CAREER: Structural Discovery of Super-Complexes Regulating Energy Flow in Photosynthesis

产氧光合作用通过产生氧气并为碳固定提供能量来维持地球上的生命。不断增加的人口不断挑战粮食和能源供应，因此需要不断创新，以多种方式提高光合作用的生产率。这项研究项目将发现植物如何在两条不同的能量途径之间引导叶片吸收的光能。这两种途径的结果被称为线性和循环电子流，在植物细胞内产生不同的能量载体。这些能量载体在不同的条件下被不同地利用，它们之间的平衡对植物的生长和适应至关重要。该项目旨在发现使用结构生物学和蛋白质工程方法指导这一决定的新组件和机制。该项目的另一个目标是获得植物中这些路由机制的分子水平图像，这些植物利用一种特殊形式的光合作用，称为C4光合作用。C4光合作用被地球上一些最重要的作物物种利用，如玉米、甘蔗和高粱，并赋予这些植物许多使它们成为如此成功的作物的优势，例如，改善水分利用和更高的光合作用效率。该项目将使用高粱作为平台，发现控制电子流动的组件和机制，并可能导致高粱的一些独特特性。高粱比玉米更适应温暖和干燥的条件。为了提高对项目科学成果和一般结构生物学的可及性，将根据项目结果开发科学准确的虚拟现实场景。这些将在基础生物化学课程中使用，并公开提供。将为退伍军人提供暑期研究实习机会，让他们积极参与这一研究项目，使他们能够探索研究作为职业道路。我们控制和操纵光合作用的能力受到严重限制。该项目的长期目标是发展对光合超复合体功能的高水平理解，以及在光合作用有机体中操纵其特性的能力。为了实现这一目标，该项目将在真核生物中发现光系统I(PSI)复合体的新结构。PSI是自然界中最复杂的组装之一。像许多大型细胞结构一样，PSI与细胞因子相互作用以承载不同的功能，这一事实在我们对PSI的结构描述中仍然没有体现出来。光合作用中的电子流动主要遵循两种模式，线性电子流动或循环电子流动(分别为LEF或CEF)。通过平衡这两条途径，光合作用有机体使光合作用机器的输出适应细胞的需要。改造光合作用有机体以实现更高的生产率和合成特定化学品的潜力是巨大的，但需要改变这台机器的基本能量需求。这项建议使用低温EM并辅之以功能分析来解决这个问题，以发现调节PSI周围能量流动的超络合物。通过确定这些络合物的高分辨率结构，我们对光合作用中控制电子流模式的基本系统的机械理解将大大提高。该项目由分子和细胞生物科学部的分子生物物理组资助。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Oxygenic photosynthesis sustain life on earth by producing oxygen and providing energy for carbon fixation. Increased human population constantly challenges food and energy supplies thus requiring continued innovation to increase the productivity of photosynthesis in multiple ways. This research project will discover how plants direct light energy absorbed in leaves between two different energetic routes. The outcomes of these two routes, which are called linear and cyclic electron flow, produces different energy carries within plant cells. These energy carries are utilized differentially under different conditions and the balance between them is paramount for plant growth and adaptation. The project aims to discover new components and mechanisms that direct this decision using structural biology and protein engineering approaches. An additional goal of the project is to obtain molecular level images of these routing mechanisms in plants that utilize a special form of photosynthesis called C4 photosynthesis. C4 photosynthesis is employed by some of the most important crop species on the planet, Corn, Sugarcane and Sorghum, and confers to these plants many of the advantages that make them such successful crops, for example, improved water usage and higher photosynthetic efficiency. The project will use Sorghum, a plant better adapted to warm and dry conditions then Corn, as a platform to discover components and mechanisms that control electron flow and may be responsible for some of Sorghum’s unique properties. To improve accessibility to the project’s scientific results and to structural biology in general, scientifically accurate virtual reality scenes will be developed based on the project results. These will be used in basic biochemistry courses and made publicly available. A summer research internship will be offered to veterans to actively participate in this research project to enable exploration of research as career path. Our ability to control and manipulate photosynthesis is severely limited. The long-term goal of the project is to develop a high-level understanding of the function of photosynthetic supercomplexes together with the ability to manipulate their properties in photosynthetic organisms. To achieve this, the project will discover new structures of the photosystem I (PSI) complex in eukaryotes. PSI is one of the most complicated assemblies in nature. Like many large cellular structures, PSI interacts with cellular factors to carry distinct functions, a fact which is still not manifested in our structural description of PSI. Electron flow in photosynthesis follows two main modes, linear or cyclic electron flow (LEF or CEF respectively). By balancing these two pathways, photosynthetic organisms adapt the output of the photosynthetic machinery to cellular needs. The potential for engineering photosynthetic organisms to achieve higher productivity and to synthesize specific chemicals is great but requires changing the basic energy requirements from this machinery. This proposal tackles this issue using cryo-EM supplemented with functional analysis to discover supercomplexes adjusting energy flow around PSI. By determining high-resolution structures of these complexes our mechanistic understanding of the basic systems controlling electron flow modes in photosynthesis will greatly improve. This project is funded by the Molecular Biophysics Cluster in the Division of Molecular and Cellular Biosciences.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.