A membrane-bound multienzyme, hydrogen-oxidizing, and sulfur-reducing complex from the hyperthermophilic bacterium Aquifex aeolicus
A membrane-bound multienzyme, hydrogen-oxidizing, and sulfur-reducing complex from the hyperthermophilic bacterium Aquifex aeolicus
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DOI：
10.1074/jbc.m508034200
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发表时间：
2005-12-23
影响因子：
4.8
通讯作者：
Giudici-Orticoni, MT
中科院分区：
文献类型：
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作者：
Guiral, M;Tron, P;Giudici-Orticoni, MT
Aquifex aeolicus 是一种超嗜热、化能自养、氢氧化和微需氧细菌，生长温度为 85°C。我们已经证明，它可以在 H-2/S 度培养基上生长，并在指数后期从硫中产生 H2S。具有硫还原活性（从 H-2 到 S 度的电子传输）的配合物已被纯化和表征。它是一种膜结合多蛋白复合物，含有通过醌连接的 [NiFe] 氢化酶和硫还原酶。硫还原酶由操纵子注释的 dms（二甲基亚砜还原酶）编码，我们将其重命名为 sre，由三个亚基组成。序列分析表明其属于Me2SO还原酶钼酶家族，与硫/多硫化物/硫代硫酸盐/连四硫酸盐还原酶相似。催化性能的研究清楚地表明它可以还原连四硫酸盐、硫和多硫化物，但不能还原Me2SO和硫代硫酸盐，并且NADPH提高了硫还原活性。迄今为止，这是对细菌中耦合氢氧化和硫还原的超级复合物的首次表征。 A. aeolicus 的显着特征是硫还原的细胞质定位，这与细胞质中硫球的存在一致。这种硫还原复合物与膜中的氢氧途径复合物（氢化酶 I，bc(1) 复合物）的结合表明，参与该细菌呼吸链的子复合物是超分子组织的一部分。
Aquifex aeolicus is a hyperthermophilic, chemolithoautotrophic, hydrogen-oxidizing, and microaerophilic bacterium growing at 85 degrees C. We have shown that it can grow on an H-2/S degrees medium and produce H2S from sulfur in the later exponential phase. The complex carrying the sulfur reducing activity (electron transport from H-2 to S degrees) has been purified and characterized. It is a membrane-bound multiprotein complex containing a [NiFe] hydrogenase and a sulfur reductase connected via quinones. The sulfur reductase is encoded by an operon annotated dms (dimethyl sulfoxide reductase) that we have renamed sre and is composed of three subunits. Sequence analysis showed that it belongs to the Me2SO reductase molybdoenzyme family and is similar to the sulfur/polysulfide/thiosulfate/tetrathionate reductases. The study of catalytic properties clearly demonstrated that it can reduce tetrathionate, sulfur, and polysulfide, but cannot reduce Me2SO and thiosulfate, and that NADPH increases the sulfur reducing activity. To date, this is the first characterization of a supercomplex from a bacterium that couples hydrogen oxidation and sulfur reduction. The distinctive feature in A. aeolicus is the cytoplasmic localization of the sulfur reduction, which is in accordance with the presence of sulfur globules in the cytoplasm. Association of this sulfur-reducing complex with a hydrogen-oxygen pathway complex (hydrogenase I, bc(1) complex) in the membrane suggests that subcomplexes involved in respiratory chains in this bacterium are part of supramolecular organization.