Oxygen release photosynthesis is the process of large-scale utilization of solar energy to synthesize carbon dioxide and water into organic compounds and release oxygen, which is almost the basis for the survival and development of all life. The primary reaction of converting light energy into chemical energy in oxygen releasing photosynthesis is usually completed by the light system located on the thylakoid membranes of photosynthetic organisms such as plants, algae, and cyanobacteria, driven by visible light. Acaryochloris marina (A. marina) is a unique blue-green algae that uses chlorophyll d (Chl d) as the main photosynthetic pigment. It can absorb low-energy far red light through Chl d to drive oxygen releasing photosynthesis. However, A The molecular mechanism by which Marina Photosystem II (PSII) utilizes far-red light is still unclear.
The Research Group of Structural Biology of Photosynthetic Membrane Protein, Institute of Botany, Chinese Academy of Sciences, in conjunction with Southern University of Science and Technology and Zhejiang University, first analyzed A The structure of Marina Optical System II - Capture Antenna (PSII Pcb) tetramer super complex. This super complex is approximately 340 Å, 200 Å, and 90 Å in length, width, and height, respectively. It consists of two PSII core dimers and 16 symmetrical Pcb antenna subunits on both sides, containing 80 protein subunits and 624 cofactors, with a total molecular weight of approximately 1.9 Mda. Each PSII monomer contains 15 core subunits, 1 unknown protein subunit, and 4 Pcb antenna subunits. This structure reveals for the first time A The characteristics of peripheral ligands in the electron transfer chain of Marina photosystem II reaction center, the structural characteristics of four types of Pcb antenna subunits, and the assembly principle of super large complexes. Based on the structural characteristics of the complex and the arrangement of pigment molecules, researchers have discovered multiple pathways for capturing and transmitting light energy in this complex.
This achievement breaks the previous understanding of the existence form and light energy utilization mechanism of the photosystem II complex, laying a structural foundation for revealing the mechanism of Chl d type blue-green algae utilizing far red light molecules, and providing information for exploring the diversity of light energy utilization and light adaptation mechanisms in photosynthetic organisms. It is expected to provide inspiration for designing new broadband light energy utilization photosynthetic systems and high light efficiency crops.
Recently, the relevant research results were published in Science Advances. The research work was supported by the National Key R&D Program, the National Natural Science Foundation of China, the Chinese Academy of Sciences Youth Team Program for Stable Support in Basic Research, the China Postdoctoral Science Foundation, the "Outstanding Postdoctoral Principal" of Southern University of Science and Technology, and the Public Technical Service Center of the Institute of Botany, the Freeze Electron Microscope Center of the Public Service Platform for Scientific Research of Southern University of Science and Technology, and the Freeze Electron Microscope Center of the Medical College of Zhejiang University.
Paper link：
论文链接
