA1803, a close homolog of the ATP-dependent lon protease, which were found to exhibit > or = 4-fold-increased susceptibilities to ciprofloxacin and other fluoroquinolones, but not to gentamicin or imipenem, as well as a characteristic elongated morphology. Complementation of the lon mutant restored wild-type antibiotic susceptibility and cell morphology. Expression of the lon mutant, as monitored through a luciferase reporter fusion, was found to increase over time in the presence of subinhibitory ciprofloxacin concentrations. The data are consistent with the hypothesis that the induction of Lon by ciprofloxacin is involved in adaptive resistance.
authors: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.
authors: Michelle D
authors: MD
authors: Brazas
authors: Elena B M
authors: EB
authors: Breidenstein
authors: Joerg
authors: J
authors: Overhage
authors: Robert E W
authors: RE
authors: Hancock
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D002939:Ciprofloxacin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024841:Fluoroquinolones / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology; D008826:Microbial Sensitivity Tests; D020411:Oligonucleotide Array Sequence Analysis; D049070:Protease La / Q000235:genetics* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000187:drug effects* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D006360:Heat-Shock Proteins; D002939:Ciprofloxacin; D049070:Protease La