MECHANISM OF RESPIRATION AND ENERGY TRANSDUCTION

这个项目的目的是阐明电子的作用机制。 细胞色素Bc1复合体中的转移和质子转移 线粒体呼吸链。现有证据表明 通过细胞色素Bc1复合体的电子转移是通过质子动力Q进行的 循环机制。我们特别感兴趣的是定义这两个 泛喹酚氧化还原位(Q循环术语中的“中心O和中心I”)，以及 在确定Bc1复合体的非氧化还原蛋白的功能方面。我们 正在利用分子遗传学和膜生物化学来解决这些问题 酿酒酵母中的问题。 在目前的项目期间，我们的具体目标包括寻找一个 Rieske铁硫团簇上推测的泛喹酚氧化点。在……里面 此外，我们计划确定Rieske铁硫蛋白的区域 它们与细胞色素b的蛋白结构域一起形成泛喹酚。 氧化位置在O中心。 鉴定可能与泛醌还原有关的多肽 在中心I，我们计划研究14 kDa亚基7和14 kDa亚基的作用 稳定乌双喹酮的11 kDa亚基8。我们还计划 确定相互作用的14 kDa和11 kDa亚基的界面 含细胞色素b 我们将检测7.3 kDa亚基9和酸性17 kDa亚基6 可以在当前的某些情况下调节复合体的活性或组装 无法辨认的方式。这两个“多余的”多肽， 为真核细胞色素Bc1复合体所特有，没有明显的 电子转移或质子转移中的必备功能 线粒体Bc1复合体的活性。的可能功能 这些蛋白质将在酵母菌株中进行测试，这些酵母菌株的基因 这些蛋白已经被删除，或者野生型基因已经被删除 取而代之的是体外产生的突变体。

The objective of this project is to elucidate the mechanism of electron transfer and proton translocation in the cytochrome bc1 complex of the mitochondrial respiratory chain. Available evidence indicates that electron transfer through the cytochrome bc1 complex is by a protonmotive Q cycle mechanism. We are particularily interested in defining the two ubiquinol redox sites ("center o and center i" in Q cycle terminology), and in establishing the functions of non-redox proteins of the bc1 complex. We are using molecular genetics and membrane biochemistry to address these questions in saccharomyces cerevisiae. During the current project period our specific aims include locating a putative ubiquinol oxidation site on the Rieske iron-sulfur cluster. In addition, we plan to identify the regions of the Rieske iron-sulfur protein which, together with protein domains from cytochrome b, form the ubiquinol oxidizing site at center o. To identify polypeptides possibly contributing to the ubiquinone reducing site at center i, we plan to examine the roles of the 14 kDa subunit 7 and the 11 kDa subunit 8 in stabilizing ubisemiquinone. We also plan to identify the interfaces of the 14 kDa and 11 kDa subunits which interact with cytochrome b We will test whether the 7.3 kDa subunit 9 and the acidic 17 kDa subunit 6 may modulate the activity or assembly of the complex in some currently unrecognized manner. These two "supernumerary" polypeptides, which appear to be unique to eukaryotic cytochrome bc1 complexes, have no obvious obligatory function in the electron transfer or proton translocation activities of the mitochondrial bc1 complex. The possible functions of these proteins will be tested in yeast strains from which the genes for these proteins have been deleted, or in which the wild type genes have been replaced by mutants generated in vitro.