Mechanism and Macromolecular Organization in Photosynthetic Reaction Centers

光合反应中心的机理和大分子组织

• 批准号: 0918782
• 负责人: Steven Boxer
• 金额: $ 124.76万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0918782&HistoricalAwards=false
• 关键词: Mechanism; Macromolecular; Organization; Photosynthetic; Reaction

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The objective of this research is to understand the mechanisms of charge separation and recombination in photosynthetic reaction centers (RCs) and the higher-order organization of photosynthetic membranes. This research project focuses on three areas: (i) the mechanism of electron transfer in RCs where the primary electron acceptor has been removed; (ii) the use of vibrational spectator probes to quantify electrostatics in the RC; and (iii) the development of advanced imaging techniques using well-defined photosynthetic complexes and assemblies as a model system. By working with RCs in which normal electron transfer is blocked, new pathways can be revealed in a clean background and important intermediates can be trapped. In particular, the kinetics and energetics of electron transfer along the ordinarily non-functional side of the RC can be studied in depth. This project will investigate the orientation of a particular amino acid that is believed to modulate reaction energetics. A suite of methods will introduce spectator vibrational probes into the RC to measure differences in electrostatic fields in symmetry-related positions, as well as probe changes in fields as electron transfer occurs. Areas (i) and (ii) focus on specific, well-defined questions that arise in bacterial photosynthesis; the results and methods will apply to more complex photosynthetic organisms and the broad area of biological electron transfer. Area (iii) uses photosynthetic systems, but will impact the development of new approaches for characterizing membranes and membrane proteins in general. Imaging mass spectrometry will be pushed to its limit using the highly organized photosynthetic membrane, in particular to see whether integral membrane protein organization can be visualized. A "membrane interferometer" has been developed that combines advanced fabrication, membrane assembly and optics in a device that is highly sensitive to membrane curvature and osmotic pressure. Photosynthetic proteins will be used to test the precision of this interferometer, to test hypotheses concerning the impact of photosynthetic membrane proteins on membrane curvature and budding, and as reporters of membrane curvature upon incorporation of channels that are sensitive to membrane tension.Sustained support in this area has led to the development of many new approaches for studying electron transfer reactions, one of the most important classes of reactions in physical and biological systems. Nearly every spectroscopic, structural, and theoretical method has been applied to some aspect of RC and photosynthetic membrane function. In many cases this was the first example of new physical approaches applied to a biological problem, often leading to significant improvements in the physical and theoretical methods, and these concepts and methods are now used in many other fields. Assembly of RCs on surfaces opened an entirely new area of technology, membrane patterning, which is now used in many laboratories and is the basis of efforts to use membrane and membrane-protein arrays for screening in several biotechnology companies. This general area of research has been a tremendous source of training for undergraduates, graduate students and postdoctoral fellows, often serving as a bridge between the physical sciences and biology. The PI has given more than 100 invited talks at universities, national labs, companies and scientific conferences worldwide over the past 5 years. Viewed in broadest terms, concepts and results from photosynthesis research have impacted solar energy research and the emerging area of molecular electronics.

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。本研究的目的是了解光合作用反应中心(RCS)中的电荷分离和复合机制以及光合膜的高阶组织。这项研究项目集中在三个领域：(I)RCS中主要电子受体被移除的电子转移机制；(Ii)使用振动旁观者探针来量化RC中的静电；以及(Iii)使用定义明确的光合作用复合体和组件作为模型系统来开发先进的成像技术。通过与阻止正常电子转移的RCS合作，可以在干净的背景下揭示新的路径，并可以捕获重要的中间体。特别是，可以深入研究沿着RC通常非官能化一侧的电子转移的动力学和能量学。这个项目将研究一种特定氨基酸的取向，这种氨基酸被认为是调节反应能量的。一套方法将把旁观者振动探头引入RC，以测量与对称相关位置的静电场的差异，以及在发生电子转移时探测场的变化。领域(I)和(Ii)侧重于细菌光合作用中出现的具体、明确的问题；结果和方法将适用于更复杂的光合作用有机体和广泛的生物电子转移领域。面积(III)使用光合作用系统，但将影响膜和膜蛋白总体特性的新方法的发展。成像质谱学将利用高度组织化的光合膜将其推向极限，特别是看看是否可以可视化完整的膜蛋白结构。一种“膜干涉仪”已经被开发出来，它结合了先进的制造、膜组装和光学技术，这种装置对膜曲率和渗透压高度敏感。光合作用蛋白质将被用来检验这种干涉仪的精确度，检验有关光合膜蛋白质对膜曲率和发芽的影响的假说，以及作为膜曲率的报告者加入对膜张力敏感的通道。在这一领域的持续支持导致了许多研究电子转移反应的新方法的发展，电子转移反应是物理和生物系统中最重要的反应之一。几乎每一种光谱、结构和理论方法都被应用于Rc和光合膜功能的某些方面。在许多情况下，这是将新的物理方法应用于生物学问题的第一个例子，通常导致物理和理论方法的重大改进，这些概念和方法现在被用于许多其他领域。在表面组装RCS开辟了一个全新的技术领域--膜图案化，这一技术现在被许多实验室使用，并为几家生物技术公司使用膜和膜蛋白质阵列进行筛选奠定了基础。这一一般研究领域一直是本科生、研究生和博士后研究员的巨大培训来源，通常是物理科学和生物学之间的桥梁。在过去的5年里，PI在世界各地的大学、国家实验室、公司和科学会议上进行了100多次应邀演讲。从最广泛的角度来看，光合作用研究的概念和结果已经影响到太阳能研究和新兴的分子电子学领域。