Structural Basis for Electron Transfer Between the BacterialReaction Center and Cytochrome c2 in Rhodobacter Sphaeroide studied by Site Directed Mutagenesis

通过定点诱变研究球形红细菌中细菌反应中心和细胞色素 c2 之间电子转移的结构基础

• 批准号: 9304782
• 负责人: Melvin Okamura
• 金额: $ 28.5万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-09-01 至 1996-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9304782&HistoricalAwards=false
• 关键词: Structural; Basis; Electron; Transfer; Between

9304782 Okamura Photosynthetic bacteria convert light energy into chemical energy by photo-induced electron transfer reactions in a pigment protein complex called the reaction center (RC). The initial charge separation within the RC is coupled to electron transfer across the membrane by electron transfer from a mobile electron carrier, cytochrome c2. Important features of the reaction between the RC and cytochrome c2 are the high rate of electron transfer and also the molecular recognition of electron transfer partners. The structural basis for these two properties will be investigated by studying the effects of mutating the following types of residues: (1) Charged residues on the RC and cytochrome will be modified to investigate electrostatic interactions between the two redox partners. Complementary charge changes on the RC (negative to positive charged residues) and cytochrome (negative to positive charged residues) will be made to map out the specific ion pairing interactions in the cytochrome RC complex. (2) Uncharged residues on the RC surface near the cytochrome binding site will be mutated to residues having different molecular sizes and hydrophobicity. The pattern of changes in binding and electron transfer observed will be used to map out the binding interaction and possible pathways for electron transfer. %%% Biological systems derive much of their energy from electron transfer between proteins in biological membranes. Two major questions of electron transfer that are currently not understood are: How do electron donor and acceptor proteins recognize and bind to each other? and what is the pathway for electron transfer though proteins? The answers to both of these questions will be studied for the reaction between the bacterial reaction center and cytochrome c2, from the photosynthetic bacterium Rb. sphaeroides. ***

9304782冈村光合作用细菌通过光诱导的电子转移反应将光能转化为化学能，这种反应发生在被称为反应中心(RC)的色素蛋白复合体中。RC内的初始电荷分离通过来自移动电子载体细胞色素C2的电子转移而耦合到跨膜的电子转移。RC与细胞色素c2反应的重要特征是电子转移速率高，电子转移伙伴的分子识别能力强。这两种性质的结构基础将通过研究突变以下类型残基的影响来研究：(1)RC和细胞色素上的带电残基将被修饰以研究两个氧化还原伙伴之间的静电相互作用。Rc(负电荷残基到正电荷残基)和细胞色素(负电荷残基到正电荷残基)上的互补电荷变化将描绘出细胞色素RC络合物中特定的离子对相互作用。(2)细胞色素结合部位附近RC表面的不带电荷残基将被突变为具有不同分子尺寸和疏水性的残基。观察到的结合和电子转移的变化模式将被用来绘制结合相互作用和电子转移的可能路径。%生物系统的大部分能量来自生物膜中蛋白质之间的电子转移。电子传递的两个主要问题目前还不清楚：电子供体和受体蛋白是如何识别和结合的？通过蛋白质进行电子转移的途径是什么？这两个问题的答案将在细菌反应中心和来自光合细菌Rb的细胞色素c2之间的反应中进行研究。球形藻。***