Cytochrome bc1 complexes of microorganisms.
Cytochrome bc1 complexes of microorganisms.
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DOI：
10.1128/mmbr.54.2.101-129.1990
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发表时间：
1990-06
期刊：
影响因子：
--
通讯作者：
B. Trumpower
中科院分区：
文献类型：
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作者：
B. Trumpower
细胞色素bc 1复合物是最广泛存在的能够进行能量转导的电子转移复合物。细胞色素bc 1复合物存在于遗传多样的光合和呼吸细菌的质膜中，以及所有真核细胞的线粒体内膜中。在所有这些物种中，bc 1复合物将电子从低电位的醌醇转移到高电位的c型细胞色素，并将这种电子转移与质子转移联系起来。大多数细菌也具有能够绕过bc 1复合物的对苯二酚氧化的替代途径，但这些途径通常缺乏bc 1复合物的能量转换和质子转移活性。所有的细胞色素bc 1复合物含有三个电子转移蛋白，其中含有四个氧化还原辅基。它们是细胞色素B，其中含有两个B血红素基团，其光学和热力学性质不同;细胞色素c1，其中含有共价结合的c型血红素;和2Fe-2S铁硫蛋白。连接质子易位的电子转移通过这些蛋白质的机制是质子动力Q循环，这种机制似乎是普遍的所有bc 1复合物。实验目前集中在理解这些氧化还原蛋白参与Q-循环机制的先决条件选择的结构-功能关系。线粒体的细胞色素bc 1复合物与细菌的不同之处在于，前者除了细菌和线粒体共有的三种氧化还原蛋白外，还含有六到八种额外的多肽。这些额外的多肽在细胞核中编码，不含氧化还原辅基。线粒体bc 1复合物的额外多肽的功能通常是未知的，并正在积极探索通过遗传操纵这些蛋白质在酿酒酵母。
The cytochrome bc1 complex is the most widely occurring electron transfer complex capable of energy transduction. Cytochrome bc1 complexes are found in the plasma membranes of phylogenetically diverse photosynthetic and respiring bacteria, and in the inner mitochondrial membrane of all eucaryotic cells. In all of these species the bc1 complex transfers electrons from a low-potential quinol to a higher-potential c-type cytochrome and links this electron transfer to proton translocation. Most bacteria also possess alternative pathways of quinol oxidation capable of circumventing the bc1 complex, but these pathways generally lack the energy-transducing, protontranslocating activity of the bc1 complex. All cytochrome bc1 complexes contain three electron transfer proteins which contain four redox prosthetic groups. These are cytochrome b, which contains two b heme groups that differ in their optical and thermodynamic properties; cytochrome c1, which contains a covalently bound c-type heme; and a 2Fe-2S iron-sulfur protein. The mechanism which links proton translocation to electron transfer through these proteins is the proton motive Q cycle, and this mechanism appears to be universal to all bc1 complexes. Experimentation is currently focused on understanding selected structure-function relationships prerequisite for these redox proteins to participate in the Q-cycle mechanism. The cytochrome bc1 complexes of mitochondria differ from those of bacteria, in that the former contain six to eight supernumerary polypeptides, in addition to the three redox proteins common to bacteria and mitochondria. These extra polypeptides are encoded in the nucleus and do not contain redox prosthetic groups. The functions of the supernumerary polypeptides of the mitochondrial bc1 complexes are generally not known and are being actively explored by genetically manipulating these proteins in Saccharomyces cerevisiae.