Photo-assembly and Efficiency of Photosynthetic Water Oxidases: Probing the Catalytic Core Atom by Atom

光合水氧化酶的光组装和效率：逐个原子探测催化核心原子

• 批准号: 1213772
• 负责人: Gerard Dismukes
• 金额: $ 35万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1213772&HistoricalAwards=false
• 关键词: Photo; assembly; Efficiency; Photosynthetic; Water

In this award from the Chemistry of Life Processes Program in the Chemistry Division, Drs. G. Charles Dismukes and Gennady M. Ananyev, from Rutgers, The State University of New Jersey, seek to understand the physico-chemical principles that govern the assembly of the inorganic cofactors to form the water-oxidation complex (WOC) within Photosystem II (PSII) of photosynthetic organisms. This complex is nature's sole enzymatic solution for splitting water into molecular oxygen, protons, and electrons using sunlight. Despite apparent conservation of the WOC catalytic core, comprised of a Mn4CaO5 cluster, two chloride ions, and proximal amino acid residues, large differences in catalytic turnover rates occur between PSII species in vivo, indicative of functional differences that are not yet understood. The general experimental approach of this project uses organismal, biochemical and inorganic chemical strategies. The expected outcome will be to determine the allowed range of possible non-native inorganic cofactors that can support catalytic functioning of PSII-WOCs, determine their relative binding affinities and sites, and measure their kinetic performance in catalysis across different species. A long term goal is to understand the chemical basis for the evolutionary conservation of this enzyme class. These studies will be conducted using model photosynthetic organisms and using both native cells (in vivo) and isolated PSII complexes (in vitro). A number of complementary techniques will be used that allow comparison of kinetic performance over a wide range of flashing frequencies including: ultra-sensitive electrochemical O2 concentration and rate measurements, chlorophyll-detected Fast Repetition Rate fluorometry, and dye-detected kinetic pH measurements. Because no single inorganic component of the WOC works independently, we will conduct a systematic 'atom-by-atom' analysis that reveals their synergistic contributions.Advances in our understanding of the mechanism of photosynthetic water oxidation will inform alternative energy research in two areas. First, insights from the experiments proposed here may guide the design of genetically modified photosynthetic organisms that, for example, are expected to have improved biomass accumulation. Second, elucidation of the principles of photosynthetic water oxidation will guide the design of water oxidation catalysts for artificial photosynthesis systems capable of producing renewable fuels as alternative to fossil fuels. The proposed studies would allow research training of Rutgers undergraduate and postgraduate students, including women and those of underrepresented backgrounds, for future careers and advanced training in the renewable energy field. These proposed studies will leverage educational training programs sponsored by two NSF IGERT grants at Rutgers. The new instruments built and upgrades to existing instruments described in this proposal will improve the infrastructure available in our laboratory and accommodate other users at Rutgers, while supporting multiple collaborators and their funding agencies.

来自新泽西州立大学罗格斯大学的G.Charles Dismukes博士和Gennady M.Ananyev博士获得了来自化学系生命过程化学项目的这一奖项，他们试图了解支配无机辅助因子组装以在光合作用有机体的光系统II(PSII)内形成水氧化复合体(WOC)的物理化学原理。这种复合体是自然界唯一的酶溶液，可以利用阳光将水分解为分子氧、质子和电子。尽管WOC催化核心由一个Mn4CaO5簇、两个氯离子和邻近的氨基酸残基组成，但体内不同PSII物种之间的催化周转率存在很大差异，这表明功能差异尚不清楚。这个项目的一般实验方法使用了有机、生化和无机化学策略。预期的结果将是确定支持PSII-WOCs催化功能的可能的非天然无机辅因子的允许范围，确定它们的相对结合亲和力和位置，并测量它们在不同物种中的催化动力学性能。一个长期的目标是了解这种酶类进化保守的化学基础。这些研究将使用模型光合作用有机体和使用天然细胞(体内)和分离的PSII复合体(体外)进行。将使用一些补充技术来比较各种闪光频率下的动力学性能，包括：超灵敏的电化学O2浓度和速率测量、叶绿素检测的快速重复频率荧光法和染料检测的动态pH测量。由于WOC中没有单一的无机成分独立发挥作用，我们将进行系统的逐个原子的分析，揭示它们之间的协同作用。我们对光合作用水氧化机理的理解的进展将为两个领域的替代能源研究提供信息。首先，这里提出的实验的见解可能会指导转基因光合作用生物的设计，例如，预计会改善生物量积累。其次，阐明光合作用水氧化的原理将指导用于人工光合作用系统的水氧化催化剂的设计，该系统能够生产可再生燃料作为化石燃料的替代品。拟议的研究将使罗格斯大学的本科生和研究生，包括妇女和代表人数不足的学生，能够为未来的职业生涯和可再生能源领域的高级培训提供研究性培训。这些拟议的研究将利用由罗格斯大学的两笔NSF IGERT赠款赞助的教育培训计划。本提案中描述的新仪器和对现有仪器的升级将改善我们实验室现有的基础设施，并容纳罗格斯大学的其他用户，同时支持多个合作者及其资助机构。