Nature Communications, 19 June, 2024, DOI：https://doi.org/10.1038/s41467-024-49532-2

Structural basis for an early stage of the photosystem II repair cycle in Chlamydomonas reinhardtii

Anjie Li, Tingting You, Xiaojie Pang, Yidi Wang, Lijin Tian, Xiaobo Li & Zhenfeng Liu

Abstract

Photosystem II (PSII) catalyzes water oxidation and plastoquinone reduction by utilizing light energy. It is highly susceptible to photodamage under high-light conditions and the damaged PSII needs to be restored through a process known as the PSII repair cycle. The detailed molecular mechanism underlying the PSII repair process remains mostly elusive. Here, we report biochemical and structural features of a PSII-repair intermediate complex, likely arrested at an early stage of the PSII repair process in the green alga Chlamydomonas reinhardtii. The complex contains three protein factors associated with a damaged PSII core, namely Thylakoid Enriched Factor 14 (TEF14), Photosystem II Repair Factor 1 (PRF1), and Photosystem II Repair Factor 2 (PRF2). TEF14, PRF1 and PRF2 may facilitate the release of the manganese-stabilizing protein PsbO, disassembly of peripheral light-harvesting complexes from PSII and blockage of the Q_B site, respectively. Moreover, an α-tocopherol quinone molecule is located adjacent to the heme group of cytochrome b₅₅₉, potentially fulfilling a photoprotective role by preventing the generation of reactive oxygen species.

Article link：https://www.nature.com/articles/s41467-024-49532-2