Bioenergetics and anaerobic respiratory chains of aceticlastic methanogens.
Bioenergetics and anaerobic respiratory chains of aceticlastic methanogens.
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DOI：
10.1016/j.bbabio.2013.12.002
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发表时间：
2014-07
期刊：
影响因子：
--
通讯作者：
C. Welte;U. Deppenmeier
中科院分区：
文献类型：
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作者：
C. Welte;U. Deppenmeier
产生甲烷的古细菌是严格意义上的厌氧微生物，对全球碳通量至关重要，因为它们在缺氧的情况下完成有机物分解的最后一步。自然界产生的甲烷大部分来自醋酸酯的甲基。只有甲烷菌属和甲烷菌属的成员能够利用这种底物形成和生长甲烷。由于醋酸酯产甲烷的自由能变化仅为- 36 kJ/mol CH4，因此醋酸酯产甲烷者开发了高效的节能系统来应对这一热力学限制。醋酸化产甲烷菌的膜结合电子传递系统是一个复杂的支链呼吸链，可以接受来自氢、还原性辅酶f420或还原性铁氧还蛋白的电子。这种厌氧呼吸的末端电子受体是由辅酶M和辅酶b组成的混合二硫化物。还原铁氧还蛋白在醋酸生长条件下具有重要的功能，我们将深入讨论氧化铁氧还蛋白的新型和成熟的膜复合物。膜结合电子传递是通过质子或钠离子转移酶（f420h2脱氢酶、Rnf复合物、Ech氢化酶、甲基吩肼还原氢化酶和异二硫还原酶）来实现能量守恒的。由此产生的电化学离子梯度构成了三磷酸腺苷合成的驱动力。本文讨论了产甲烷菌的产生、电子传递和关键酶的结构，从而对醋酸产甲烷菌如何谋生有了一个概念。这篇文章是第18届欧洲生物能源会议特刊的一部分。
Methane-forming archaea are strictly anaerobic microbes and are essential for global carbon fluxes since they perform the terminal step in breakdown of organic matter in the absence of oxygen. Major part of methane produced in nature derives from the methyl group of acetate. Only members of the generaMethanosarcinaandMethanosaetaare able to use this substrate for methane formation and growth. Since the free energy change coupled to methanogenesis from acetate is only − 36 kJ/mol CH4, aceticlastic methanogens developed efficient energy-conserving systems to handle this thermodynamic limitation. The membrane bound electron transport system of aceticlastic methanogens is a complex branched respiratory chain that can accept electrons from hydrogen, reduced coenzyme F420or reduced ferredoxin. The terminal electron acceptor of this anaerobic respiration is a mixed disulfide composed of coenzyme M and coenzyme B. Reduced ferredoxin has an important function under aceticlastic growth conditions and novel and well-established membrane complexes oxidizing ferredoxin will be discussed in depth. Membrane bound electron transport is connected to energy conservation by proton or sodium ion translocating enzymes (F420H2dehydrogenase, Rnf complex, Ech hydrogenase, methanophenazine-reducing hydrogenase and heterodisulfide reductase). The resulting electrochemical ion gradient constitutes the driving force for adenosine triphosphate synthesis. Methanogenesis, electron transport, and the structure of key enzymes are discussed in this review leading to a concept of how aceticlastic methanogens make a living. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.