Wang Ge, Alamuri Praveen, Maier Robert J
Department of Microbiology, University of Georgia, Athens, GA 30602, USA.
Mol Microbiol. 2006 Aug;61(4):847-60. doi: 10.1111/j.1365-2958.2006.05302.x.
The gastric pathogen Helicobacter pylori induces a strong inflammatory host response, yet the bacterium maintains long-term persistence in the host. H. pylori combats oxidative stress via a battery of diverse activities, some of which are unique or newly described. In addition to using the well-studied bacterial oxidative stress resistance enzymes superoxide dismutase and catalase, H. pylori depends on a family of peroxiredoxins (alkylhydroperoxide reductase, bacterioferritin co-migratory protein and a thiol-peroxidase) that function to detoxify organic peroxides. Newly described antioxidant proteins include a soluble NADPH quinone reductase (MdaB) and an iron sequestering protein (NapA) that has dual roles - host inflammation stimulation and minimizing reactive oxygen species production within H. pylori. An H. pylori arginase attenuates host inflammation, a thioredoxin required as a reductant for many oxidative stress enzymes is also a chaperon, and some novel properties of KatA and AhpC were discovered. To repair oxidative DNA damage, H. pylori uses an endonuclease (Nth), DNA recombination pathways and a newly described type of bacterial MutS2 that specifically recognizes 8-oxoguanine. A methionine sulphoxide reductase (Msr) plays a role in reducing the overall oxidized protein content of the cell, although it specifically targets oxidized Met residues. H. pylori possess few stress regulator proteins, but the key roles of a ferric uptake regulator (Fur) and a post-transcriptional regulator CsrA in antioxidant protein expression are described. The roles of all of these antioxidant systems have been addressed by a targeted mutant analysis approach and almost all are shown to be important in host colonization. The described antioxidant systems in H. pylori are expected to be relevant to many bacterial-associated diseases, as genes for most of the enzymes carrying out the newly described roles are present in a number of pathogenic bacteria.
胃部病原体幽门螺杆菌会引发强烈的宿主炎症反应，但该细菌却能在宿主体内长期存活。幽门螺杆菌通过一系列不同的活动来对抗氧化应激，其中一些活动是独特的或新发现的。除了利用经过充分研究的细菌抗氧化应激酶超氧化物歧化酶和过氧化氢酶外，幽门螺杆菌还依赖于一族过氧化物酶（烷基过氧化氢还原酶、细菌铁蛋白共迁移蛋白和一种硫醇过氧化物酶），这些酶的作用是清除有机过氧化物。新发现的抗氧化蛋白包括一种可溶性NADPH醌还原酶（MdaB）和一种具有双重作用的铁螯合蛋白（NapA）——刺激宿主炎症以及减少幽门螺杆菌内活性氧的产生。幽门螺杆菌的一种精氨酸酶可减轻宿主炎症，一种作为许多氧化应激酶还原剂所需的硫氧还蛋白也是一种伴侣蛋白，并且还发现了KatA和AhpC的一些新特性。为修复氧化性DNA损伤，幽门螺杆菌利用一种核酸内切酶（Nth）、DNA重组途径以及一种新发现的能特异性识别8-氧鸟嘌呤的细菌MutS2类型。一种甲硫氨酸亚砜还原酶（Msr）在降低细胞整体氧化蛋白含量方面发挥作用，尽管它专门针对氧化的甲硫氨酸残基。幽门螺杆菌拥有很少的应激调节蛋白，但描述了铁摄取调节蛋白（Fur）和转录后调节蛋白CsrA在抗氧化蛋白表达中的关键作用。所有这些抗氧化系统的作用都已通过靶向突变分析方法进行了研究，并且几乎所有系统都显示在宿主定殖中很重要。幽门螺杆菌中所描述的抗氧化系统预计与许多细菌相关疾病有关，因为执行新发现功能的大多数酶的基因存在于许多致病细菌中。
