<br>触生体光系统 I 光捕获超复合物组装和能量转移的结构见解,Proceedings of the National Academy of Sciences of the United States of America

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触生体光系统 I 光捕获超复合物组装和能量转移的结构见解
Proceedings of the National Academy of Sciences of the United States of America ( IF 9.4 ) Pub Date : 2024-12-06 , DOI: 10.1073/pnas.2413678121
Fei-Yu He, Long-Sheng Zhao, Xin-Xiao Qu, Kang Li, Jian-Ping Guo, Fang Zhao, Ning Wang, Bing-Yue Qin, Xiu-Lan Chen, Jun Gao, Lu-Ning Liu, Yu-Zhong Zhang

触生菌门代表一个主要的分类群，其质体来源于红藻的初级质体。在这里，我们阐明了来自触生植物 Isochrysis galbana 的光系统 I – 光捕获复合物 I （PSI-LHCI）超复合物的冷冻电子显微镜结构。PSI 核心由 12 个亚基组成，这些亚基的进化与红藻和隐生植物不同，它失去了 PsaO 亚基，同时掺入了硅藻和甲藻中不存在的 PsaK 亚基。PSI 核心被 22 个岩藻黄质-叶绿素 a/c 结合光捕获天线蛋白（iFCPI）包围，形成三层天线排列。此外，在 I. galbana PSI-iFCPI 中测定了尚未在任何其他先前表征的 PSI-LHCI 超复合物中鉴定的色素结合亚基 L iFP，可能促进了外周 iFCPI 和 PSI 核心之间的相互作用和能量转移。通过计算模拟计算激发能量传递速率表明，PSI-iFCPI 内形成的复杂颜料网络确保了激发能的有效传递。总体而言，我们的研究为理解触生体 PSI-iFCPI 中的光捕获和能量转移机制提供了坚实的结构基础，并为红系 PSI-LHCIs 的进化和结构变化提供了见解。

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Structural insights into the assembly and energy transfer of haptophyte photosystem I–light-harvesting supercomplex

Haptophyta represents a major taxonomic group, with plastids derived from the primary plastids of red algae. Here, we elucidated the cryoelectron microscopy structure of the photosystem I–light-harvesting complex I (PSI–LHCI) supercomplex from the haptophyte Isochrysis galbana . The PSI core comprises 12 subunits, which have evolved differently from red algae and cryptophytes by losing the PsaO subunit while incorporating the PsaK subunit, which is absent in diatoms and dinoflagellates. The PSI core is encircled by 22 fucoxanthin-chlorophyll a / c -binding light-harvesting antenna proteins (iFCPIs) that form a trilayered antenna arrangement. Moreover, a pigment-binding subunit, L iFP , which has not been identified in any other previously characterized PSI–LHCI supercomplexes, was determined in I. galbana PSI–iFCPI, presumably facilitating the interactions and energy transfer between peripheral iFCPIs and the PSI core. Calculation of excitation energy transfer rates by computational simulations revealed that the intricate pigment network formed within PSI–iFCPI ensures efficient transfer of excitation energy. Overall, our study provides a solid structural foundation for understanding the light-harvesting and energy transfer mechanisms in haptophyte PSI–iFCPI and provides insights into the evolution and structural variations of red-lineage PSI–LHCIs.

更新日期：2024-12-06

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