Escherichia coli cytochrome c peroxidase is a respiratory oxidase that enables the use of hydrogen peroxide as a terminal electron acceptor
Escherichia coli cytochrome c peroxidase is a respiratory oxidase that enables the use of hydrogen peroxide as a terminal electron acceptor
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DOI：
10.1073/pnas.1701587114
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发表时间：
2017-08-15
影响因子：
11.1
通讯作者：
Imlay, James A.
中科院分区：
文献类型：
--
作者：
Khademian, Maryam;Imlay, James A.
微生物细胞色素c过氧化物酶（Ccp）的研究已有75年的历史，但其生理功能尚不清楚。ccp位于细菌的细胞膜和真菌的线粒体膜间隙。在这项研究中，Ccp被证明是一个显着的降解过氧化氢在缺氧大肠杆菌。有趣的是，ccp转录需要H2 O2的存在和O-2的缺乏。实验表明，Ccp缺乏足够的活性来保护细胞质免受外源H2 O2的影响。然而，它从醌池接收电子，其通量率接近于流向其他厌氧电子受体。事实上，Ccp使E.大肠杆菌在非发酵性碳源上生长的最佳条件为H2 O2。沙门氏菌的表现也类似。这一作用合理化了CCP在氧化环境中的抑制作用。我们推测，微摩尔H2 O2的生物和非生物在天然好氧/缺氧界面。OxyR反应似乎利用这种H2 O2作为终端氧化剂，同时保护细胞免受其毒性。
Microbial cytochrome c peroxidases (Ccp) have been studied for 75 years, but their physiological roles are unclear. Ccps are located in the periplasms of bacteria and the mitochondrial intermembrane spaces of fungi. In this study, Ccp is demonstrated to be a significant degrader of hydrogen peroxide in anoxic Escherichia coli. Intriguingly, ccp transcription requires both the presence of H2O2 and the absence of O-2. Experiments show that Ccp lacks enough activity to shield the cytoplasm from exogenous H2O2. However, it receives electrons from the quinone pool, and its flux rate approximates flow to other anaerobic electron acceptors. Indeed, Ccp enabled E. coli to grow on a nonfermentable carbon source when H2O2 was supplied. Salmonella behaved similarly. This role rationalizes ccp repression in oxic environments. We speculate that micromolar H2O2 is created both biologically and abiotically at natural oxic/anoxic interfaces. The OxyR response appears to exploit this H2O2 as a terminal oxidant while simultaneously defending the cell against its toxicity.