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，并具有独特的策略来调节胁迫下的光合作用。由于目前对这些调节机制的了解有限，该项目利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，以解锁对物理原理的有价值的见解。对这些简单的光合作用机器的研究将为光合作用分子装置的进化和适应提供深入的见解。本项目将研究绿硫细菌（GSB）光合超复合体的整体蛋白质结构和组装动力学，重点研究光调控机制。该项目涉及对研究生和本科生的培训，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，这一努力与BioSense网络平台交织在一起，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是一种厌氧光自养生物，在光照强度低、营养匮乏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导光合能量。系统的一个组成部分是叶绿体，这是一个大型的、专门的、膜结合的光收集系统，它有效地捕获有限数量的光子，并将能量转移到反应中心。本项目旨在通过研究参与维持和调节光合能量转移的蛋白质的空间组织和组装动力学，揭示GSB如何调节光合系统有效地利用最小的光来满足细胞需求。尖端的冷冻电镜方法将用于研究组装动力学，而结构质谱（MS）将提供超复合物内高度灵活和非结构化的蛋白质结构域的信息。相关蛋白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。在不同的光强下，GSB光合系统的整体结构和组装动力学将被确定，以了解分子组装如何响应光强的变化，同时保持高水平的能量转移效率。从该项目中获得的知识将阐明GSB内的能量流，并有助于我们理解光合作用的分子进化。该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计划资助。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。

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.