Structure of reaction intermediates in the bc1 complex

bc1配合物中反应中间体的结构

基本信息

批准号：
7666687
负责人：
SERGEI A DIKANOV
金额：
$ 26.11万
依托单位：
UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-03-01 至 2011-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7666687
关键词：
Acquired Immunodeficiency Syndrome Address Affect Aging Aging-Related Process Agrochemicals Apoptosis Asphyxia Bacteria Behavior Binding Biochemical Biological Models Catalysis Catalytic Domain Cell Nucleus Cessation of life Characteristics Chemistry Complex Correlation Studies Cysteine Cytochrome bc1 Complex Cytochrome c1 Cytochromes Cytochromes b DNA Data Defect Development Disputes Drug Delivery Systems Electron Nuclear Double Resonance Electron Spin Resonance Spectroscopy Electron Transport Electrons Elements Energy Metabolism Engineering Environment Enzymes Equipment and supply inventories Family Freezing Funding Generations Heme Herbicides Histidine Housing Hydrogen Bonding Hydroquinones In Vitro Industrial fungicide Industry Investigation Ions Iron-Sulfur Proteins Ischemia Isotope Labeling Isotopes Kinetics Label Lead Ligands Ligation Link Lipids Magnetism Malaria Maps Mediating Medical Membrane Membrane Proteins Mitochondria Mitochondrial DNA Mitochondrial Myopathies Modeling Modification Molecular Mutation Neighborhoods Nitrogen Nuclear Oxidation-Reduction Oxis Parasites Pathology Pathway interactions Pesticides Phase Photosynthesis Physiologic pulse Physiological Plasmodium Play Pneumocystis carinii Positioning Attribute Production Property Proteins Protocols documentation Proton Pump Protons Qi Quinone Reductases Quinones Reaction Reactive Oxygen Species Reagent Recovery Regulation Relative (related person)Research Research Personnel Resolution Respiratory Chain Rieske iron-sulfur protein Role Side Site Solvents Spectrum Analysis Stress Structure Sulfur Superoxides Techniques Therapeutic Agents Thermodynamics Tissues Toxoplasmosis Ubiquinone Work aqueous base comparative density design electronic structure enzyme substrate fungus inhibitor/antagonist insight interest ionization killings mutant oxidation programs protein structure receptor research study secondary infection semiquinone theories tool ubisemiquinone uptake

项目摘要

DESCRIPTION (provided by applicant): In this proposal we will use high-resolution EPR spectroscopy to explore the catalytic domains of the bc1 complex trapped in states with paramagnetic intermediates bound. The cytochrome bc1 complex family plays an essential role in the energy metabolism of the biosphere. Three catalytic subunits, cyt b, cyt c1 and the Rieske iron sulfur protein (ISP), house the mechanism. Two catalytic sites in cyt b are involved in oxi-dation or reduction of ubiquinone. The integration of the oxidation and reduction reactions with the release or uptake of protons in the aqueous phases, allows the complex to pump protons across the membrane. To understand the mechanism, we need detailed information about the local reaction environment, including protein structure, hydrogen bonding, and distances, to provide the parameters that control rates, and partitioning of electrons to different pathways. Several partial reactions in the bc1 complex involve paramagnetic intermediates. The EPR approach is well suited to dissecting these, because pulsed-EPR techniques can probe interactions between the electron spin of the intermediate and local magnetic nuclei. They thus pro- vide direct information about spatial and electronic structure of the intermediate and the immediate protein and solvent environment. The species at the focus of the proposal are the reduced [2Fe-2S] cluster of the ISP participating in ubihydroquinone (quinol, QH2) oxidation at the Qo-site; and the semiquinone (SQ) involved in the reactions of the quinone-reducing Qi-site. The choreography of catalysis at these sites is largely controlled by the changes in local configuration needed to accommodate the binding requirements of the different quinone forms, and EPR of the SQ provides a direct tool. This work will be pursued in the context of separately funded studies of kinetic and mechanistic aspects, and an extensive inventory of biophysical, biochemical, and molecular engineering protocols allowing us to correlate data for paramagnetic species, and functional and structural changes in mutant strains. The main question to be addressed is that of how the protein environment modifies the spatial and electronic structure of the intermediates to fit the physiological function, a question of much wider interest in reaction mechanism theory. The central role of bc1 complex plays out in many medical scenarios in which defects lead to pathology, among them cellular death through ROS-mediated damage, mitochondrial myopathies, and apoptosis, and in drug targeting.

描述（由申请人提供）：在本提案中，我们将使用高分辨率 EPR 光谱来探索 bc1 复合物在顺磁性中间体束缚状态下的催化域。细胞色素 bc1 复合物家族在生物圈的能量代谢中发挥着重要作用。该机制由三个催化亚基 cyt b、cyt c1 和 Rieske 铁硫蛋白 (ISP) 负责。 cyt b 中的两个催化位点参与泛醌的氧化或还原。氧化和还原反应与水相中质子的释放或吸收相结合，使得复合物能够将质子泵过膜。为了理解这一机制，我们需要有关局部反应环境的详细信息，包括蛋白质结构、氢键和距离，以提供控制速率和电子分配到不同路径的参数。 bc1 配合物中的几个部分反应涉及顺磁性中间体。 EPR 方法非常适合剖析这些问题，因为脉冲 EPR 技术可以探测中间磁核和局部磁核的电子自旋之间的相互作用。因此，它们提供了有关中间体以及直接蛋白质和溶剂环境的空间和电子结构的直接信息。该提案的重点物种是 ISP 的还原 [2Fe-2S] 簇，参与 Qo 位点的泛氢醌（对苯二酚，QH2）氧化；和半醌（SQ）参与醌还原Qi位的反应。这些位点的催化编排很大程度上是通过适应不同醌形式的结合要求所需的局部构型的变化来控制的，而 SQ 的 EPR 提供了一个直接的工具。这项工作将在单独资助的动力学和机械方面的研究以及生物物理、生物化学和分子工程方案的广泛库存的背景下进行，使我们能够将顺磁物种的数据以及突变株的功能和结构变化关联起来。要解决的主要问题是蛋白质环境如何改变中间体的空间和电子结构以适应生理功能，这是反应机制理论中更广泛关注的问题。 bc1 复合物在许多缺陷导致病理的医学场景中发挥着核心作用，其中包括通过 ROS 介导的损伤导致的细胞死亡、线粒体肌病和细胞凋亡，以及药物靶向。