Characterization of a novel type of benzene ring reductase in Geobacter metallireducens

苯甲酰辅酶A在兼性和严格意义上的厌氧菌中都是厌氧芳香族代谢的关键中间体。兼性厌氧菌利用依赖于ATP的环还原酶将苯甲酰辅酶A脱芳构化为两电子还原的环二烯酰辅酶A化合物。在严格的厌氧模式生物Gebacter metalliReducens中，苯甲酰辅酶A的脱芳构化似乎也是通过还原完成的，尽管依赖于ATP的苯甲酰辅酶A还原酶的四个结构基因缺失。相反，我们小组最近鉴定了八种迄今未知的蛋白质，它们是由苯甲酸诱导的Bamb-I基因编码的。它们包括钼蛋白和硒半胱氨酸蛋白的亚基，以及异二硫键还原酶和氢酶样蛋白，最有可能形成一个复合体。在本项目中，将首次研究严格厌氧模式生物苯环脱芳烃过程中单个组分/或推定的酶复合体的组成和功能。将应用一些生化、免疫学、光谱和电化学技术。所获得的结果应该揭示出对一种新的酶原理的见解。

Benzoyl-CoA is a key intermediate of anaerobic aromatic metabolism in both, facultatively and strictly anaerobic bacteria. Facultative anaerobes utilize an ATP-dependent ring reductase for the dearomatization of benzoyl-CoA to a two-electron reduced cyclic dienoyl-CoA compound. In the strictly anaerobic model organism Geobacter metallireducens, benzoyl-CoA dearomatization also appears to be accomplished by reduction, although the four structural genes of ATP-dependent benzoyl-CoA reductase are missing. Instead, eight so far unknown proteins, encoded by the benzoate-induced bamB-I genes, were recently identified by our group. They comprise subunits of Mo- and selenocysteine-proteins, and heterodisulfide reductases and hydrogenases-like proteins, most possibly forming a complex. In this project, the composition and function of the individual components/or the putative enzyme complex in benzene ring dearomatization of a strictly anaerobic model organism will be studied for the first time. A number of biochemical, immunological, spectroscopic and electrochemical techniques will be applied. The results obtained should reveal insights into a novel enzymatic principle.