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首页> 外文期刊>Applied Microbiology >Investigation of the Electron Transport Chain to and the Catalytic Activity of the Diheme Cytochrome c Peroxidase CcpA of Shewanella oneidensis
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Investigation of the Electron Transport Chain to and the Catalytic Activity of the Diheme Cytochrome c Peroxidase CcpA of Shewanella oneidensis

机译：拟南芥中双血红素细胞色素c过氧化物酶CcpA的电子输运链及其催化活性的研究

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Bacterial diheme c -type cytochrome peroxidases (BCCPs) catalyze the periplasmic reduction of hydrogen peroxide to water. The gammaproteobacterium Shewanella oneidensis produces the peroxidase CcpA under a number of anaerobic conditions, including dissimilatory iron-reducing conditions. We wanted to understand the function of this protein in the organism and its putative connection to the electron transport chain to ferric iron. CcpA was isolated and tested for peroxidase activity, and its structural conformation was analyzed by X-ray crystallography. CcpA exhibited in vitro peroxidase activity and had a structure typical of diheme peroxidases. It was produced in almost equal amounts under anaerobic and microaerophilic conditions. With 50 mM ferric citrate and 50 μM oxygen in the growth medium, CcpA expression results in a strong selective advantage for the cell, which was detected in competitive growth experiments with wild-type and Δ ccpA mutant cells that lack the entire ccpA gene due to a markerless deletion. We were unable to reduce CcpA directly with CymA, MtrA, or FccA, which are known key players in the chain of electron transport to ferric iron and fumarate but identified the small monoheme ScyA as a mediator of electron transport between CymA and BCCP. To our knowledge, this is the first detailed description of a complete chain of electron transport to a periplasmic c -type cytochrome peroxidase. This study furthermore reports the possibility of establishing a specific electron transport chain using c -type cytochromes.
机译：细菌二血红素c型细胞色素过氧化物酶（BCCP）催化过氧化氢向水的周质还原。在许多厌氧条件下，包括异化铁还原条件，γ-变形杆菌Shewanella oneidensis产生了过氧化物酶CcpA。我们想了解这种蛋白质在生物体中的功能及其与电子传输链与三价铁的推定联系。分离CcpA并测试过氧化物酶活性，并通过X射线晶体学分析其结构构象。 CcpA表现出体外过氧化物酶活性，并具有典型的双血红素过氧化物酶的结构。它在厌氧和微需氧条件下的产量几乎相等。在生长培养基中含有50 mM柠檬酸铁和50μM氧气的情况下，CcpA表达对细胞具有很强的选择性优势，这是在野生型和ΔccpA突变细胞的竞争性生长实验中检测到的，这些细胞缺乏完整的ccpA基因，无标记的删除。我们无法直接用CymA，MtrA或FccA还原CcpA，CymA，MtrA或FccA在电子传输至三价铁和富马酸盐的链中起着关键作用，但确定了小的一元血红素ScyA是CymA与BCCP之间电子传输的媒介。据我们所知，这是电子传输至周质c型细胞色素过氧化物酶的完整链的第一个详细描述。这项研究还报告了使用c型细胞色素建立特定电子传输链的可能性。

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