MOLECULAR ARCHITECTURE OF UQH2: CYTC2 OXIDOREDUCTASE

UQH2 的分子结构：CYTC2 氧化还原酶

• 批准号: 6043557
• 负责人: ANTONY R. CROFTS
• 金额: $ 28.69万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6043557
• 关键词: NADPH cytochrome c2 reductase; Rhodospirillales; X ray crystallography; active sites; bioenergetics; circular dichroism; cytochrome b; dimer; electron spin resonance spectroscopy; electron transport; enzyme activity; enzyme complex; enzyme inhibitors; enzyme mechanism; enzyme structure; enzyme substrate complex; hydroquinones; iron sulfur protein; photosynthesis; photosynthetic bacteria; protein structure function; site directed mutagenesis; structural biology; ubiquinone; ultracentrifugation

The enzymes of the bc1 complex family (ubiquinol:cytochrome c oxidoreductases, and the closely related b6f complex of oxygenic photosynthesis), carry the energy flux of the biosphere, serving as the central enzymes of respiratory and photosynthetic electron transfer chains. The aim of this project has been to understand how these important enzymes function. X-ray crystallographic structures for several mitochondrial complexes have recently been solved in collaboration with Dr. Ed Berry, and an extensive analysis in the light of previous work has provide new insights on function. Much biophysical work has established the basic mechanism, and the focus in recent years has been on putting this into a structural context. The complexes catalyze the oxidation of ubiquinol and the reduction of cytochrome c through a modified Q-cycle. Three catalytic subunits, a cytochrome b with two hemes, cytochrome c1 and an iron sulfur protein, house the mechanism. These are well conserved across the bacterial/mitochondrial divide. Two separate internal electron transfer chains connect three catalytic sites that catalyze oxidation and reduction of the quinone pool, and reduction of cytochrome c. Electron transfer across the membrane, and coupling of these redox reactions to the release or uptake of protons, allows the complex to generate the transmembrane gradient that drives ATP synthesis. From our analysis of the structure, we have suggested some novel extensions of this basic mechanism, including a dramatic movement of the iron sulfur protein between its two reaction partners, a revised mechanism for the reaction by which quinol is oxidized, and a more detailed understanding of the quinone reduction site. In the renewal period, we will make use of the structure in an extended exploration of the molecular mechanism, using spectroscopic methods, and biophysical, molecular engineering and biochemical protocols developed under the grant. Apart from its intrinsic interest, the bc1 complex is a major site of production of oxygen radicals, which cause cell aging and DNA damage leading to cancer, and also the locus of inherited genetic diseases. Natural inhibitors block turnover by mimicking quinone at the catalytic sites, and commercial interest has centered on the possibility of using these as green pesticides.

bc 1复合物家族的酶（泛醇：细胞色素c氧化还原酶，以及与有氧光合作用密切相关的b6 f复合物）携带生物圈的能量通量，作为呼吸和光合电子传递链的中心酶。 该项目的目的是了解这些重要的酶是如何发挥作用的。 最近与艾德·贝瑞博士合作解决了几种线粒体复合物的X射线晶体学结构，根据以前的工作进行了广泛的分析，为功能提供了新的见解。 许多生物物理学工作已经确立了基本机制，近年来的重点是将其置于结构背景下。 该配合物通过修饰的Q-循环催化泛醇的氧化和细胞色素c的还原。 三个催化亚基，细胞色素B与两个血红素，细胞色素c1和铁硫蛋白，房子的机制。 这些在细菌/线粒体分裂中很好地保守。 两个独立的内部电子转移链连接三个催化位点，催化醌池的氧化和还原，以及细胞色素c的还原。 跨膜的电子转移，以及这些氧化还原反应与质子的释放或摄取的耦合，允许复合物产生驱动ATP合成的跨膜梯度。 从我们的结构分析，我们提出了一些新的扩展，这一基本机制，包括一个戏剧性的运动的铁硫蛋白之间的两个反应伙伴，修订的反应机制，其中醌被氧化，和更详细的了解醌还原位点。 在更新期间，我们将利用光谱方法，生物物理，分子工程和生物化学协议开发的资助下，在分子机制的扩展探索中使用的结构。 除了其内在的利益，bc 1复合物是氧自由基的主要生产场所，导致细胞老化和DNA损伤导致癌症，也是遗传性遗传疾病的位点。天然抑制剂通过在催化位点模拟醌来阻断周转，商业兴趣集中在将这些用作绿色农药的可能性上。