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Structural basis for enzymatic photocatalysis in chlorophyll biosynthesis

DOI: 10.1038/s41586-019-1685-2 DOI Help

Authors: Shaowei Zhang (The University of Manchester) , Derren J. Heyes (The University of Manchester) , Lingling Feng (Shanghai Jiao Tong University School of Medicine) , Wenli Sun (Biotechnology Research Institute, Chinese Academy of Agricultural Sciences) , Linus O. Johannissen (Manchester Institute of Biotechnology, The University of Manchester) , Huanting Liu (Qi Institute) , Colin Levy (Manchester Institute of Biotechnology, The University of Manchester) , Xuemei Li (Institute of Biophysics, Chinese Academy of Sciences) , Ji Yang (Qi Institute) , Xiaolan Yu (Qi Institute) , Min Lin (Biotechnology Research Institute, Chinese Academy of Agricultural Sciences) , Samantha J. O. Hardman (Manchester Institute of Biotechnology, The University of Manchester) , Robin Hoeven (Manchester Institute of Biotechnology, The University of Manchester) , Michiyo Sakuma (Manchester Institute of Biotechnology, The University of Manchester) , Sam Hay (Manchester Institute of Biotechnology, The University of Manchester) , David Leys (Manchester Institute of Biotechnology, The University of Manchester) , Zihe Rao (Institute of Biophysics, Chinese Academy of Sciences) , Aiwu Zhou (Shanghai Jiao Tong University School of Medicine) , Qi Cheng (Biotechnology Research Institute, Chinese Academy of Agricultural Sciences; Qi Institute; Zhejiang University of Technology) , Nigel S. Scrutton (Manchester Institute of Biotechnology, The University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature , VOL 6

State: Published (Approved)
Published: October 2019
Diamond Proposal Number(s): 8997 , 12788

Abstract: The enzyme protochlorophyllide oxidoreductase (POR) catalyses a light-dependent step in chlorophyll biosynthesis that is essential to photosynthesis and, ultimately, all life on Earth1,2,3. POR, which is one of three known light-dependent enzymes4,5, 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.

Diamond Keywords: Photosynthesis; Photocatalysis; Enzymes

Subject Areas: Biology and Bio-materials, Chemistry


Instruments: I03-Macromolecular Crystallography , I04-Macromolecular Crystallography

Other Facilities: Shanghai Synchrotron Radiation Facility

Added On: 29/10/2019 11:18

Discipline Tags:

Biochemistry Catalysis Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)