Energized outer membrane and spatial separation of metabolic processes in the hyperthermophilic Archaeon Ignicoccus hospitalis
Energized outer membrane and spatial separation of metabolic processes in the hyperthermophilic Archaeon Ignicoccus hospitalis
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DOI：
10.1073/pnas.0911711107
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发表时间：
2010-02-16
影响因子：
11.1
通讯作者：
Huber, Harald
中科院分区：
文献类型：
--
作者：
Kueper, Ulf;Meyer, Carolin;Huber, Harald
ATP合酶催化ATP的合成是以电化学离子梯度为代价的，而电化学离子梯度可以通过不同的出能反应产生。超嗜热严格厌氧医院火苗古菌的主要产能反应是硫还原。这种生物是不寻常的，它有一个由巨大的膜间室隔开的内膜和外膜。在这里，我们显示，基于超薄切片的免疫电镜分析和对整个I. hospitalis细胞的免疫荧光实验，该生物的ATP合酶和H-2：硫氧化还原酶复合物位于外膜。这两种酶复合物对于产生电化学梯度和ATP合成是必需的。因此，在所有包膜具有两层膜的原核生物（包括plantomycetes，革兰氏阴性菌）中，I. hospitalis是一种独特的生物，具有充满能量的外膜，并在质周空间内合成ATP。此外，DAPI染色和EM分析显示，DNA和核糖体定位于细胞质中，从而得出结论，医院的能量保存与信息处理和蛋白质生物合成分离。这就提出了关于两个膜的功能、这些隔室之间的相互作用以及细胞质膜的一般定义的问题。
ATP synthase catalyzes ATP synthesis at the expense of an electrochemical ion gradient across a membrane that can be generated by different exergonic reactions. Sulfur reduction is the main energy-yielding reaction in the hyperthermophilic strictly anaerobic Crenarchaeon Ignicoccus hospitalis. This organism is unusual in having an inner and an outer membrane that are separated by a huge intermembrane-compartment. Here we show, on the basis of immuno-EM analyses of ultrathin sections and immunofluorescence experiments with whole I. hospitalis cells, that the ATP synthase and H-2:sulfur oxidoreductase complexes of this organism are located in the outer membrane. These two enzyme complexes are mandatory for the generation of an electrochemical gradient and for ATP synthesis. Thus, among all prokaryotes possessing two membranes in their cell envelope (including Planctomycetes, Gram-negative bacteria), I. hospitalis is a unique organism, with an energized outermembrane and ATP synthesis within the periplasmic space. In addition, DAPI staining and EM analyses showed that DNA and ribosomes are localized in the cytoplasm, leading to the conclusion that in I. hospitalis energy conservation is separated from information processing and protein biosynthesis. This raises questions regarding the function of the two membranes, the interaction between these compartments, and the general definition of a cytoplasmic membrane.