Structural insights into a dimeric Psb27-photosystem II complex from a cyanobacterium <i>Thermosynechococcus vulcanus</i>
Guoqiang Huang, Yanan Xiao, Xiong Pi, Liang Zhao, Qingjun Zhu, Wenda Wang, Tingyun Kuang, Guangye Han, Sen‐Fang Sui, Jian‐Ren Shen
Abstract
, solved by cryo-electron microscopy. Our structure showed that Psb27 is associated with CP43 at the luminal side, with specific interactions formed between Helix 2 and Helix 3 of Psb27 and a loop region between Helix 3 and Helix 4 of CP43 (loop C) as well as the large, lumen-exposed and hydrophilic E-loop of CP43. The binding of Psb27 imposes some conflicts with the N-terminal region of PsbO and also induces some conformational changes in CP43, CP47, and D2. This makes PsbO unable to bind in the Psb27-PSII. Conformational changes also occurred in D1, PsbE, PsbF, and PsbZ; this, together with the conformational changes occurred in CP43, CP47, and D2, may prevent the binding of PsbU and induce dissociation of PsbJ. This structural information provides important insights into the regulation mechanism of Psb27 in the biogenesis and repair of PSII.