The antioxidant protein alkylhydroperoxide reductase of Heliclobacter pylori switches from a peroxide reductase to a molecular chaperone function
The antioxidant protein alkylhydroperoxide reductase of Heliclobacter pylori switches from a peroxide reductase to a molecular chaperone function
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DOI：
10.1073/pnas.0510770103
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发表时间：
2006-02-21
影响因子：
11.1
通讯作者：
Chiou, SH
中科院分区：
文献类型：
--
作者：
Chuang, MH;Wu, MS;Chiou, SH
幽门螺杆菌是一种对氧敏感的微需氧细菌，它含有多种抗氧化蛋白，其中烷基过氧化氢还原酶(AhpC)含量最高。AhpC的功能是通过还原有毒的有机过氧化氢来保护幽门螺杆菌免受高氧环境的伤害。我们发现来自幽门螺杆菌的AhpC序列与哺乳动物的过氧化还蛋白同源性高于与真细菌AhpC的同源性。我们还发现，在氧化应激下，AhpC的蛋白质结构可以从具有过氧化氢还原酶活性的低分子低聚物转变为具有分子伴侣功能的高分子量复合体。通过跟踪AhpC在体内的四级结构变化进行的时间进程研究表明，该酶在严重的长期氧化应激后，从正常微氧条件下的低聚物或短期氧化应激下的低聚物转变为高相对分子质量的复合体。本研究揭示了幽门螺杆菌AhpC在氧化应激条件下作为过氧化氢还原酶和防止蛋白质错误折叠的分子伴侣的作用。
Helicobacter pylori, an oxygen-sensitive microaerophilic bacterium, contains many antioxidant proteins, among which alkylhydroperoxide reductase (AhpC) is the most abundant. The function of AhpC is to protect H. pylori from a hyperoxidative environment by reduction of toxic organic hydroperoxides. We have found that the sequence of AhpC from H. pylori is more homologous to mammalian peroxiredoxins than to eubacterial AhpC. We have also found that the protein structure of AhpC could shift from low-molecular-weight oligomers with peroxide-reductase activity to high-molecular-weight complexes with molecular-chaperone function under oxidative stresses. Time-course study by following the quaternary structural change of AhpC in vivo revealed that this enzyme changes from low-molecular-weight oligomers under normal microaerobic conditions or short-term oxidative shock to high-molecular-weight complexes after severe long-term oxidative stress. This study revealed that AhpC of H. pylori acts as a peroxide reductase in reducing organic hydroperoxides and as a molecular chaperone for prevention of protein misfolding under oxidative stress.