Chen Ming, He Yujie, Liu Dongyang, Tian Lijin, Xu Pengqi, Liu Xuan, Pan Yihang, Dong Shuqi, He Jun, Zhang Ying
The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China.
Center for Cell Fate and Lineage (CCLA), Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China.
Front Microbiol. 2022 May 6;13:876122. doi: 10.3389/fmicb.2022.876122. eCollection 2022.
The diversity of photosystem oligomers is essential to understanding how photosynthetic organisms adapt to light conditions. Due to its structural and physiological significance, the assembly of the PSI supercomplex has been of great interest recently in terms of both chloroplast and cyanobacteria. In this study, two novel photosystem I supercomplexes were isolated for the first time from the low light incubated culture of filamentous cyanobacterium sp. PCC 7120. These complexes were defined as PSI hexamers and octamers through biochemical and biophysical characterization. Their 77K emission spectra indicated that the red forms of chlorophylls seemed not to be affected during oligomerization. By cryo-EM single-particle analysis, a near-atomic (7.0 Å) resolution structure of a PSI octamer was resolved, and the molecular assemblies of a stable PSI octamer were revealed.
光系统寡聚体的多样性对于理解光合生物如何适应光照条件至关重要。由于其结构和生理意义，最近从叶绿体和蓝细菌两方面来看，PSI超复合体的组装都备受关注。在本研究中，首次从丝状蓝细菌PCC 7120的低光照培养物中分离出两种新型光系统I超复合体。通过生化和生物物理表征，这些复合体被定义为PSI六聚体和八聚体。它们的77K发射光谱表明，叶绿素的红色形式在寡聚化过程中似乎未受影响。通过冷冻电镜单颗粒分析，解析了PSI八聚体的近原子（7.0 Å）分辨率结构，并揭示了稳定PSI八聚体的分子组装。
