NSF/MCB-BSF High-resolution mapping of the protein landscape in plant photosynthetic membranes

地球上的生命以光合作用为燃料，光合作用将阳光转化为代谢能量形式。在植物中，光合能量转换是通过叶绿体内高度专门化的类囊体膜中的色素蛋白复合物实现的。类囊体膜中的蛋白质景观对不可预测的环境变化（即云引起的阳光强度波动，风中叶片的自遮蔽）的动态响应触发了植物生存所必需的光保护高能猝灭（qE）。该项目将绘制QE诱导的蛋白质景观动态类囊体膜的分子分辨率作为理解关键光合功能的基础。拟议工作的智力价值是，它定义了一个创新和完整的方法管道，从最先进的电子显微镜到粗粒计算机模拟，这将提供对光合光捕获和电子传输的定量理解。这条管道将导致迫切需要的动态结构功能的类囊体膜的关系的见解。此外，它正在以前所未有的分辨率将蛋白质景观分析提高到一个新的水平，以增加我们对光合能量转换的深入了解。该项目的更广泛的影响是双重的：首先，它将为来自代表性不足群体的本科生提供实践研究经验，并为计算化学课程建立一个新的基于计算机的教学工具。第二，所提出的工作的社会效益预期为作物植物和生物燃料前景的改善，因为事实证明，通过生物工程优化和调整的QE机制可能是一个强大的工具，以提高植物性能。为了生成类囊体蛋白景观的高分辨率蛋白质图谱作为基础，以提供对QE依赖的光捕获和电子传递调节的机制理解，将追求三个具体目标。目标#1：建立不同qE状态的高分辨率蛋白质图谱。植物将使用电子显微镜和成分分析，这将导致详细的粗粒类囊体蛋白景观检查。目的#2：确定QE诱导的蛋白质景观变化如何影响光捕获和光保护QE。类囊体膜的粗粒蛋白质图谱将被用来模拟光合光捕获，以解释测量数据。目标#3：确定蛋白质景观中QE触发的开关如何控制扩散依赖的电子传递。一个动态的蛋白质景观模型的整个类囊体膜将被开发，允许模拟整个光合电子传递，以了解在体内的数据。这个美国/以色列合作项目得到了美国国家科学基金会和以色列两国科学基金会的支持。这个奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Life on earth is fueled by photosynthesis, which converts sunlight into metabolic energy forms. In plants, photosynthetic energy conversion is realized by pigment-protein complexes that are harbored in highly specialized thylakoid membranes inside the chloroplasts. The dynamic response of the protein landscape in thylakoid membranes to unpredictable environmental changes (i.e. fluctuations in sunlight intensity by clouds, self-shading of leaves in wind) triggers photoprotective high-energy quenching (qE) that is essential for the survival of the plant. The project will map qE-induced protein landscape dynamics in thylakoid membranes with molecular resolution as a basis for understanding key photosynthetic functions. The intellectual merit of the proposed work is that it defines an innovative and complete pipeline of methods, ranging from state-of the art electron microscopy to coarse grain computer simulations, which will provide a quantitative understanding of photosynthetic light harvesting and electron transport. This pipeline will lead to urgently needed insights into dynamic structure-function relationships in thylakoid membranes. Furthermore, it is raising protein landscape analysis to a new level with unprecedented resolution to increase our in-depth understanding of photosynthetic energy conversion. The broader impact of the project is twofold: First, it will provide hands-on research experience to undergraduate students from underrepresented groups, and establish a new computer-based teaching tool for a computational chemistry course. Second, social benefits of the proposed work are expected for the improvement of crop plants and biofuel prospects since it turns out that optimization and adjustment of the qE mechanisms by bioengineering could be a powerful tool to increase plant performances. To generate high-resolution protein maps of the thylakoid protein landscape as basis to provide mechanistic understanding for the qE-dependent regulation of light-harvesting and electron transport, three specific aims will be pursued. Aim #1: Establishing high-resolution protein maps for different qE states. Plants will be examined using electron microscopy and compositional analysis which will lead to detailed coarse grain thylakoid protein landscapes. Aim #2: Determine how qE-induced changes in protein landscapes impact light harvesting and photoprotective qE. Coarse grain protein maps of thylakoid membranes will be used to model photosynthetic light harvesting in order to interpret measured data. Aim #3: Determine how qE-triggered switches in protein landscapes control diffusion dependent electron transport. A dynamic protein landscape model for the entire thylakoid membrane will be developed that allows simulation of the whole photosynthetic electron transport to understand in vivo data. This collaborative US/Israel project is supported by the US National Science Foundation and the Israeli Binational Science Foundation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.