Energetics of proton release on the first oxidation step in the water-oxidizing enzyme
Author(s)
Saito, K
Rutherford, AW
Ishikita, H
Type
Journal Article
Abstract
In photosystem II (PSII), the Mn4CaO5 cluster catalyses the water splitting reaction. The crystal structure of PSII shows the presence of a hydrogen-bonded water molecule directly linked to O4. Here we show the detailed properties of the H-bonds associated with the Mn4CaO5 cluster using a quantum mechanical/molecular mechanical approach. When O4 is taken as a μ-hydroxo bridge acting as a hydrogen-bond donor to water539 (W539), the S0 redox state best describes the unusually short O4–OW539 distance (2.5 Å) seen in the crystal structure. We find that in S1, O4 easily releases the proton into a chain of eight strongly hydrogen-bonded water molecules. The corresponding hydrogen-bond network is absent for O5 in S1. The present study suggests that the O4-water chain could facilitate the initial deprotonation event in PSII. This unexpected insight is likely to be of real relevance to mechanistic models for water oxidation.
Date Issued
2015-10-07
Date Acceptance
2015-08-26
Citation
Nature Communications, 2015, 6, pp.1-10
ISSN
2041-1723
Publisher
Nature Publishing Group
Start Page
1
End Page
10
Journal / Book Title
Nature Communications
Volume
6
Copyright Statement
This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
License URL
Sponsor
Biotechnology and Biological Sciences Research Council (BBSRC)
Grant Number
BB/K002627/1
Subjects
Science & Technology
Multidisciplinary Sciences
Science & Technology - Other Topics
OXYGEN-EVOLVING COMPLEX
PHOTOSYSTEM-II
SUBSTRATE WATER
CRYSTAL-STRUCTURE
1.9 ANGSTROM
ELECTRONIC-STRUCTURE
MANGANESE CATALASE
HYDROGEN-BONDS
BINDING-SITES
MN4CA COMPLEX
Crystallography, X-Ray
Hydrogen Bonding
Manganese
Models, Molecular
Oxidation-Reduction
Photosystem II Protein Complex
Protons
Synechococcus
Water
MD Multidisciplinary
Publication Status
Published
Article Number
8448
Date Publish Online
2015-10-07