Investigating assembly dynamics of a bacterial photosynthetic system and its impact on light-harvesting efficiency

光合细菌在不同的环境中茁壮成长，并拥有独特的策略来调节光合作用。由于目前对这些调控机制的了解有限，该项目使用一系列生物物理技术深入研究这些细菌的光合作用过程，以揭示对物理原理的宝贵见解。对这些简单的光合机器的研究将为光合分子装置的进化和适应提供深入的了解。本计画将探讨绿色硫细菌光合作用超复合体的整体蛋白质结构与组装动力学，并著重于光调控机制。该项目涉及培训研究生和本科生，特别是那些来自代表性不足的少数民族背景的学生，使他们具备必要的技能，为这一前沿研究做出贡献。此外，这一奋进与BioSense Network平台交织在一起，该平台将吸引高中教师和学生，激发他们对科学，技术，工程和数学领域的兴趣。GSB是厌氧光合自养生物，在低光照强度和缺乏营养的极端条件下茁壮成长。他们已经开发出一种高效的系统来收集和转换光合能量。一个系统组件是叶绿体，一个大的，专门的，膜结合的光捕获系统，有效地捕获有限数量的光子，并将能量转移到反应中心。该项目旨在揭示GSB如何调节这种光合系统，通过研究蛋白质的空间组织和组装动力学，有效地利用最小的光来满足细胞需求，参与维持和调节光合能量转移。尖端的cryo-EM方法将用于研究组装动力学，而结构质谱（MS）将提供有关超复合物内高度灵活和非结构化蛋白质结构域的信息。相关蛋白质复合物的空间排列将通过低温电子断层扫描可视化，以确定它们在细胞环境中的位置。GSB光合系统的整体结构和组装动力学将在各种光强度下确定，以了解分子组装如何响应光水平的变化，同时保持高水平的能量传递效率。从这个项目中获得的知识将阐明GSB中的能量流，并有助于我们理解光合作用中的分子进化。这个项目由生物科学理事会分子和细胞生物科学部的分子生物物理学项目资助。这个奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响进行评估，被认为值得支持审查标准。

Photosynthetic bacteria thrive in diverse environments and possess unique strategies to regulate photosynthesis under stress. As current knowledge of these regulatory mechanisms is limited, this project delves into the photosynthetic processes of these bacteria using a range of biophysical techniques to unlock valuable insights into the physical principles. The study of these simpler photosynthetic machines will provide insight into the evolution and adaptation of the photosynthetic molecular apparatus. This project will investigate the overall protein architecture and assembly dynamics of the green sulfur bacterial (GSB) photosynthetic supercomplex, focusing on light regulatory mechanisms. This project involves the training of graduate and undergraduate students, particularly those from underrepresented minority backgrounds, equipping them with the necessary skills to contribute to this cutting-edge research. In addition, this endeavor is intertwined with the BioSense Network platform, which will engage high-school teachers and students, to ignite their interest in the fields of science, technology, engineering, and mathematics. GSB are anaerobic photoautotrophs thriving in extreme conditions with low light intensity and scarce nutrients. They have developed a highly efficient system for harvesting and transducing photosynthetic energy. One system component is the chlorosome, a large, specialized, membrane-bound light harvesting system, that efficiently captures the limited number of photons available and transfers the energy to the reaction center. This project aims to uncover how GSB regulates this photosynthetic system to efficiently use minimal light for cellular needs, by studying the spatial organization and assembly dynamics of proteins, involved in maintaining and regulating photosynthetic energy transfer. Cutting-edge cryo-EM methods will be applied to study the assembly dynamics, while structural mass spectrometry (MS) will provide information about highly flexible and unstructured protein domains within the supercomplex. The spatial arrangement of relevant protein complexes will be visualized with Cryogenic electron tomography to determine their positions in the cellular context. The overall architecture and assembly dynamics of the GSB photosynthetic system will be determined under various light intensities to understand how the molecular assembly responds to changes in light levels while maintaining high levels of energy transfer efficiency. The knowledge gained from this project will shed light on energy flow within GSB and contribute to our understanding of molecular evolution in photosynthesis.This project is funded by the Molecular Biophysics program of the Molecular and Cellular Biosciences Division in the Biological Sciences Directorate.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.