1
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Macromolecular conformational changes in photosystem II: interaction between structure and function. Biophys Rev 2022; 14:871-886. [DOI: 10.1007/s12551-022-00979-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/02/2022] [Indexed: 01/08/2023] Open
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2
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Guo Y, Messinger J, Kloo L, Sun L. Reversible Structural Isomerization of Nature's Water Oxidation Catalyst Prior to O-O Bond Formation. J Am Chem Soc 2022; 144:11736-11747. [PMID: 35748306 PMCID: PMC9264352 DOI: 10.1021/jacs.2c03528] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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Photosynthetic water
oxidation is catalyzed by a manganese–calcium
oxide cluster, which experiences five “S-states” during
a light-driven reaction cycle. The unique “distorted chair”-like
geometry of the Mn4CaO5(6) cluster shows structural
flexibility that has been frequently proposed to involve “open”
and “closed”-cubane forms from the S1 to
S3 states. The isomers are interconvertible in the S1 and S2 states, while in the S3 state,
the open-cubane structure is observed to dominate inThermosynechococcus elongatus (cyanobacteria) samples.
In this work, using density functional theory calculations, we go
beyond the S3+Yz state to the S3nYz• → S4+Yz step, and report for the first time
that the reversible isomerism, which is suppressed in the S3+Yz state, is fully recovered
in the ensuing S3nYz• state due to the proton release
from a manganese-bound water ligand. The altered coordination strength
of the manganese–ligand facilitates formation of the closed-cubane
form, in a dynamic equilibrium with the open-cubane form. This tautomerism
immediately preceding dioxygen formation may constitute the rate limiting
step for O2 formation, and exert a significant influence
on the water oxidation mechanism in photosystem II.
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Affiliation(s)
- Yu Guo
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Johannes Messinger
- Department of Chemistry, Umeå University, Linnaeus väg 6 (KBC huset), SE-90187 Umeå, Sweden.,Molecular Biomimetics, Department of Chemistry─Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
| | - Lars Kloo
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Licheng Sun
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
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3
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Kato Y, Noguchi T. Redox properties and regulatory mechanism of the iron-quinone electron acceptor in photosystem II as revealed by FTIR spectroelectrochemistry. PHOTOSYNTHESIS RESEARCH 2022; 152:135-151. [PMID: 34985636 DOI: 10.1007/s11120-021-00894-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 12/24/2021] [Indexed: 05/09/2023]
Abstract
Photosystem II (PSII) performs oxidation of water and reduction of plastoquinone through light-induced electron transfer. Electron transfer reactions at individual redox cofactors are controlled by their redox potentials, and the forward and backward electron flows in PSII are regulated by tuning them. It is, thus, crucial to accurately estimate the redox potentials of the cofactors and their shifts by environmental changes to understand the regulatory mechanisms in PSII. Fourier-transform infrared (FTIR) spectroelectrochemistry combined with a light-induced difference technique is a powerful method to investigate the mechanisms of the redox reactions in PSII. In this review, we introduce the methodology and the application of this method in the studies of the iron-quinone complex, which consists of two plastoquinone molecules, QA and QB, and the non-heme iron, on the electron-acceptor side of PSII. It is shown that FTIR spectroelectrochemistry is a useful method not only for estimating the redox potentials but also for detecting the reactions of nearby amino-acid residues coupled with the redox reactions.
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Affiliation(s)
- Yuki Kato
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
| | - Takumi Noguchi
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
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4
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Kato Y, Noguchi T. Effects of Stromal and Lumenal Side Perturbations on the Redox Potential of the Primary Quinone Electron Acceptor Q A in Photosystem II. Biochemistry 2021; 60:3697-3706. [PMID: 34784184 DOI: 10.1021/acs.biochem.1c00624] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The primary quinone electron acceptor QA is a key component in the electron transfer regulation in photosystem II (PSII), and hence accurate estimation of its redox potential, Em(QA-/QA), is crucial in understanding the regulatory mechanism. Although fluorescence detection has been extensively used for monitoring the redox state of QA, it was recently suggested that this method tends to provide a higher Em(QA-/QA) estimate depending on the sample status due to the effect of measuring light [Kato et al. (2019) Biochim. Biophys. Acta 1860, 148082]. In this study, we applied the Fourier transform infrared (FTIR) spectroelectrochemistry, which uses non-reactive infrared light to monitor the redox state of QA, to investigate the effects of stromal- and lumenal-side perturbations on Em(QA-/QA) in PSII. It was shown that replacement of bicarbonate bound to the non-heme iron with formate upshifted Em(QA-/QA) by ∼55 mV, consistent with the previous fluorescence measurement. In contrast, an Em(QA-/QA) difference between binding of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and bromoxynil was found to be ∼30 mV, which is much smaller than the previous estimate, ∼100 mV, by the fluorescence method. This ∼30 mV difference was verified by the decay kinetics of the S2QA- recombination. On the lumenal side, Mn depletion hardly affected the Em(QA-/QA), confirming the previous FTIR result. However, removal of the extrinsic proteins by NaCl or CaCl2 wash downshifted the Em(QA-/QA) by 14-20 mV. These results suggest that electron flow through QA is regulated by changes both on the stromal and lumenal sides of PSII.
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Affiliation(s)
- Yuki Kato
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Takumi Noguchi
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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5
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Kato Y, Ohira A, Nagao R, Noguchi T. Does the water-oxidizing Mn4CaO5 cluster regulate the redox potential of the primary quinone electron acceptor QA in photosystem II? A study by Fourier transform infrared spectroelectrochemistry. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:148082. [DOI: 10.1016/j.bbabio.2019.148082] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 08/31/2019] [Accepted: 09/08/2019] [Indexed: 10/25/2022]
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6
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Abstract
Photosystem II (PSII), the light-driven water/plastoquinone photooxidoreductase, is of central importance in the planetary energy cycle. The product of the reaction, plastohydroquinone (PQH2), is released into the membrane from the QB site, where it is formed. A plastoquinone (PQ) from the membrane pool then binds into the QB site. Despite their functional importance, the thermodynamic properties of the PQ in the QB site, QB, in its different redox forms have received relatively little attention. Here we report the midpoint potentials (Em ) of QB in PSII from Thermosynechococcus elongatus using electron paramagnetic resonance (EPR) spectroscopy: Em QB/QB •- ≈ 90 mV, and Em QB •-/QBH2 ≈ 40 mV. These data allow the following conclusions: 1) The semiquinone, QB •-, is stabilized thermodynamically; 2) the resulting Em QB/QBH2 (∼65 mV) is lower than the Em PQ/PQH2 (∼117 mV), and the difference (ΔE ≈ 50 meV) represents the driving force for QBH2 release into the pool; 3) PQ is ∼50× more tightly bound than PQH2; and 4) the difference between the Em QB/QB •- measured here and the Em QA/QA •- from the literature is ∼234 meV, in principle corresponding to the driving force for electron transfer from QA •- to QB The pH dependence of the thermoluminescence associated with QB •- provided a functional estimate for this energy gap and gave a similar value (≥180 meV). These estimates are larger than the generally accepted value (∼70 meV), and this is discussed. The energetics of QB in PSII are comparable to those in the homologous purple bacterial reaction center.
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7
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Koua FHM. Structural Changes in the Acceptor Site of Photosystem II upon Ca 2+/Sr 2+ Exchange in the Mn 4CaO 5 Cluster Site and the Possible Long-Range Interactions. Biomolecules 2019; 9:biom9080371. [PMID: 31416291 PMCID: PMC6722538 DOI: 10.3390/biom9080371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 08/12/2019] [Indexed: 01/15/2023] Open
Abstract
The Mn4CaO5 cluster site in the oxygen-evolving complex (OEC) of photosystem II (PSII) undergoes structural perturbations, such as those induced by Ca2+/Sr2+ exchanges or Ca/Mn removal. These changes have been known to induce long-range positive shifts (between +30 and +150 mV) in the redox potential of the primary quinone electron acceptor plastoquinone A (QA), which is located 40 Å from the OEC. To further investigate these effects, we reanalyzed the crystal structure of Sr-PSII resolved at 2.1 Å and compared it with the native Ca-PSII resolved at 1.9 Å. Here, we focus on the acceptor site and report the possible long-range interactions between the donor, Mn4Ca(Sr)O5 cluster, and acceptor sites.
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Affiliation(s)
- Faisal Hammad Mekky Koua
- Center for Free Electron Laser Science, Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany.
- National University Biomedical Research Institute, National University-Sudan, Air St. PO Box 3783, Khartoum, Sudan.
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8
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Ghosh I, Banerjee G, Kim CJ, Reiss K, Batista VS, Debus RJ, Brudvig GW. D1-S169A Substitution of Photosystem II Perturbs Water Oxidation. Biochemistry 2019; 58:1379-1387. [DOI: 10.1021/acs.biochem.8b01184] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Ipsita Ghosh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Gourab Banerjee
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Christopher J. Kim
- Department of Biochemistry, University of California, Riverside, California 92521, United States
| | - Krystle Reiss
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Victor S. Batista
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Richard J. Debus
- Department of Biochemistry, University of California, Riverside, California 92521, United States
| | - Gary W. Brudvig
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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9
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Bio-inorganic hybrid photoanodes of photosystem II and ferricyanide-intercalated layered double hydroxide for visible-light-driven water oxidation. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.01.133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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10
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Raven JA. Chloride: essential micronutrient and multifunctional beneficial ion. JOURNAL OF EXPERIMENTAL BOTANY 2017; 38:359-367. [PMID: 28040799 DOI: 10.1093/jxb/erw421] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cl− is an essential micronutrient for oxygenic photolithotrophs. About half of global primary productivity is carried out by oxygenic photolithotrophs exposed to saline waters with Cl− concentrations orders of magnitude higher than that needed to satisfy the micronutrient requirement. The other half of primary productivity involves terrestrial and freshwater glycophytes sometimes in environments containing significantly more Cl− than is needed for the micronutrient requirement, but less than the toxic Cl– concentration for glycophytes. Intracellular Cl− acts in regulation of cell turgor and volume, including that of stomatal and pulvinar nastic movements, is a major ion in streptophyte and ulvophycean action potentials, and is involved in ion currents flowing around apices of pollen tubes and Acetabularia cells. More work is needed on the essentiality of Cl− in these processes, as well as the recent finding that Cl− at 1–5 mol m−3 increases water use efficiency of growth and leaf area in Nicotiana tabacum.
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Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, UK
- School of Plant Biology, University of Western Australia MO84, Stirling Highway. Crawley, WA, Australia
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11
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Derks A, Schaven K, Bruce D. Diverse mechanisms for photoprotection in photosynthesis. Dynamic regulation of photosystem II excitation in response to rapid environmental change. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:468-485. [DOI: 10.1016/j.bbabio.2015.02.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/03/2015] [Accepted: 02/07/2015] [Indexed: 12/26/2022]
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12
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Khan S, Sun JS, Brudvig GW. Cation Effects on the Electron-Acceptor Side of Photosystem II. J Phys Chem B 2015; 119:7722-8. [DOI: 10.1021/jp513035u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Sahr Khan
- Department
of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520-8107, United States
| | - Jennifer S. Sun
- Department
of Molecular, Cellular, and Developmental Biology, Yale University, 219
Prospect Street, New Haven, Connecticut 06520-8114, United States
| | - Gary W. Brudvig
- Department
of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520-8107, United States
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13
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Lambreva MD, Russo D, Polticelli F, Scognamiglio V, Antonacci A, Zobnina V, Campi G, Rea G. Structure/function/dynamics of photosystem II plastoquinone binding sites. Curr Protein Pept Sci 2015; 15:285-95. [PMID: 24678671 PMCID: PMC4030317 DOI: 10.2174/1389203715666140327104802] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 11/22/2013] [Accepted: 03/16/2014] [Indexed: 11/22/2022]
Abstract
Photosystem II (PSII)
continuously attracts the attention of researchers aiming to unravel the riddle
of its functioning and efficiency fundamental for all life on Earth. Besides, an
increasing number of biotechnological applications have been envisaged
exploiting and mimicking the unique properties of this macromolecular
pigment-protein complex. The PSII organization and working principles have
inspired the design of electrochemical water splitting schemes and charge
separating triads in energy storage systems as well as biochips and sensors for
environmental, agricultural and industrial screening of toxic compounds. An
intriguing opportunity is the development of sensor devices, exploiting native
or manipulated PSII complexes or ad hoc synthesized polypeptides
mimicking the PSII reaction centre proteins as bio-sensing elements. This review
offers a concise overview of the recent improvements in the understanding of
structure and function of PSII donor side, with focus on the interactions of the
plastoquinone cofactors with the surrounding environment and operational
features. Furthermore, studies focused on photosynthetic proteins
structure/function/dynamics and computational analyses aimed at rational design
of high-quality bio-recognition elements in biosensor devices are discussed.
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Affiliation(s)
| | | | | | | | | | | | | | - Giuseppina Rea
- Institute of Crystallography, National Research Council, Monterotondo, Italy.
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14
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Sugiura M, Boussac A. Variants of photosystem II D1 protein in Thermosynechococcus elongatus. RESEARCH ON CHEMICAL INTERMEDIATES 2014. [DOI: 10.1007/s11164-014-1828-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Kato Y, Noguchi T. Long-Range Interaction between the Mn4CaO5 Cluster and the Non-heme Iron Center in Photosystem II as Revealed by FTIR Spectroelectrochemistry. Biochemistry 2014; 53:4914-23. [DOI: 10.1021/bi500549b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Yuki Kato
- Division of Material Science,
Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Takumi Noguchi
- Division of Material Science,
Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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16
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Zhang Y, Magdaong N, Frank HA, Rusling JF. Protein film voltammetry and co-factor electron transfer dynamics in spinach photosystem II core complex. PHOTOSYNTHESIS RESEARCH 2014; 120:153-167. [PMID: 23625504 DOI: 10.1007/s11120-013-9831-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 04/15/2013] [Indexed: 06/02/2023]
Abstract
Direct protein film voltammetry (PFV) was used to investigate the redox properties of the photosystem II (PSII) core complex from spinach. The complex was isolated using an improved protocol not used previously for PFV. The PSII core complex had high oxygen-evolving capacity and was incorporated into thin lipid and polyion films. Three well-defined reversible pairs of reduction and oxidation voltammetry peaks were observed at 4 °C in the dark. Results were similar in both types of films, indicating that the environment of the PSII-bound cofactors was not influenced by film type. Based on comparison with various control samples including Mn-depleted PSII, peaks were assigned to chlorophyll a (Chl a) (Em = -0.47 V, all vs. NHE, at pH 6), quinones (-0.12 V), and the manganese (Mn) cluster (Em = 0.18 V). PFV of purified iron heme protein cytochrome b-559 (Cyt b-559), a component of PSII, gave a partly reversible peak pair at 0.004 V that did not have a potential similar to any peaks observed from the intact PSII core complex. The closest peak in PSII to 0.004 V is the 0.18 V peak that was found to be associated with a two-electron process, and thus is inconsistent with iron heme protein voltammetry. The -0.47 V peak had a peak potential and peak potential-pH dependence similar to that found for purified Chl a incorporated into DMPC films. The midpoint potentials reported here may differ to various extents from previously reported redox titration data due to the influence of electrode double-layer effects. Heterogeneous electron transfer (hET) rate constants were estimated by theoretical fitting and digital simulations for the -0.47 and 0.18 V peaks. Data for the Chl a peaks were best fit to a one-electron model, while the peak assigned to the Mn cluster was best fit by a two-electron/one-proton model.
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Affiliation(s)
- Yun Zhang
- Department of Chemistry, University of Connecticut, Storrs, CT, 06269-3060, USA
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17
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Sugiura M, Boussac A. Some Photosystem II properties depending on the D1 protein variants in Thermosynechococcus elongatus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1427-34. [PMID: 24388918 DOI: 10.1016/j.bbabio.2013.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/17/2013] [Accepted: 12/25/2013] [Indexed: 10/25/2022]
Abstract
Cyanobacteria have multiple psbA genes encoding PsbA, the D1 reaction center protein of the Photosystem II complex which bears together with PsbD, the D2 protein, most of the cofactors involved in electron transfer reactions. The thermophilic cyanobacterium Thermosynechococcus elongatus has three psbA genes differently expressed depending on the environmental conditions. Among the 344 residues constituting each of the 3 possible PsbA variants there are 21 substitutions between PsbA1 and PsbA3, 31 between PsbA1 and PsbA2 and 27 between PsbA2 and PsbA3. In this review, we summarize the changes already identified in the properties of the redox cofactors depending on the D1 variant constituting Photosystem II in T. elongatus. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.
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Affiliation(s)
- Miwa Sugiura
- Proteo-science Research Center, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan; PRESTO, Japan Science and Technology Agency (JST), 4-1-8, Honcho, Kawauchi, Saitama 332-0012, Japan.
| | - Alain Boussac
- iBiTec-S, CNRS UMR 8221, CEA Saclay, 91191 Gif-sur-Yvette, France.
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18
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Sugiura M, Azami C, Koyama K, Rutherford AW, Rappaport F, Boussac A. Modification of the pheophytin redox potential in Thermosynechococcus elongatus Photosystem II with PsbA3 as D1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:139-48. [DOI: 10.1016/j.bbabio.2013.09.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 09/12/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022]
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19
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The Tll0287 protein is a hemoprotein associated with the PsbA2-Photosystem II complex in Thermosynechococcus elongatus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:1174-82. [DOI: 10.1016/j.bbabio.2013.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 05/27/2013] [Accepted: 06/05/2013] [Indexed: 12/14/2022]
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20
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Müh F, Zouni A. The nonheme iron in photosystem II. PHOTOSYNTHESIS RESEARCH 2013; 116:295-314. [PMID: 24077892 DOI: 10.1007/s11120-013-9926-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/17/2013] [Indexed: 06/02/2023]
Abstract
Photosystem II (PSII), the light-driven water:plastoquinone (PQ) oxidoreductase of oxygenic photosynthesis, contains a nonheme iron (NHI) at its electron acceptor side. The NHI is situated between the two PQs QA and QB that serve as one-electron transmitter and substrate of the reductase part of PSII, respectively. Among the ligands of the NHI is a (bi)carbonate originating from CO2, the substrate of the dark reactions of oxygenic photosynthesis. Based on recent advances in the crystallography of PSII, we review the structure of the NHI in PSII and discuss ideas concerning its function and the role of bicarbonate along with a comparison to the reaction center of purple bacteria and other enzymes containing a mononuclear NHI site.
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21
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Vinyard DJ, Ananyev GM, Charles Dismukes G. Photosystem II: The Reaction Center of Oxygenic Photosynthesis. Annu Rev Biochem 2013; 82:577-606. [DOI: 10.1146/annurev-biochem-070511-100425] [Citation(s) in RCA: 279] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David J. Vinyard
- Department of Chemistry and Chemical Biology and the Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854; ,
- Department of Chemistry, Princeton University, Princeton, New Jersey 08540;
| | - Gennady M. Ananyev
- Department of Chemistry and Chemical Biology and the Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854; ,
| | - G. Charles Dismukes
- Department of Chemistry and Chemical Biology and the Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854; ,
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22
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Boussac A, Rappaport F, Brettel K, Sugiura M. Charge recombination in S(n)Tyr(Z)(•)Q(A)(-•) radical pairs in D1 protein variants of Photosystem II: long range electron transfer in the Marcus inverted region. J Phys Chem B 2013; 117:3308-14. [PMID: 23448315 DOI: 10.1021/jp400337j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Charge recombination in the light-induced radical pair SnTyrZ(•)QA(-•) in Photosystem II (PSII) from Thermosynechococcus elongatus has been studied at cryogenic temperatures by time-resolved EPR for different configurations of PSII that are expected to affect the driving force of the reaction (oxidation states S0, S1, or S2 of the Mn4CaO5 cluster; PsbA1, PsbA2, or PsbA3 as D1 protein). The kinetics were independent of temperature in the studied range from 4.2 to 50 K and were not affected by exchange of H2O for D2O, consistent with single-step electron tunneling over the distance of ∼32 Å without any repopulation through Boltzmann equilibration of intermediates lying higher in energy. In PsbA1-PSII, the charge recombinations in the radical pairs SnTyrZ(•)QA(-•) (ket = 3.4 × 10(-3) s(-1) for S1) were slower than in PsbA3-PSII despite an expected lower driving force owing to a downshifted Em(QA/QA(-•)) in PsbA1-PSII. Conversely, the reaction was slower in the presence of S2 than in the presence of S1, despite an expected larger driving force due to an upshifted Em(TyrZ(•)/TyrZ) in S2. These observations indicate that the charge recombination occurs in the Marcus inverted region. Assuming that the driving force of the reaction (-ΔG(0) ≈ 1.2 eV at room temperature for S1) does not vary strongly with temperature, the data indicate an optimal electron transfer rate (for a hypothetical -ΔG(0) = λ) substantially faster than would be predicted from extrapolation of room temperature intraprotein ET rates over shorter distances. Possible origins of this deviation are discussed, including a possible enhancement of the electronic coupling of TyrZ(•) and QA(-•) by aromatic cofactors located in between. Observed similar S1TyrZ(•)QA(-•) charge recombinations in PsbA2-PSII and PsbA3-PSII predict that Em(QA/QA(-•)) in PsbA2-PSII is similar to that in PsbA3-PSII.
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Affiliation(s)
- Alain Boussac
- iBiTec-S, CNRS UMR 8221, CEA Saclay, 91191 Gif-sur-Yvette, France.
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Vinyard DJ, Gimpel J, Ananyev GM, Cornejo MA, Golden SS, Mayfield SP, Dismukes GC. Natural variants of photosystem II subunit D1 tune photochemical fitness to solar intensity. J Biol Chem 2012; 288:5451-62. [PMID: 23271739 DOI: 10.1074/jbc.m112.394668] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Photosystem II (PSII) is composed of six core polypeptides that make up the minimal unit capable of performing the primary photochemistry of light-driven charge separation and water oxidation in all oxygenic phototrophs. The D1 subunit of this complex contains most of the ligating amino acid residues for the Mn(4)CaO(5) core of the water-oxidizing complex (WOC). Most cyanobacteria have 3-5 copies of the psbA gene coding for at least two isoforms of D1, whereas algae and plants have only one isoform. Synechococcus elongatus PCC 7942 contains two D1 isoforms; D1:1 is expressed under low light conditions, and D1:2 is up-regulated in high light or stress conditions. Using a heterologous psbA expression system in the green alga Chlamydomonas reinhardtii, we have measured growth rate, WOC cycle efficiency, and O(2) yield as a function of D1:1, D1:2, or the native algal D1 isoform. D1:1-PSII cells outcompete D1:2-PSII cells and accumulate more biomass in light-limiting conditions. However, D1:2-PSII cells easily outcompete D1:1-PSII cells at high light intensities. The native C. reinhardtii-PSII WOC cycles less efficiently at all light intensities and produces less O(2) than either cyanobacterial D1 isoform. D1:2-PSII makes more O(2) per saturating flash than D1:1-PSII, but it exhibits lower WOC cycling efficiency at low light intensities due to a 40% faster charge recombination rate in the S(3) state. These functional advantages of D1:1-PSII and D1:2-PSII at low and high light regimes, respectively, can be explained by differences in predicted redox potentials of PSII electron acceptors that control kinetic performance.
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Affiliation(s)
- David J Vinyard
- Department of Chemistry and Chemical Biology, State University of New Jersey, Piscataway, New Jersey 08854, USA
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