Cryo-electron microscopy reveals hydrogen positions and water networks in photosystem II

• 成果类型: Article
• 署名作者: Hussein, Rana; Graca, Andre; Forsman, Jack; Aydin, A. Orkun; Hall, Michael; Gaetcke, Julia; Chernev, Petko; Wendler, Petra; Dobbek, Holger; Messinger, Johannes; Zouni, Athina; Schroder, Wolfgang P.
• 署名单位: Humboldt University of Berlin; Umea University; Uppsala University; University of Potsdam; Umea University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-13844
• DOI: 10.1126/science.adn6541
• 发表日期: 2024-06-21
• 页码: 1349-1355
• 关键词: artificial photosynthesis; electron-transfer; cryo-em; oxygen; refinement; principles; mechanism; complex; o-2

摘要

Photosystem II starts the photosynthetic electron transport chain that converts solar energy into chemical energy and thus sustains life on Earth. It catalyzes two chemical reactions: water oxidation to molecular oxygen and plastoquinone reduction. Coupling of electron and proton transfer is crucial for efficiency; however, the molecular basis of these processes remains speculative owing to uncertain water binding sites and the lack of experimentally determined hydrogen positions. We thus collected high-resolution cryo-electron microscopy data of fully hydrated photosystem II from the thermophilic cyanobacterium Thermosynechococcus vestitus to a final resolution of 1.71 angstroms. The structure reveals several previously undetected partially occupied water binding sites and more than half of the hydrogen and proton positions. This clarifies the pathways of substrate water binding and plastoquinone B protonation.