Structural basis for enzymatic photocatalysis in chlorophyll biosynthesis

文献类型： 外文期刊

第一作者： Zhang, Shaowei

作者： Zhang, Shaowei;Heyes, Derren J.;Johannissen, Linus O.;Levy, Colin W.;Hardman, Samantha J. O.;Hoeven, Robin;Sakuma, Michiyo;Hay, Sam;Leys, David;Scrutton, Nigel S.;Feng, Lingling;Zhou, Aiwu;Sun, Wenli;Lin, Min;Cheng, Qi;Liu, Huanting;Yang, Ji;Yu, Xiaolan;Cheng, Qi;Li, Xuemei;Rao, Zihe;Cheng, Qi

作者机构：

期刊名称：NATURE （ 影响因子：49.962； 五年影响因子：54.637 ）

ISSN： 0028-0836

年卷期： 2019 年 574 卷 7780 期

页码：

收录情况： SCI

摘要： The enzyme protochlorophyllide oxidoreductase (POR) catalyses a light-dependent step in chlorophyll biosynthesis that is essential to photosynthesis and, ultimately, all life on Earth(1-3). POR, which is one of three known light-dependent enzymes(4,5), catalyses reduction of the photosensitizer and substrate protochlorophyllide to form the pigment chlorophyllide. Despite its biological importance, the structural basis for POR photocatalysis has remained unknown. Here we report crystal structures of cyanobacterial PORs from Thermosynechococcus elongatus and Synechocystis sp. in their free forms, and in complex with the nicotinamide coenzyme. Our structural models and simulations of the ternary protochlorophyllide-NADPH-POR complex identify multiple interactions in the POR active site that are important for protochlorophyllide binding, photosensitization and photochemical conversion to chlorophyllide. We demonstrate the importance of active-site architecture and protochlorophyllide structure in driving POR photochemistry in experiments using POR variants and protochlorophyllide analogues. These studies reveal how the POR active site facilitates light-driven reduction of protochlorophyllide by localized hydride transfer from NADPH and long-range proton transfer along structurally defined proton-transfer pathways.

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