A dynamic periplasmic electron transfer network enables respiratory flexibility beyond a thermodynamic regulatory regime
A dynamic periplasmic electron transfer network enables respiratory flexibility beyond a thermodynamic regulatory regime
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DOI：
10.1038/ismej.2014.264
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发表时间：
2015-08-01
期刊：
影响因子：
11
通讯作者：
Gescher, Johannes
中科院分区：
文献类型：
--
作者：
Sturm, Gunnar;Richter, Katrin;Gescher, Johannes
微生物在能量代谢方面表现出惊人的多样性。它们可以使用各种不同的分解代谢电子受体，但它们根据热力学等级使用它们，这是由可用电子受体的氧化还原电位决定的。这种层次结构反映了一个监管机制，导致呼吸链的生产依赖于相应的电子受体的可用性。在这项研究中，我们表明，γ-变形杆菌希瓦氏oneidensis同时产生几个功能的电子传递链。此外，这些链是相互连接的，最有可能是在c型细胞色素的帮助下。单个S. oneidensis细胞由ca. 700 000血红素，这是减少在电子受体的情况下，但可以在各种电子受体的存在下，无论先前的生长条件下被再氧化。小的四血红素细胞色素（STC）和可溶性血红素和黄素含有富马酸还原酶FccA有重叠的活动，似乎是这个电子转移网络的重要。双缺失突变体表现出延迟增长或没有增长与三价铁，硝酸盐，二甲基亚砜或富马酸盐作为电子受体。我们建议，一个电子转移机制，无论产生的热力学层次，不仅使生物体能够快速释放分解代谢的电子到各种环境中的电子受体，但也提供了一个健身的好处，在氧化还原分层的环境。
Microorganisms show an astonishing versatility in energy metabolism. They can use a variety of different catabolic electron acceptors, but they use them according to a thermodynamic hierarchy, which is determined by the redox potential of the available electron acceptors. This hierarchy is reflected by a regulatory machinery that leads to the production of respiratory chains in dependence of the availability of the corresponding electron acceptors. In this study, we showed that the gamma-proteobacterium Shewanella oneidensis produces several functional electron transfer chains simultaneously. Furthermore, these chains are interconnected, most likely with the aid of c-type cytochromes. The cytochrome pool of a single S. oneidensis cell consists of ca. 700 000 hemes, which are reduced in the absence on an electron acceptor, but can be reoxidized in the presence of a variety of electron acceptors, irrespective of prior growth conditions. The small tetraheme cytochrome (STC) and the soluble heme and flavin containing fumarate reductase FccA have overlapping activity and appear to be important for this electron transfer network. Double deletion mutants showed either delayed growth or no growth with ferric iron, nitrate, dimethyl sulfoxide or fumarate as electron acceptor. We propose that an electron transfer machinery that is produced irrespective of a thermodynamic hierarchy not only enables the organism to quickly release catabolic electrons to a variety of environmental electron acceptors, but also offers a fitness benefit in redox-stratified environments.