Structural and Functional Analysis of Photosystem I

蓝藻光系统I反应中心是一个光驱动的 氧化还原酶催化电子从细胞色素c533传递到 铁氧还蛋白。 这项研究计划的长期目标是 了解光系统I反应的结构和功能 中心 在这个项目中，生化分解和重组 结合定点突变和蛋白质 在大肠杆菌中过量生产，以产生具有改变的 光谱和电子传输性质。 建立在我们的 最新的结果和开发的工具和构建的突变体 在当前资助期内，将实现以下长期目标 应处理： 1. FA和/或FB在室温光还原反应中的作用 铁氧还蛋白（或黄素氧还蛋白）和NADP+通过FNR。 2. 鉴定的两种形式FNR的生化表征 在聚球藻7002中。 3. 编码PS I的剩余基因的表征 聚球藻属PCC 7002中的多肽。 4. PsaD和PsaE在PS I结构和功能中的作用 5. PS I与植物细胞间特异性相互作用的机制 复合物和铁氧化还原蛋白和黄素氧还蛋白。 6. PsaC、PsaD、PsaE和FNR的三维结构 proteins. 7. 电子的PsaE和NdHF依赖路径的性质 在P700+再还原中运输。 %%% 地球上的所有生命最终都依赖于太阳光能的捕获 在光合作用过程中，一个过程，导致减少， 二氧化碳的固定和氧气的释放作为一种副作用， 产品 光能捕获和转换发生在 称为反应中心的多蛋白质复合物，其利用 引发氧化还原反应的光能和电子 导致化学能产生的转移事件 (in ATP形式）和化学还原剂（NADPH形式）。 在绿色植物中的产氧光合作用中， 藻类和被称为蓝细菌的细菌--这两种细菌的合作 需要反应中心，表示为光系统I和II。 的 本文提出的研究的长期目标是了解 光系统I反应中心的结构组织， 解开电子转移事件的具体细节 电荷分离、电荷稳定和电子转移 在这个反应中心的可溶性载体。 拟建项目 是两个不同研究学科的结合， 我们的研究密切合作和协调的结果 与约翰·H博士的实验室的活动。戈德贝克 （部门）of Biochemistry，University of Nebraska）。 的组合 现代分子遗传学，重组DNA技术，位点 定向诱变、蛋白质过量生产和蛋白质 生物化学（我的实验室）与生物化学重组相结合， 现代超快激光光谱学，电子自旋共振（ESR） 光谱和其他生物物理测量（Golbeck 实验室）。 我们还将共同描述替代方案 涉及光系统I反应的电子传递途径 中心（例如，循环电子传递）和功能的 交替电子受体铁氧还蛋白和黄素氧还蛋白。 通过 我们的工作，我们希望提供一个更好的了解 光合太阳能捕获和光化学转换。

The cyanobacterial Photosystem I reaction center is a light-driven oxidoreductase catalyzing electron transport from cytochrome c533 to ferredoxin. The long-term goal of this research program is to understand the structure and function of the Photosystem I reaction center. In this project biochemical resolution and reconstitution are combined with site-directed mutagenesis and protein overproduction in E.coli to produce reaction centers with altered spectroscopic and electron transport properties. Building upon our most recent results and the tools developed and mutants constructed in the current funding period, the following long-term goals will be addressed: 1. The roles of FA AND/OR FB in the room-temperature photoreduction of ferredoxin (or flavodoxin) and NADP+ via FNR. 2. Biochemical characterization of the two forms of FNR identified in Synechococcus sp. PCC 7002. 3. Characterization of the remaining genes encoding PS I polypeptides in Synechococcus sp. PCC 7002. 4. The roles of PsaD and PsaE in PS I structure and function. 5. The mechanism of the specific interactions between the PS I complex and ferredoxins and flavodoxin. 6. The 3-dimensional structures of the PsaC, PsaD, PsaE, and FNR proteins. 7. The nature of the PsaE- and NdhF-dependent paths of electron transport in P700+ re-reduction. %%% All life on Earth ultimately depends on solar light energy capture during photosynthesis, a process which leads to the reduction and fixation of carbon dioxide and the evolution of oxygen gas as a by- product. Light energy capture and transduction takes place in multiprotein complexes known as reaction centers, which utilize the light energy to initiate oxidation-reduction reactions and electron transfer events which result in the production of chemical energy (in the form of ATP) and chemical reductant (in the form of NADPH). In oxygenic photosynthesis--the type which occurs in green plants, algae, and bacteria known as cyanobacteria--the cooperation of two reaction centers, denoted Photosystems I and II, are required. The long-term goal of the research here proposed is to understand the structural organization of the Photosystem I reaction center and to unravel specific details of the electron transfer events that lead to charge separation, charge stabilization, and electron transfer to soluable carriers in this reaction center. The proposed project is a marriage of two different research disciplines and is the result of a close collaboration and coordination of our research activities with those of the laboratory of Dr. John H. Goldbeck (Dept. of Biochemistry, University of Nebraska). A combination of modern molecular genetics, recombinant DNA technology, site directed mutagenesis, protein overproduction and protein biochemistry (my lab) is combined with biochemical reconstitution, modern ultra-fast laser spectroscopy, electron spin resonance (ESR) spectroscopy, and other biophysical measurements (the Golbeck laboratory). We will also jointly characterize alternative electron transport pathways involving the Photosystem I reaction center (e.g, cyclic electron transport) and function of the alternative electron acceptors ferredoxin and flavodoxin. Through our work we hope to provide a better understanding of photosynthetic solar energy capture and photochemical conversion.