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Title: Substitution of the D1-Asn 87 site in photosystem II of cyanobacteria mimics the chloride-binding characteristics of spinach photosystem II

Abstract

Photoinduced water oxidation at the O2-evolving complex (OEC) of photosystem II (PSII) is a complex process involving a tetramanganese-calcium cluster that is surrounded by a hydrogen-bonded network of water molecules, chloride ions, and amino acid residues. Although the structure of the OEC has remained conserved over eons of evolution, significant differences in the chloride-binding characteristics exist between cyanobacteria and higher plants. An analysis of amino acid residues in and around the OEC has identified residue 87 in the D1 subunit as the only significant difference between PSII in cyanobacteria and higher plants. We substituted the D1-Asn87 residue in the cyanobacterium Synechocystis sp. PCC 6803 (wildtype) with alanine, present in higher plants, or with aspartic acid. We studied PSII core complexes purified from D1-N87A and D1-N87D variant strains to probe the function of the D1-Asn87 residue in the water-oxidation mechanism. EPR spectra of the S2 state and flash-induced FTIR spectra of both D1-N87A and D1-N87D PSII core complexes exhibited characteristics similar to those of wildtype Synechocystis PSII core complexes. However, flash-induced O2-evolution studies revealed a decreased cycling efficiency of the D1-N87D variant, whereas the cycling efficiency of the D1-N87A PSII variant was similar to that of wildtype PSII. Steady-state O2-evolution activitymore » assays revealed that substitution of the D1 residue at position 87 with alanine perturbs the chloride-binding site in the proton-exit channel. These findings provide new insight into the role of the D1-Asn87 site in the water-oxidation mechanism and explain the difference in the chloride-binding properties of cyanobacterial and higher-plant PSII.« less

Authors:
; ; ; ORCiD logo; ORCiD logo
Publication Date:
Research Org.:
Yale Univ., New Haven, CT (United States); Univ. of California, Riverside, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1540308
Grant/Contract Number:  
FG02-05ER15646; SC0005291
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Biological Chemistry
Additional Journal Information:
Journal Volume: 293; Journal Issue: 7; Journal ID: ISSN 0021-9258
Publisher:
American Society for Biochemistry and Molecular Biology
Country of Publication:
United States
Language:
English
Subject:
Biochemistry & Molecular Biology

Citation Formats

Banerjee, Gourab, Ghosh, Ipsita, Kim, Christopher J., Debus, Richard J., and Brudvig, Gary W. Substitution of the D1-Asn 87 site in photosystem II of cyanobacteria mimics the chloride-binding characteristics of spinach photosystem II. United States: N. p., 2017. Web. doi:10.1074/jbc.m117.813170.
Banerjee, Gourab, Ghosh, Ipsita, Kim, Christopher J., Debus, Richard J., & Brudvig, Gary W. Substitution of the D1-Asn 87 site in photosystem II of cyanobacteria mimics the chloride-binding characteristics of spinach photosystem II. United States. doi:10.1074/jbc.m117.813170.
Banerjee, Gourab, Ghosh, Ipsita, Kim, Christopher J., Debus, Richard J., and Brudvig, Gary W. Wed . "Substitution of the D1-Asn 87 site in photosystem II of cyanobacteria mimics the chloride-binding characteristics of spinach photosystem II". United States. doi:10.1074/jbc.m117.813170. https://www.osti.gov/servlets/purl/1540308.
@article{osti_1540308,
title = {Substitution of the D1-Asn 87 site in photosystem II of cyanobacteria mimics the chloride-binding characteristics of spinach photosystem II},
author = {Banerjee, Gourab and Ghosh, Ipsita and Kim, Christopher J. and Debus, Richard J. and Brudvig, Gary W.},
abstractNote = {Photoinduced water oxidation at the O2-evolving complex (OEC) of photosystem II (PSII) is a complex process involving a tetramanganese-calcium cluster that is surrounded by a hydrogen-bonded network of water molecules, chloride ions, and amino acid residues. Although the structure of the OEC has remained conserved over eons of evolution, significant differences in the chloride-binding characteristics exist between cyanobacteria and higher plants. An analysis of amino acid residues in and around the OEC has identified residue 87 in the D1 subunit as the only significant difference between PSII in cyanobacteria and higher plants. We substituted the D1-Asn87 residue in the cyanobacterium Synechocystis sp. PCC 6803 (wildtype) with alanine, present in higher plants, or with aspartic acid. We studied PSII core complexes purified from D1-N87A and D1-N87D variant strains to probe the function of the D1-Asn87 residue in the water-oxidation mechanism. EPR spectra of the S2 state and flash-induced FTIR spectra of both D1-N87A and D1-N87D PSII core complexes exhibited characteristics similar to those of wildtype Synechocystis PSII core complexes. However, flash-induced O2-evolution studies revealed a decreased cycling efficiency of the D1-N87D variant, whereas the cycling efficiency of the D1-N87A PSII variant was similar to that of wildtype PSII. Steady-state O2-evolution activity assays revealed that substitution of the D1 residue at position 87 with alanine perturbs the chloride-binding site in the proton-exit channel. These findings provide new insight into the role of the D1-Asn87 site in the water-oxidation mechanism and explain the difference in the chloride-binding properties of cyanobacterial and higher-plant PSII.},
doi = {10.1074/jbc.m117.813170},
journal = {Journal of Biological Chemistry},
number = 7,
volume = 293,
place = {United States},
year = {2017},
month = {12}
}

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