Biochemical studies on membrane-bound [NiDe] hydrogenases related to complex I

近年来，一组多亚基膜结合[NiFe]氢化酶与线粒体和细菌呼吸链的复合物I具有显着的序列相似性，已被确定。酶的列表包括大肠杆菌氢化酶-3和-4、来自红色红球菌的CO诱导的氢化酶和来自巴氏甲烷八叠球菌的Ech氢化酶。这些酶的特征在于五个保守的亚基，其在细菌和线粒体的呼吸链的复合体I中具有同源物。在复杂的I这些亚基被认为是必不可少的质子泵。这些氢化酶与复合物I的密切关系表明这些酶和复合物I具有共同的进化祖先。质子泵功能已被假定为这些氢化酶，但尚未得到证实。到目前为止，还没有详细的生化研究与这些氢化酶之一，分离为完整的蛋白质复合物，已进行。生化研究的目的，这将与Ech在这个项目中进行，是阐明复杂的I和这些氢化酶之间的功能相似性。

Project summary In the recent years a group of multisubunit membrane bound [NiFe] hydrogenases with significant sequence similarity to complex I of the mitochondrial and bacterial respiratory chain has been identified. The list of enzymes includes Escherichia coli hydrogenases-3 and -4, CO-induced hydrogenase from Rhodospirillum rubrum and Ech hydrogenase from Methanosarcina barkeri. These enzymes are characterized by five conserved subunits which have homologs in complex I of the respiratory chain of bacteria and mitochondria. In complex I these subunits are assumed to be essential for proton-pumping. The close relationship of these hydrogenases to complex I indicates that these enzymes and complex I have a common evolutionary ancestor. A proton-pumping function has been postulated for these hydrogenases but not yet proven. Thus far no detailed biochemical studies with one of these hydrogenases, isolated as intact protein complex, have been performed. The objectives of the biochemical studies, which will be performed with Ech in this project, are the elucidation of functional similarities between complex I and these hydrogenases.