MECHANISMS OF RESPIRATION AND ENERGY TRANSDUCTION

本项目的目的是阐明电子的作用机制 细胞色素bc1复合物中的质子转移和质子移位 线粒体呼吸链 现有证据表明， 通过细胞色素bc1复合物的电子转移是通过质子动力学Q 循环机制 我们特别感兴趣的是定义这两个 泛醇氧化还原位点（Q循环术语中的“中心o和中心i”），和 在建立BC 1复合物的非氧化还原蛋白质的功能方面。 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： Rieske铁硫簇上的推定泛醇氧化位点。 在 此外，我们计划确定Rieske铁硫蛋白的区域， 与来自细胞色素B的蛋白质结构域一起形成泛醇 中心O处的氧化位点。 为了鉴定可能有助于降低泛醌的多肽， 在中心i的位点，我们计划研究14 kDa亚基7和 稳定泛半醌的11 kDa亚基8。 我们还计划 鉴定相互作用的14 kDa和11 kDa亚基的界面 细胞色素B 我们将测试7.3 kDa亚基9和酸性17 kDa亚基6是否 可以调节复合物的活性或组装， 不承认的方式。 这两种“多余的”多肽， 是真核细胞色素bc1复合物所特有的， 在电子转移或质子转移中的强制性功能 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， 这些蛋白质已经被删除，或者其中野生型基因已经被 被体外产生的突变体取代。

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tested in yeast strains from which the genes for these proteins have been deleted, or in which the wild type genes have been replaced by mutants generated in vitro.