Role of Subunit IV in Prokaryotic Cytochrome bc1 Complex

亚基 IV 在原核细胞色素 bc1 复合物中的作用

• 批准号: 9019570
• 负责人: Robert Niederman
• 金额: $ 17.5万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-05-01 至 1994-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9019570&HistoricalAwards=false
• 关键词: Role; Subunit; IV; Prokaryotic; Cytochrome

The ubiquinol-cytochrome c oxidoreductase (cytochrome bc1 complex) is among the most highly conserved constituents of energy transducing membranes. Although complexes from phylogenetically diverse species are functionally interchangeable and their cytochrome c1 cytochrome b and iron-sulfur protein components are homologous, isolated oxidoreductases differ markedly with respect to additional polypeptide constituents. Mitochondrial complexes contain as many as eight additional subunits which are required in the enhancement of electron transport and in the assembly process. The cytochrome bc1 complex of Rhodobacter sphaeroides contains a tightly bound forth subunit which provides sa unique opportunity to elucidate the role of a single noncatalytic component. Partial sequence data will be used to construct hybridization probes to facilitate the isolation of the subunit IV structural gene for sequence comparisons. Topological analyses in which either the cytoplasmic or the periplasmic side of the membrane is digested with proteinase K will determine the location of subunit IV to assist in elucidating its functional role. Electron transfer activity and changes in the EPR signals of the iron-sulfur and Qc components will be assessed in the purified cytochrome bc1 complex following limited proteolytic digestion and after exposure to anti-subunit IV antibodies. Mutants in which the structural gene for subunit IV has been interrupted by interposon mutagenesis will be constructed and the composition and functional properties of the altered complex will be examined. These integrated approaches should prove valuable in elucidating important structure-function and assembly relationships in the bc1 complex.

泛喹啉-细胞色素c氧化还原酶（细胞色素bc 1 复合物）是最高度保守的成分之一， 能量转换膜。 虽然复合物从 基因多样性物种在功能上 它们细胞色素c1、细胞色素B和 铁硫蛋白组分是同源的，分离的， 氧化还原酶与其他酶有显著不同， 多肽成分 线粒体复合体含有 需要多达八个额外的子单元， 增强电子传输和组装 过程 红细菌的细胞色素bc 1复合物 sphaeroides含有一个紧密结合的前亚基， 提供了一个独特的机会来阐明一个 单一非催化组分。 部分序列数据将 用于构建杂交探针，以促进 分离亚基IV结构基因用于测序 比较。 拓扑分析，其中 细胞质或膜的周质侧， 用蛋白酶K消化将确定 亚基IV，以帮助阐明其功能作用。 电子转移活性和EPR信号的变化 铁硫和Qc成分将在 纯化的细胞色素bc 1复合物， 消化和暴露于抗亚单位IV抗体后。 其中亚基IV的结构基因已被 将构建被插入子诱变中断的 改变的组织的组成和功能特性 复杂的将被检查。 这些综合办法应 在阐明重要的结构-功能方面证明是有价值的 以及BC 1复合体中的组装关系。