Binding of the substrate analog methanol in the oxygen-evolving complex of photosystem II in the D1-N87A genetic variant of cyanobacteria

The solar water-splitting protein complex, photosystem II (PSII), catalyzes one of the most energetically demanding reactions in nature by using light energy to drive a catalyst capable of oxidizing water. The water oxidation reaction is catalyzed at the Mn 4 Ca-oxo cluster in the oxygen-evolving co...

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Bibliographic Details
Published in:Faraday discussions 2022-05, Vol.234, p.195-213
Main Authors: Kalendra, Vidmantas, Reiss, Krystle M, Banerjee, Gourab, Ghosh, Ipsita, Baldansuren, Amgalanbaatar, Batista, Victor S, Brudvig, Gary W, Lakshmi, K. V
Format: Article
Language:English
Subjects:
Binding
Chemical reactions
Clusters
Cyanobacteria
Density functional theory
Evolution
Methanol
Oxidation
Oxygen
Quantum mechanics
Substrates
Water splitting
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Summary:The solar water-splitting protein complex, photosystem II (PSII), catalyzes one of the most energetically demanding reactions in nature by using light energy to drive a catalyst capable of oxidizing water. The water oxidation reaction is catalyzed at the Mn 4 Ca-oxo cluster in the oxygen-evolving complex (OEC), which cycles through five light-driven S-state intermediates (S 0 -S 4 ). A detailed mechanism of the reaction remains elusive as it requires knowledge of the delivery and binding of substrate water in the higher S-state intermediates. In this study, we use two-dimensional (2D) hyperfine sublevel correlation spectroscopy, in conjunction with quantum mechanics/molecular mechanics (QM/MM) and density functional theory (DFT), to probe the binding of the substrate analog, methanol, in the S 2 state of the D1-N87A variant of PSII from Synechocystis sp. PCC 6803. The results indicate that the size and specificity of the "narrow" channel is altered in D1-N87A PSII, allowing for the binding of deprotonated 13 C-labeled methanol at the Mn4( iv ) ion of the catalytic cluster in the S 2 state. This has important implications on the mechanistic models for water oxidation in PSII. Two-dimensional 13 C HYSCORE spectroscopy, in conjunction with QM/MM and DFT, indicates that methanol binds to the Mn 4 Ca-oxo cluster in the S 2 state of D1-N87A photosystem II from Synechocystis sp. PCC 6803.
ISSN:1359-6640
1364-5498
DOI:10.1039/d1fd00094b