title: Subcellular localization of Pseudomonas pyocyanin cytotoxicity in human lung epithelial cells.
abstract: The Pseudomonas aeruginosa secretory product pyocyanin damages lung epithelium, likely due to redox cycling of pyocyanin and resultant superoxide and H(2)O(2) generation. Subcellular site(s) of pyocyanin redox cycling and toxicity have not been well studied. Therefore, pyocyanin's effects on subcellular parameters in the A549 human type II alveolar epithelial cell line were examined. Confocal and electron microscopy studies suggested mitochondrial redox cycling of pyocyanin and extracellular H(2)O(2) release, respectively. Pyocyanin decreased mitochondrial and cytoplasmic aconitase activity, ATP levels, cellular reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, and mitochondrial membrane potential. These effects were transient at low pyocyanin concentrations and were linked to apparent cell-mediated metabolism of pyocyanin. Overexpression of MnSOD, but not CuZnSOD or catalase, protected cellular aconitase, but not ATP, from pyocyanin-mediated depletion. This suggests that loss of aconitase activity is not responsible for ATP depletion. How pyocyanin leads to ATP depletion, the mechanism of cellular metabolism of pyocyanin, and the impact of mitochondrial pyocyanin redox cycling on other cellular events are important areas for future study.
authors.affiliation: Research Service, Iowa City Veterans Affairs Medical Center, Iowa City, IA 52246, USA.
authors.forename: Yunxia Q
authors.initials: YQ
authors.lastname: O'Malley
authors.forename: Maher Y
authors.initials: MY
authors.lastname: Abdalla
authors.forename: Michael L
authors.initials: ML
authors.lastname: McCormick
authors.forename: Krzysztof J
authors.initials: KJ
authors.lastname: Reszka
authors.forename: Gerene M
authors.initials: GM
authors.lastname: Denning
authors.forename: Bradley E
authors.initials: BE
authors.lastname: Britigan
mesh_terms: D000154:Aconitate Hydratase / Q000037:antagonists & inhibitors; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D003603:Cytotoxins / Q000378:metabolism* / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects; D004594:Electrophysiology; D004847:Epithelial Cells / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007425:Intracellular Membranes / Q000502:physiology; D008168:Lung / Q000378:metabolism* / Q000648:ultrastructure; D008928:Mitochondria / Q000502:physiology / Q000648:ultrastructure; D010084:Oxidation-Reduction; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D011710:Pyocyanine / Q000378:metabolism* / Q000494:pharmacology; D013347:Subcellular Fractions / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D003603:Cytotoxins; D013481:Superoxides; D000255:Adenosine Triphosphate; D011710:Pyocyanine; D006861:Hydrogen Peroxide; D000154:Aconitate Hydratase