The aerobic respiratory chain of the acidophilic archaeon Ferroplasma acidiphilum: A membrane-bound complex oxidizing ferrous iron
The aerobic respiratory chain of the acidophilic archaeon Ferroplasma acidiphilum: A membrane-bound complex oxidizing ferrous iron
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DOI：
10.1016/j.bbabio.2015.04.006
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发表时间：
2015-08-01
影响因子：
4.3
通讯作者：
Guiral, Marianne
中科院分区：
文献类型：
--
作者：
Castelle, Cindy J.;Roger, Magali;Guiral, Marianne
极端嗜酸古细菌酸性铁浆菌是在富铁的生物采矿环境中发现的一种重要微生物，也是ADD矿井水中天然微生物群落中的重要微生物。嗜酸杆菌是一种铁氧化剂，属于热浆菌目(Eurya Chaeota)，它含有迄今已知的最极端嗜酸的微生物。目前，对影响铁的生物地球化学循环的蛋白质的性质或结构和功能组织知之甚少。在这里，我们结合生化和生物物理技术，如酶纯化、活性测量、蛋白质组学和光谱学等，对酸菲尔氏菌的铁氧化途径(S)进行了表征。我们分离到两个呼吸膜蛋白复合体：一个是850 kDa的复合体，含有一个AA(3)型细胞色素氧化酶和一个直接氧化亚铁并还原分子氧的蓝铜蛋白；另一个是150 kDa的细胞色素ba复合体，可能由一个双血红素细胞色素和一个Rieske蛋白组成。我们初步认为这两个复合体都参与了铁氧化呼吸链，在所谓的上坡和下坡电子流动途径中发挥作用，这与自养生命是一致的。细胞色素HA复合体可能通过反向(‘上坡’)电子流在再生还原当量中发挥作用。这项研究是对铁质体属嗜酸性古生菌中可能直接参与铁介导的能量守恒的金属蛋白的第一次详细的生化研究。(C)2015爱思唯尔B.V.保留所有权利。
The extremely acidophilic archaeon Ferroplasma acidiphilum is found in iron-rich biomining environments and is an important micro-organism in naturally occurring microbial communities in add mine drainage. F. acidiphilum is an iron oxidizer that belongs to the order Thermoplasmatales (Euryarchaeota), which harbors the most extremely acidophilic micro-organisms known so far. At present, little is known about the nature or the structural and functional organization of the proteins in F. acidiphilum that impact the iron biogeochemical cycle. We combine here biochemical and biophysical techniques such as enzyme purification, activity measurements, proteomics and spectroscopy to characterize the iron oxidation pathway(s) in F. acidiphilum. We isolated two respiratory membrane protein complexes: a 850 kDa complex containing an aa(3)-type cytochrome oxidase and a blue copper protein, which directly oxidizes ferrous iron and reduces molecular oxygen, and a 150 kDa cytochrome ba complex likely composed of a di-heme cytochrome and a Rieske protein. We tentatively propose that both of these complexes are involved in iron oxidation respiratory chains, functioning in the so-called uphill and downhill electron flow pathways, consistent with autotrophic life. The cytochrome ha complex could possibly play a role in regenerating reducing equivalents by a reverse ('uphill') electron flow. This study constitutes the first detailed biochemical investigation of the metalloproteins that are potentially directly involved in iron-mediated energy conservation in a member of the acidophilic archaea of the genus Ferroplasma. (C) 2015 Elsevier B.V. All rights reserved.