Structural remodelling of photosynthetic membrane complexes

We aim at solving the structure of temporal photosynthetic supercomplexes such as Photosystem I (PSI) and photosystem II (PSII) during steady state and under stress conditions by the cryo EM technique. We will use thylakoid membranes isolated from green algae and higher plants as the source for the membrane complexes. The membranes will be treated by a combination of detergents, developed in our laboratory, and the various complexes will be isolated. We will utilize membranes isolated from temperature-sensitive mutant developed in our laboratory. At permissive temperature the isolated complexes are indistinguishable from the wild-type organism. In the none-permissive temperature the mutated complexes are depleted affecting the structure of the rest complexes. In the PSII temperature-sensitive mutant the organism utilizes exclusively PSI that are organized. This provides an unprecedented opportunity for structural determination of the relevant supercomplexes by the cryo EM technique.

本研究旨在借助冷冻电镜（cryo EM）技术，解析稳态及胁迫条件下光合超级复合物的结构，此类复合物包括光系统I（Photosystem I, PSI）与光系统II（Photosystem II, PSII）。本研究将以从绿藻及高等植物中分离得到的类囊体膜（thylakoid membranes）作为膜复合物的来源材料。我们将采用本实验室研发的复合去污剂处理上述膜组分，进而分离得到各类光合复合物。此外，本研究还将使用本实验室构建的温度敏感突变体（temperature-sensitive mutant）所分离得到的类囊体膜。在允许温度（permissive temperature）条件下，该突变体分离得到的复合物与野生型（wild-type）生物体的复合物无明显差异；而在非允许温度（non-permissive temperature）条件下，突变的复合物会发生耗竭，进而影响其余复合物的结构。在光系统II温度敏感突变体中，该生物体仅能形成组装完备的光系统I复合物。这为借助冷冻电镜技术解析相关光合超级复合物的结构提供了前所未有的契机。