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。在植物中，光合作用能量的转换是由叶绿体内高度特化的类囊体膜中的色素-蛋白质复合物实现的。类囊体膜中的蛋白质景观对不可预测的环境变化（如云对阳光强度的波动，风对叶子的自遮阳）的动态响应触发了光保护性高能猝灭（qE），这对植物的生存至关重要。该项目将以分子分辨率绘制类囊体膜中酶诱导的蛋白质景观动态，作为理解关键光合功能的基础。这项工作的智力价值在于，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粮计算机模拟，这将提供对光合作用光收集和电子传递的定量理解。这条管道将导致迫切需要深入了解类囊体膜的动态结构-功能关系。此外，它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。该项目的广泛影响是双重的：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种新的基于计算机的教学工具。其次，本研究的社会效益有望改善作物和生物燃料的前景，因为生物工程对qE机制的优化和调整可能是提高植物性能的有力工具。为了生成类囊体蛋白景观的高分辨率蛋白质图，作为基础，为光收集和电子传输的qe依赖性调节提供机制理解，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进行检查，这将导致详细的粗粒类囊体蛋白质景观。目标2：确定qE诱导的蛋白质景观变化如何影响光收集和光保护性qE。类囊体膜的粗粒蛋白图将用于模拟光合作用光收获，以便解释测量数据。目标#3：确定蛋白质景观中由qe触发的开关如何控制依赖扩散的电子传递。整个类囊体膜的动态蛋白质景观模型将被开发，允许模拟整个光合电子传递，以了解体内数据。这个美国/以色列合作项目由美国国家科学基金会和以色列两国科学基金会支持。该奖项反映了美国国家科学基金会的法定使命，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.