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NSF/MCB-BSF:Understanding Photosynthetic Energy Conversion on the Mesoscale

NSF/MCB-BSF：了解中尺度的光合能量转换

基本信息

批准号：
1616982
负责人：
Helmut Kirchhoff
金额：
$ 70.84万
依托单位：
Washington State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-08-15 至 2020-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1616982&HistoricalAwards=false
关键词：
NSF MCB BSF Understanding Photosynthetic

项目摘要

The photosynthetic conversion of sunlight requires structural coordination between nanometer-sized protein complexes embedded within the thylakoid membrane of chloroplasts. The exact structural positioning of the energy transforming protein complexes in the membrane on the 100 nanometer length scale (called the mesoscopic level) is a key element for the functionality and regulation of biological energy conversion. Missing information about mesoscopic characteristics and their dynamic response to environmental cues represents a significant gap in the knowledge base. In particular, it is not understood what factors determine mesoscopic features in thylakoid membranes and what physicochemical forces are involved. The proposed work aims to fill this critical gap. Knowing how plants optimize and regulate photosynthetic energy conversion on the mesoscopic length scale will not only have a direct impact on basic photosynthesis research but also has a strong eco-physiological component by understanding how changes in plant habitats control photosynthetic performance via modifications in mesoscopic membrane features. The computer model that will be developed in the proposed work has the potential to unravel the underlying design principles of the photosynthetic machinery that can be used for the identification of new approaches to design crop plants. The importance of mesoscopic characteristics and dynamics of thylakoid membranes in improving crop plants has been neglected thus far. Furthermore, the proposed work has a strong focus on high-quality education of students and postdocs. Based upon previous successful experiences with NSF-supported undergraduates, six undergraduates from underrepresented groups will be recruited and offered supported research training opportunities. The objective of this research is to unravel the role of the lipid composition and reversible protein phosphorylation for mesoscopic protein organization and its dynamics in stacked grana thylakoid membranes (covers about 60% of the whole thylakoid membrane). The central hypothesis is that physicochemical properties of the lipid matrix and the phosphorylation of grana hosted proteins are key determinants for the supramolecular protein arrangement in grana. The PI and his collaborators will determine the impact of the lipid matrix for the supramolecular protein organization in grana. The photosystem II (PSII) arrangement in grana membranes will be mapped and mathematically analyzed for wildtype (WT) and lipid and fatty acid mutants by cryo-scanning electron microscopy (SEM) on freeze-fractured membranes. Next, the mesoscopic dynamics induced by reversible protein phosphorylation will be determined by comparing PSII maps of WT protein with those of mutants with protein hyper- or hypo-phosphorylation. Finally, the forces that control protein ensemble behavior will be determined by applying coarse grain computer modeling. The project will provide unprecedented insight into structure-function relationship of photosynthetic membranes on the mesocopic level and in addition to in-depth structural characterizations of changes in the mesoscopic protein organization and PSII supercomplex stability by alterations of the lipid/fatty acid composition or protein phosphorylation pattern. This contribution is significant because it identifies central mechanisms that control and regulate supramolecular protein dynamics in stacked thylakoid membranes required for efficient photosynthetic energy conversion in ever-changing environments.This collaborative US/Israel project is supported by the US National Science Foundation and the US-Israel Binational Science Foundation.

阳光的光合作用转换需要嵌入叶绿体类囊体膜的纳米蛋白质复合体之间的结构协调。膜中能量转换蛋白复合体在100纳米尺度(称为介观水平)上的准确结构定位是生物能量转换功能和调控的关键因素。缺少关于介观特征及其对环境线索的动态反应的信息，代表着知识库中的一个重大缺口。特别是，目前还不清楚是什么因素决定了类囊体膜的介观特征，以及什么物理化学力参与了这一过程。拟议的工作旨在填补这一关键空白。了解植物如何在中观尺度上优化和调节光合作用能量转换，不仅对光合作用的基础研究有直接影响，而且通过了解植物生境的变化如何通过改变中观膜特性来控制光合作用，也具有很强的生态生理作用。在拟议的工作中开发的计算机模型有可能解开光合作用机器的基本设计原则，这些原则可用于识别设计作物的新方法。到目前为止，类囊体膜的介观特性和动力学在改良作物方面的重要性一直被忽视。此外，拟议的工作非常注重对学生和博士后的高质量教育。根据以往NSF资助的本科生的成功经验，将从代表性不足的群体中招募6名本科生，并提供支持性研究培训机会。本研究的目的是揭示脂质组成和可逆蛋白磷酸化在堆叠的基粒类囊体膜(约占整个类囊体膜的60%)中介观蛋白组织及其动力学中的作用。中心假设是脂质基质的物理化学性质和基粒宿主蛋白的磷酸化是基粒中超分子蛋白质排列的关键决定因素。PI和他的合作者将确定脂质基质对基粒中超分子蛋白质组织的影响。冷冻破裂膜上的光系统II(PSII)排列将通过冷冻扫描电子显微镜(SEM)对野生型(WT)、脂类和脂肪酸突变体进行定位和数学分析。下一步，通过比较WT蛋白的PSII图谱和具有蛋白质高或低磷酸化的突变体的PSII图谱，将确定可逆蛋白质磷酸化诱导的介观动力学。最后，将通过应用粗粒计算机建模来确定控制蛋白质整体行为的力。该项目将在中观水平上对光合膜的结构-功能关系提供前所未有的洞察，并深入了解由于脂类/脂肪酸组成或蛋白质磷酸化模式的变化而导致的中观蛋白质组织和PSII超复合体稳定性的变化的结构特征。这一贡献意义重大，因为它确定了控制和调节堆叠类囊体膜中超分子蛋白质动力学的核心机制，这是在不断变化的环境中进行高效光合作用能量转换所必需的。这一美国/以色列合作项目得到了美国国家科学基金会和美国-以色列双国科学基金会的支持。