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首页> 外文期刊>Journal of bacteriology >Overlapping and Complementary Oxidative Stress Defense Mechanisms in Nontypeable Haemophilus influenzae
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Overlapping and Complementary Oxidative Stress Defense Mechanisms in Nontypeable Haemophilus influenzae

机译：非分型流感嗜血杆菌的重叠和互补氧化应激防御机制

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The Gram-negative commensal bacterium nontypeable Haemophilus influenzae (NTHI) can cause respiratory tract diseases that include otitis media, sinusitis, exacerbations of chronic obstructive pulmonary disease, and bronchitis. During colonization and infection, NTHI withstands oxidative stress generated by reactive oxygen species produced endogenously, by the host, and by other copathogens and flora. These reactive oxygen species include superoxide, hydrogen peroxide (H2O2), and hydroxyl radicals, whose killing is amplified by iron via the Fenton reaction. We previously identified genes that encode proteins with putative roles in protection of the NTHI isolate strain 86-028NP against oxidative stress. These include catalase (HktE), peroxiredoxin/glutaredoxin (PgdX), and a ferritin-like protein (Dps). Strains were generated with mutations in hktE, pgdX, and dps. The hktE mutant and a pgdX hktE double mutant were more sensitive than the parent to killing by H2O2. Conversely, the pgdX mutant was more resistant to H2O2 due to increased catalase activity. Supporting the role of killing via the Fenton reaction, binding of iron by Dps significantly mitigated the effect of H2O2-mediated killing. NTHI thus utilizes several effectors to resist oxidative stress, and regulation of free iron is critical to this protection. These mechanisms will be important for successful colonization and infection by this opportunistic human pathogen.
机译：革兰氏阴性共生细菌不可分型的流感嗜血杆菌（NTHI）可以引起呼吸道疾病，包括中耳炎，鼻窦炎，慢性阻塞性肺疾病加重和支气管炎。在定植和感染过程中，NTHI可承受由内源性，宿主以及其他同病原体和菌群内源性产生的活性氧所产生的氧化应激。这些活性氧包括超氧化物，过氧化氢（H 2 O 2 ）和羟基自由基，它们的杀灭作用通过Fenton反应被铁放大。我们先前确定了编码蛋白质的基因，这些蛋白质在保护NTHI分离株86-028NP抵抗氧化应激中具有假定的作用。这些包括过氧化氢酶（HktE），过氧化物酶/谷氨酰胺酶（PgdX）和铁蛋白样蛋白（Dps）。菌株在 hktE ， pgdX 和 dps 中发生突变。 hktE 突变体和 pgdX hktE 双重突变体对H 2 O 2 的杀灭作用比亲本更为敏感。 。相反，由于过氧化氢酶活性的增加， pgdX 突变体对H 2 O 2 的抵抗力更高。支持通过芬顿反应的杀伤作用，Dps与铁的结合显着减轻了H 2 O 2 介导的杀伤作用。因此，NTHI利用多种效应子抵抗氧化应激，因此游离铁的调节对于这种保护至关重要。这些机制对于这种机会性人类病原体的成功定殖和感染非常重要。

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