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首页> 外文期刊>Journal of bacteriology >Pseudomonas aeruginosa Thiol Peroxidase Protects against Hydrogen Peroxide Toxicity and Displays Atypical Patterns of Gene Regulation
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Pseudomonas aeruginosa Thiol Peroxidase Protects against Hydrogen Peroxide Toxicity and Displays Atypical Patterns of Gene Regulation

机译:铜绿假单胞菌硫醇过氧化物酶可防止过氧化氢的毒性并显示基因调控的非典型模式

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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 (H2O2). 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. Recombinant Tpx has been purified and biochemically characterized. The enzyme catalyzes thioredoxin-dependent peroxidation and can utilize organic hydroperoxides and H2O2 as substrates. The Δtpx mutant demonstrates differential sensitivity to H2O2 only at moderate concentrations (0.5 mM) and not at high (20 mM) concentrations, suggesting a novel protective role of tpx against H2O2 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 H2O2.
机译:铜绿假单胞菌PAO1硫醇过氧化物酶同源物(Tpx)属于涉及清除有毒过氧化物的酶家族。我们已经显示, tpx 的表达在氧化还原循环/超氧化物产生剂和二酰胺中是高诱导性的,在有机氢过氧化物和过氧化氢(H 2 O 2 )。 PAO1 tpx 模式不同于铜绿假单胞菌中其他清除过氧化物基因的模式。对 tpx 启动子的分析揭示了位于启动子附近的推定IscR结合位点的存在。 PAO1和 iscR 突变体中的 tpx 表达谱,以及凝胶迁移率变动分析的结果表明,纯化的IscR特异性结合了 tpx 启动子,支持IscR作为 tpx 的转录阻遏物的作用,后者还调节该基因的氧化剂诱导表达。重组Tpx已纯化并经过生化鉴定。该酶催化硫氧还蛋白依赖性的过氧化反应,可以利用有机氢过氧化物和H 2 O 2 作为底物。 Δ tpx 突变体仅在中等浓度(0.5 mM)而不对高浓度(20 mM)表现出对H 2 O 2 的敏感性差异,提示 tpx 对铜绿假单胞菌H 2 O 2 具有新的保护作用。总的来说,铜绿假单胞菌是IscR调节剂的新成员,在保护细菌免受浓度低于H 2 O 2 的毫摩尔浓度中起主要作用。

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