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Title: Pseudomonas aeruginosa Thiol Peroxidase Protects against Hydrogen Peroxide Toxicity and Displays Atypical Patterns of Gene Regulation
Authors: Nawarat Somprasong
Thichakorn Jittawuttipoka
Jintana Duang-Nkern
Adisak Romsang
Pimchai Chaiyen
Herbert P. Schweizer
Paiboon Vattanaviboon
Skorn Mongkolsuk
Chulabhorn Research Institute
Mahidol University
Colorado State University
South Carolina Commission on Higher Education
Keywords: Biochemistry, Genetics and Molecular Biology;Immunology and Microbiology
Issue Date: 1-Aug-2012
Citation: Journal of Bacteriology. Vol.194, No.15 (2012), 3904-3912
Abstract: The Pseudomonas aeruginosa PAO1 thiol peroxidase homolog (Tpx) belongs to a family of enzymes implicated in the removal of toxic peroxides. We have shown the expression of tpx to be highly inducible with redox cycling/superoxide generators and diamide and weakly inducible with organic hydroperoxides and hydrogen peroxide (H 2 O 2 ). The PAO1 tpx pattern is unlike the patterns for other peroxide-scavenging genes in P. aeruginosa. Analysis of the tpx promoter reveals the presence of a putative IscR binding site located near the promoter. The tpx expression profiles in PAO1 and the iscR mutant, together with results from gel mobility shift assays showing that purified IscR specifically binds the tpx promoter, support the role of IscR as a transcriptional repressor of tpx that also regulates the oxidant-inducible expression of the gene. ecombinant Tpx has been purified and biochemically characterized. The enzyme catalyzes thioredoxin-dependent peroxidation and can utilize organic hydroperoxides and H 2 O 2 as substrates. The Δtpx mutant demonstrates differential sensitivity to H 2 O 2 only at moderate concentrations (0.5 mM) and not at high (20 mM) concentrations, suggesting a novel protective role of tpx against H 2 O 2 in P. aeruginosa. Altogether, P. aeruginosa tpx is a novel member of the IscR regulon and plays a primary role in protecting the bacteria from submillimolar concentrations of H 2 O 2 . © 2012, American Society for Microbiology.
ISSN: 10985530
Appears in Collections:Scopus 2011-2015

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