title: Reactions of Pseudomonas aeruginosa pyocyanin with reduced glutathione.
abstract: Pseudomonas aeruginosa is the most common cause of chronic and recurrent lung infections in patients with cystic fibrosis (CF) whose sputa contain copious quantities of P. aeruginosa toxin, pyocyanin. Pyocyanin triggers tissue damage mainly by its redox cycling and induction of reactive oxygen species (ROS). The reactions between reduced glutathione (GSH) and pyocyanin were observed using absorption spectra from spectrophotometry and the reaction products analysed by nuclear magnetic resonance imaging. Pyocyanin reacted with GSH non-enzymatically at 37 degrees C resulting in the production of red-brown products, spectophotometrically visible as a 480 nm maximum absorption peak after 24 h of incubation. The reaction was concentration-dependent on reduced glutathione but not on pyocyanin. Minimizing the accessibility of oxygen to the reaction decreased its rate. The anti-oxidant enzyme catalase circumvented the reaction. Proton-NMR analysis demonstrated the persistence of the original aromatic ring and the methyl-group of pyocyanin in the red-brown products. Anti-oxidant agents having thiol groups produced similar spectophotometrically visible peaks. The presence of a previously unidentified non-enzymatic GSH-dependent metabolic pathway for pyocyanin has thus been identified. The reaction between pyocyanin and GSH is concentration-, time-, and O(2)-dependent. The formation of H(2)O(2) as an intermediate and the thiol group in GSH seem to be important in this reaction.
authors.affiliation: Centre for Education and Research on Ageing and ANZAC Research Institute, University of Sydney and Concord RG Hospital, Concord, Australia. rcheluvappa@med.usyd.edu.au
authors.forename: Rajkumar
authors.initials: R
authors.lastname: Cheluvappa
authors.forename: Ronald
authors.initials: R
authors.lastname: Shimmon
authors.forename: Michael
authors.initials: M
authors.lastname: Dawson
authors.forename: Sarah N
authors.initials: SN
authors.lastname: Hilmer
authors.forename: David G
authors.initials: DG
authors.lastname: Le Couteur
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism; D002374:Catalase / Q000494:pharmacology; D003550:Cystic Fibrosis / Q000150:complications; D005978:Glutathione / Q000737:chemistry / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011552:Pseudomonas Infections / Q000209:etiology; D011550:Pseudomonas aeruginosa / Q000378:metabolism* / Q000472:pathogenicity; D011710:Pyocyanine / Q000737:chemistry / Q000378:metabolism*; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D001427:Bacterial Toxins; D011710:Pyocyanine; D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione; D019803:Glutathione Disulfide