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Determining the Electronic Structure of Paramagnetic Intermediates in membrane proteins: A high-resolution 2D 1H hyperfine sublevel correlation study of the redox-active tyrosines of photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183422. [DOI: 10.1016/j.bbamem.2020.183422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 06/19/2020] [Accepted: 07/15/2020] [Indexed: 01/26/2023]
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2
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Chrysina M, de Mendonça Silva JC, Zahariou G, Pantazis DA, Ioannidis N. Proton Translocation via Tautomerization of Asn298 During the S 2-S 3 State Transition in the Oxygen-Evolving Complex of Photosystem II. J Phys Chem B 2019; 123:3068-3078. [PMID: 30888175 PMCID: PMC6727346 DOI: 10.1021/acs.jpcb.9b02317] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
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In biological water oxidation, a
redox-active tyrosine residue
(D1-Tyr161 or YZ) mediates electron transfer between the
Mn4CaO5 cluster of the oxygen-evolving complex
and the charge-separation site of photosystem II (PSII), driving the
cluster through progressively higher oxidation states Si (i = 0–4). In contrast to
lower S-states (S0, S1), in higher S-states
(S2, S3) of the Mn4CaO5 cluster, YZ cannot be oxidized at cryogenic temperatures
due to the accumulation of positive charge in the S1 →
S2 transition. However, oxidation of YZ by illumination
of S2 at 77–190 K followed by rapid freezing and
charge recombination between YZ• and
the plastoquinone radical QA•– allows trapping of an S2 variant, the so-called S2trapped state (S2t), that
is capable of forming YZ• at cryogenic
temperature. To identify the differences between the S2 and S2t states, we used the S2tYZ• intermediate as a probe for
the S2t state and followed the S2tYZ•/QA•– recombination kinetics at 10 K using time-resolved electron paramagnetic
resonance spectroscopy in H2O and D2O. The results
show that while S2tYZ•/QA•– recombination can be described
as pure electron transfer occurring in the Marcus inverted region,
the S2t → S2 reversion depends
on proton rearrangement and exhibits a strong kinetic isotope effect.
This suggests that YZ oxidation in the S2t state is facilitated by favorable proton redistribution in
the vicinity of YZ, most likely within the hydrogen-bonded
YZ–His190–Asn298 triad. Computational models
show that tautomerization of Asn298 to its imidic acid form enables
proton translocation to an adjacent asparagine-rich cavity of water
molecules that functions as a proton reservoir and can further participate
in proton egress to the lumen.
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Affiliation(s)
- Maria Chrysina
- Institute of Nanoscience & Nanotechnology , NCSR "Demokritos" , Athens 15310 , Greece.,Max-Planck-Institut für Chemische Energiekonversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Juliana Cecília de Mendonça Silva
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany.,Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany
| | - Georgia Zahariou
- Institute of Nanoscience & Nanotechnology , NCSR "Demokritos" , Athens 15310 , Greece
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany
| | - Nikolaos Ioannidis
- Institute of Nanoscience & Nanotechnology , NCSR "Demokritos" , Athens 15310 , Greece
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3
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Calcium, conformational selection, and redox-active tyrosine YZ in the photosynthetic oxygen-evolving cluster. Proc Natl Acad Sci U S A 2018; 115:5658-5663. [PMID: 29752381 DOI: 10.1073/pnas.1800758115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In Photosystem II (PSII), YZ (Tyr161D1) participates in radical transfer between the chlorophyll donor and the Mn4CaO5 cluster. Under flashing illumination, the metal cluster cycles among five Sn states, and oxygen is evolved from water. The essential YZ is transiently oxidized and reduced on each flash in a proton-coupled electron transfer (PCET) reaction. Calcium is required for function. Of reconstituted divalent ions, only strontium restores oxygen evolution. YZ is predicted to hydrogen bond to calcium-bound water and to His190D1 in PSII structures. Here, we report a vibrational spectroscopic study of YZ radical and singlet in the presence of the metal cluster. The S2 state is trapped by illumination at 190 K; flash illumination then generates the S2YZ radical. Using reaction-induced FTIR spectroscopy and divalent ion depletion/substitution, we identify calcium-sensitive tyrosyl radical and tyrosine singlet bands in the S2 state. In calcium-containing PSII, two CO stretching bands are detected at 1,503 and 1,478 cm-1 These bands are assigned to two different radical conformers in calcium-containing PSII. At pH 6.0, the 1,503-cm-1 band shifts to 1,507 cm-1 in strontium-containing PSII, and the band is reduced in intensity in calcium-depleted PSII. These effects are consistent with a hydrogen-bonding interaction between the calcium site and one conformer of radical YZ. Analysis of the amide I region indicates that calcium selects for a PCET reaction in a subset of the YZ conformers, which are trapped in the S2 state. These results support the interpretation that YZ undergoes a redox-coupled conformational change, which is calcium dependent.
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Beal NJ, Corry TA, O'Malley PJ. A Comparison of Experimental and Broken Symmetry Density Functional Theory (BS-DFT) Calculated Electron Paramagnetic Resonance (EPR) Parameters for Intermediates Involved in the S 2 to S 3 State Transition of Nature's Oxygen Evolving Complex. J Phys Chem B 2018; 122:1394-1407. [PMID: 29300480 DOI: 10.1021/acs.jpcb.7b10843] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A broken symmetry density functional theory (BS-DFT) magnetic analysis of the S2, S2YZ•, and S3 states of Nature's oxygen evolving complex is performed for both the native Ca and Sr substituted forms. Good agreement with experiment is observed between the tyrosyl calculated g-tensor and 1H hyperfine couplings for the native Ca form. Changes in the hydrogen bonding environment of the tyrosyl radical in S2YZ• caused by Sr substitution lead to notable changes in the calculated g-tensor of the tyrosyl radical. Comparison of calculated and experimental 55Mn hyperfine couplings for the S3 state presently favors an open cubane form of the complex with an additional OH ligand coordinating to MnD. In Ca models, this additional ligation can arise by closed-cubane form deprotonation of the Ca ligand W3 in the S2YZ• state accompanied by spontaneous movement to the vacant Mn coordination site or by addition of an external OH group. For the Sr form, no spontaneous movement of W3 to the vacant Mn coordination site is observed in contrast to the native Ca form, a difference which may lead to the reduced catalytic activity of the Sr substituted form. BS-DFT studies on peroxo models of S3 as indicated by a recent X-ray free electron laser (XFEL) crystallography study give rise to a structural model compatible with experimental data and an S = 3 ground state compatible with EPR studies.
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Affiliation(s)
- Nathan J Beal
- School of Chemistry, The University of Manchester , Manchester M13 9PL, U.K
| | - Thomas A Corry
- School of Chemistry, The University of Manchester , Manchester M13 9PL, U.K
| | - Patrick J O'Malley
- School of Chemistry, The University of Manchester , Manchester M13 9PL, U.K
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5
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Guo Z, Barry BA. Calcium, Ammonia, Redox-Active Tyrosine YZ, and Proton-Coupled Electron Transfer in the Photosynthetic Oxygen-Evolving Complex. J Phys Chem B 2017; 121:3987-3996. [DOI: 10.1021/acs.jpcb.7b01802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Zhanjun Guo
- School of Chemistry and Biochemistry and Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Bridgette A. Barry
- School of Chemistry and Biochemistry and Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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Zahariou G, Ioannidis N. Theoretical study of the EPR spectrum of the S 3TyrZ • metalloradical intermediate state of the O 2-evolving complex of photosystem II. PHOTOSYNTHESIS RESEARCH 2016; 130:417-426. [PMID: 27166961 DOI: 10.1007/s11120-016-0274-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 05/03/2016] [Indexed: 05/21/2023]
Abstract
The intermediates trapped during the transitions between the consecutive S-states of the oxygen-evolving complex (OEC) of photosystem II (PSII) contain the free radical TyrZ• interacting magnetically with the Mn-cluster (Mn4Ca). In this paper, we present a theoretical study of the EPR spectrum of the S3TyrZ• metalloradical intermediate state, which has been recently detected in MeOH-containing PSII preparations. For this analysis, we use two different approximations: the first, simpler one, is the point-dipole approach, where the two interacting spins are the S = 1/2 of TyrZ• and the ground spin state of S = 3 of the OEC being in the S3 state. The second approximation is based on previous proposals indicating that the ground spin state (S G = 3) of the S3 state arises from an antiferromagnetic exchange coupling between the S = 9/2 of the Mn(IV)3CaO4 and the S = 3/2 of the external Mn(IV) of the OEC. Under the above assumption, the second approximation involves three interacting spins, denoted S A(Mn(IV)3Ca) = 9/2, S B(Mn(IV)) = 3/2 and S C(TyrZ•) = 1/2. Accordingly, the tyrosine radical is exposed to dipolar interactions with both fragments of the OEC, while an antiferromagnetic exchange coupling within the "3 + 1" structural motif of the OEC is also considered. By application of the first-point-dipole approach, the inter-spin distance that simulates the experimental spectrum is not consistent with the theoretical models that were recently reported for the OEC in the S3 state. Instead, the recent models are consistent with the results of the analysis that is performed by using the second, more detailed, approach.
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Affiliation(s)
- Georgia Zahariou
- Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", 15310, Athens, Greece.
| | - Nikolaos Ioannidis
- Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", 15310, Athens, Greece
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Barry BA. Reaction dynamics and proton coupled electron transfer: studies of tyrosine-based charge transfer in natural and biomimetic systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:46-54. [PMID: 25260243 DOI: 10.1016/j.bbabio.2014.09.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/27/2014] [Accepted: 09/10/2014] [Indexed: 11/25/2022]
Abstract
In bioenergetic reactions, electrons are transferred long distances via a hopping mechanism. In photosynthesis and DNA synthesis, the aromatic amino acid residue, tyrosine, functions as an intermediate that is transiently oxidized and reduced during long distance electron transfer. At physiological pH values, oxidation of tyrosine is associated with a deprotonation of the phenolic oxygen, giving rise to a proton coupled electron transfer (PCET) reaction. Tyrosine-based PCET reactions are important in photosystem II, which carries out the light-induced oxidation of water, and in ribonucleotide reductase, which reduces ribonucleotides to form deoxynucleotides. Photosystem II contains two redox-active tyrosines, YD (Y160 in the D2 polypeptide) and YZ (Y161 in the D1 polypeptide). YD forms a light-induced stable radical, while YZ functions as an essential charge relay, oxidizing the catalytic Mn₄CaO₅ cluster on each of four photo-oxidation reactions. In Escherichia coli class 1a RNR, the β2 subunit contains the radical initiator, Y122O•, which is reversibly reduced and oxidized in long range electron transfer with the α2 subunit. In the isolated E. coli β2 subunit, Y122O• is a stable radical, but Y122O• is activated for rapid PCET in an α2β2 substrate/effector complex. Recent results concerning the structure and function of YD, YZ, and Y122 are reviewed here. Comparison is made to recent results derived from bioengineered proteins and biomimetic compounds, in which tyrosine-based charge transfer mechanisms have been investigated. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Affiliation(s)
- Bridgette A Barry
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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8
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Carrell TG, Smith PF, Dennes J, Dismukes GC. Entropy and enthalpy contributions to the kinetics of proton coupled electron transfer to the Mn4O4(O2PPh2)6 cubane. Phys Chem Chem Phys 2014; 16:11843-7. [PMID: 24643330 DOI: 10.1039/c3cp55200d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dependence of rate, entropy of activation, and ((1)H/(2)H) kinetic isotope effect for H-atom transfer from a series of p-substituted phenols to cubane Mn4O4L6 (L = O2PPh2) (1) reveals the activation energy to form the transition state is proportional to the phenolic O-H bond dissociation energy. New implications for water oxidation and charge recombination in photosystem II are described.
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Affiliation(s)
- Thomas G Carrell
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA
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Keough JM, Zuniga AN, Jenson DL, Barry BA. Redox control and hydrogen bonding networks: proton-coupled electron transfer reactions and tyrosine Z in the photosynthetic oxygen-evolving complex. J Phys Chem B 2013; 117:1296-307. [PMID: 23346921 DOI: 10.1021/jp3118314] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In photosynthetic oxygen evolution, redox active tyrosine Z (YZ) plays an essential role in proton-coupled electron transfer (PCET) reactions. Four sequential photooxidation reactions are necessary to produce oxygen at a Mn(4)CaO(5) cluster. The sequentially oxidized states of this oxygen-evolving cluster (OEC) are called the S(n) states, where n refers to the number of oxidizing equivalents stored. The neutral radical, YZ•, is generated and then acts as an electron transfer intermediate during each S state transition. In the X-ray structure, YZ, Tyr161 of the D1 subunit, is involved in an extensive hydrogen bonding network, which includes calcium-bound water. In electron paramagnetic resonance experiments, we measured the YZ• recombination rate, in the presence of an intact Mn(4)CaO(5) cluster. We compared the S(0) and S(2) states, which differ in Mn oxidation state, and found a significant difference in the YZ• decay rate (t(1/2) = 3.3 ± 0.3 s in S(0); t(1/2) = 2.1 ± 0.3 s in S(2)) and in the solvent isotope effect (SIE) on the reaction (1.3 ± 0.3 in S(0); 2.1 ± 0.3 in S(2)). Although the YZ site is known to be solvent accessible, the recombination rate and SIE were pH independent in both S states. To define the origin of these effects, we measured the YZ• recombination rate in the presence of ammonia, which inhibits oxygen evolution and disrupts the hydrogen bond network. We report that ammonia dramatically slowed the YZ• recombination rate in the S(2) state but had a smaller effect in the S(0) state. In contrast, ammonia had no significant effect on YD•, the stable tyrosyl radical. Therefore, the alterations in YZ• decay, observed with S state advancement, are attributed to alterations in OEC hydrogen bonding and consequent differences in the YZ midpoint potential/pK(a). These changes may be caused by activation of metal-bound water molecules, which hydrogen bond to YZ. These observations document the importance of redox control in proton-coupled electron transfer reactions.
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Affiliation(s)
- James M Keough
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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Keough JM, Jenson DL, Zuniga AN, Barry BA. Proton coupled electron transfer and redox-active tyrosine Z in the photosynthetic oxygen-evolving complex. J Am Chem Soc 2011; 133:11084-7. [PMID: 21714528 PMCID: PMC3246746 DOI: 10.1021/ja2041139] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Proton coupled electron transfer (PCET) reactions play an essential role in many enzymatic processes. In PCET, redox-active tyrosines may be involved as intermediates when the oxidized phenolic side chain deprotonates. Photosystem II (PSII) is an excellent framework for studying PCET reactions, because it contains two redox-active tyrosines, YD and YZ, with different roles in catalysis. One of the redox-active tyrosines, YZ, is essential for oxygen evolution and is rapidly reduced by the manganese-catalytic site. In this report, we investigate the mechanism of YZ PCET in oxygen-evolving PSII. To isolate YZ(•) reactions, but retain the manganese-calcium cluster, low temperatures were used to block the oxidation of the metal cluster, high microwave powers were used to saturate the YD(•) EPR signal, and YZ(•) decay kinetics were measured with EPR spectroscopy. Analysis of the pH and solvent isotope dependence was performed. The rate of YZ(•) decay exhibited a significant solvent isotope effect, and the rate of recombination and the solvent isotope effect were pH independent from pH 5.0 to 7.5. These results are consistent with a rate-limiting, coupled proton electron transfer (CPET) reaction and are contrasted to results obtained for YD(•) decay kinetics at low pH. This effect may be mediated by an extensive hydrogen-bond network around YZ. These experiments imply that PCET reactions distinguish the two PSII redox-active tyrosines.
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Affiliation(s)
- James M. Keough
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - David L. Jenson
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Ashley N. Zuniga
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Bridgette A. Barry
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
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11
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Barry BA. Proton coupled electron transfer and redox active tyrosines in Photosystem II. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2011; 104:60-71. [PMID: 21419640 PMCID: PMC3164834 DOI: 10.1016/j.jphotobiol.2011.01.026] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 01/25/2011] [Accepted: 01/31/2011] [Indexed: 11/30/2022]
Abstract
In this article, progress in understanding proton coupled electron transfer (PCET) in Photosystem II is reviewed. Changes in acidity/basicity may accompany oxidation/reduction reactions in biological catalysis. Alterations in the proton transfer pathway can then be used to alter the rates of the electron transfer reactions. Studies of the bioenergetic complexes have played a central role in advancing our understanding of PCET. Because oxidation of the tyrosine results in deprotonation of the phenolic oxygen, redox active tyrosines are involved in PCET reactions in several enzymes. This review focuses on PCET involving the redox active tyrosines in Photosystem II. Photosystem II catalyzes the light-driven oxidation of water and reduction of plastoquinone. Photosystem II provides a paradigm for the study of redox active tyrosines, because this photosynthetic reaction center contains two tyrosines with different roles in catalysis. The tyrosines, YZ and YD, exhibit differences in kinetics and midpoint potentials, and these differences may be due to noncovalent interactions with the protein environment. Here, studies of YD and YZ and relevant model compounds are described.
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Affiliation(s)
- Bridgette A Barry
- School of Chemistry and Biochemistry and The Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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Chrysina M, Zahariou G, Sanakis Y, Ioannidis N, Petrouleas V. Conformational changes of the S2YZ* intermediate of the S2 to S3 transition in photosystem II. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2011; 104:72-9. [PMID: 21377376 DOI: 10.1016/j.jphotobiol.2011.02.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 01/18/2011] [Accepted: 02/10/2011] [Indexed: 01/02/2023]
Abstract
The paper extends earlier studies on the S(2)Y(Z)* intermediate that is trapped by illumination in the temperature range 77 K to 190 K of untreated samples poised in the S(2)...Q(A) state. X-band EPR experiments on untreated and glycerol (50% v/v) treated samples at 10 K indicate that the intermediate consists of two components. A wide one with a splitting of ca 170 G, and a narrow one characterized by a splitting of ca 120 G (untreated), or 124 G (glycerol-treated samples). Lower temperatures of illumination in the above temperature range favor the wide component, which at 10 K decays faster than the narrow one. Re-illumination at 10 K after decay of the signal trapped at 77-190 K induces only the narrow component. Rapid scan experiments in the temperature range 77-190 K reveal high resolution spectra of the isolated tyz Z* radical and no evidence of alternative radicals. The two split signals are accordingly assigned to different conformations of the S(2)Y(Z)* intermediate A point-dipole simulation of the spectra yields "effective distances" between the spin densities of Y(Z)* and the Mn(4)Ca center of 5.7 Å for the wide and 6.4 Å for the narrow component. The results are discussed on the basis of a molecular model assuming two sequential proton transfers during oxidation of tyr Z. The wide component is assigned to a transient S(2)Y(Z)* conformation, that forms during the primary proton transfer.
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Affiliation(s)
- Maria Chrysina
- Institute of Materials Science, NCSR Demokritos, Athens 15310, Greece
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Chen G, Allahverdiyeva Y, Aro EM, Styring S, Mamedov F. Electron paramagnetic resonance study of the electron transfer reactions in photosystem II membrane preparations from Arabidopsis thaliana. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:205-15. [DOI: 10.1016/j.bbabio.2010.10.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 10/06/2010] [Accepted: 10/08/2010] [Indexed: 10/18/2022]
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Havelius KGV, Su JH, Han G, Mamedov F, Ho FM, Styring S. The formation of the split EPR signal from the S(3) state of Photosystem II does not involve primary charge separation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1807:11-21. [PMID: 20863810 DOI: 10.1016/j.bbabio.2010.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 09/14/2010] [Accepted: 09/15/2010] [Indexed: 11/16/2022]
Abstract
Metalloradical EPR signals have been found in intact Photosystem II at cryogenic temperatures. They reflect the light-driven formation of the tyrosine Z radical (Y(Z)) in magnetic interaction with the CaMn(4) cluster in a particular S state. These so-called split EPR signals, induced at cryogenic temperatures, provide means to study the otherwise transient Y(Z) and to probe the S states with EPR spectroscopy. In the S(0) and S(1) states, the respective split signals are induced by illumination of the sample in the visible light range only. In the S(3) state the split EPR signal is induced irrespective of illumination wavelength within the entire 415-900nm range (visible and near-IR region) [Su, J. H., Havelius, K. G. V., Ho, F. M., Han, G., Mamedov, F., and Styring, S. (2007) Biochemistry 46, 10703-10712]. An important question is whether a single mechanism can explain the induction of the Split S(3) signal across the entire wavelength range or whether wavelength-dependent mechanisms are required. In this paper we confirm that the Y(Z) radical formation in the S(1) state, reflected in the Split S(1) signal, is driven by P680-centered charge separation. The situation in the S(3) state is different. In Photosystem II centers with pre-reduced quinone A (Q(A)), where the P680-centered charge separation is blocked, the Split S(3) EPR signal could still be induced in the majority of the Photosystem II centers using both visible and NIR (830nm) light. This shows that P680-centered charge separation is not involved. The amount of oxidized electron donors and reduced electron acceptors (Q(A)(-)) was well correlated after visible light illumination at cryogenic temperatures in the S(1) state. This was not the case in the S(3) state, where the Split S(3) EPR signal was formed in the majority of the centers in a pathway other than P680-centered charge separation. Instead, we propose that one mechanism exists over the entire wavelength interval to drive the formation of the Split S(3) signal. The origin for this, probably involving excitation of one of the Mn ions in the CaMn(4) cluster in Photosystem II, is discussed.
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Affiliation(s)
- Kajsa G V Havelius
- Molecular Biomimetrics, Department of Photochemistry and Molecular Sciences, Uppsala University, The Angström Laboratory, Uppsala, Sweden
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Cox N, Ogata H, Stolle P, Reijerse E, Auling G, Lubitz W. A Tyrosyl−Dimanganese Coupled Spin System is the Native Metalloradical Cofactor of the R2F Subunit of the Ribonucleotide Reductase of Corynebacterium ammoniagenes. J Am Chem Soc 2010; 132:11197-213. [DOI: 10.1021/ja1036995] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicholas Cox
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim (Ruhr), Germany, and Institut für Mikrobiologie, Leibniz Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
| | - Hideaki Ogata
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim (Ruhr), Germany, and Institut für Mikrobiologie, Leibniz Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
| | - Patrick Stolle
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim (Ruhr), Germany, and Institut für Mikrobiologie, Leibniz Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
| | - Edward Reijerse
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim (Ruhr), Germany, and Institut für Mikrobiologie, Leibniz Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
| | - Georg Auling
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim (Ruhr), Germany, and Institut für Mikrobiologie, Leibniz Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
| | - Wolfgang Lubitz
- Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim (Ruhr), Germany, and Institut für Mikrobiologie, Leibniz Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
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Low-temperature electron transfer suggests two types of QA in intact photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:339-46. [DOI: 10.1016/j.bbabio.2009.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 12/01/2009] [Accepted: 12/03/2009] [Indexed: 11/23/2022]
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17
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Conversion of the g=4.1 EPR signal to the multiline conformation during the S(2) to S(3) transition of the oxygen evolving complex of Photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:487-93. [PMID: 20083085 DOI: 10.1016/j.bbabio.2010.01.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 01/05/2010] [Accepted: 01/11/2010] [Indexed: 12/21/2022]
Abstract
The oxygen evolving complex of Photosystem II undergoes four light-induced oxidation transitions, S(0)-S(1),...,S(3)-(S(4))S(0) during its catalytic cycle. The oxidizing equivalents are stored at a (Mn)(4)Ca cluster, the site of water oxidation. EPR spectroscopy has yielded valuable information on the S states. S(2) shows a notable heterogeneity with two spectral forms; a g=2 (S=1/2) multiline, and a g=4.1 (S=5/2) signal. These oscillate in parallel during the period-four cycle. Cyanobacteria show only the multiline signal, but upon advancement to S(3) they exhibit the same characteristic g=10 (S=3) absorption with plant preparations, implying that this latter signal results from the multiline configuration. The fate of the g=4.1 conformation during advancement to S(3) is accordingly unknown. We searched for light-induced transient changes in the EPR spectra at temperatures below and above the half-inhibition temperature for the S(2) to S(3) transition (ca 230K). We observed that, above about 220K the g=4.1 signal converts to a multiline form prior to advancement to S(3). We cannot exclude that the conversion results from visible-light excitation of the Mn cluster itself. The fact however, that the conversion coincides with the onset of the S(2) to S(3) transition, suggests that it is triggered by the charge-separation process, possibly the oxidation of tyr Z and the accompanying proton relocations. It therefore appears that a configuration of (Mn)(4)Ca with a low-spin ground state advances to S(3).
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Cox N, Ho FM, Pewnim N, Steffen R, Smith PJ, Havelius KG, Hughes JL, Debono L, Styring S, Krausz E, Pace RJ. The S1 split signal of photosystem II; a tyrosine–manganese coupled interaction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:882-9. [DOI: 10.1016/j.bbabio.2009.03.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 03/26/2009] [Accepted: 03/30/2009] [Indexed: 10/20/2022]
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Ren Y, Zhang C, Bao H, Shen J, Zhao J. Probing tyrosine Z oxidation in Photosystem II core complex isolated from spinach by EPR at liquid helium temperatures. PHOTOSYNTHESIS RESEARCH 2009; 99:127-138. [PMID: 19214772 DOI: 10.1007/s11120-009-9410-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 01/23/2009] [Indexed: 05/27/2023]
Abstract
Tyrosine Z (Tyr(Z)) oxidation observed at liquid helium temperatures provides new insights into the structure and function of Tyr(Z) in active Photosystem II (PSII). However, it has not been reported in PSII core complex from higher plants. Here, we report Tyr(Z) oxidation in the S(1) and S(2) states in PSII core complex from spinach for the first time. Moreover, we identified a 500 G-wide symmetric EPR signal (peak position g = 2.18, trough position g = 1.85) together with the g = 2.03 signal induced by visible light at 10 K in the S(1) state in the PSII core complex. These two signals decay with a similar rate in the dark and both disappear in the presence of 6% methanol. We tentatively assign this new feature to the hyperfine structure of the S(1)Tyr(Z)(*) EPR signal. Furthermore, EPR signals of the S(2) state of the Mn-cluster, the oxidation of the non-heme iron, and the S(1)Tyr(Z)(*) in PSII core complexes and PSII-enriched membranes from spinach are compared, which clearly indicate that both the donor and acceptor sides of the reaction center are undisturbed after the removal of LHCII. These results suggest that the new spinach PSII core complex is suitable for the electron transfer study of PSII at cryogenic temperatures.
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Affiliation(s)
- Yanan Ren
- Laboratory of Photochemistry, Beijing National Laboratory of Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
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McEvoy JP, Brudvig GW. Redox Reactions of the Non-Heme Iron in Photosystem II: An EPR Spectroscopic Study. Biochemistry 2008; 47:13394-403. [DOI: 10.1021/bi8013888] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- James P. McEvoy
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107
| | - Gary W. Brudvig
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107
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Conlan B. Designing photosystem II: molecular engineering of photo-catalytic proteins. PHOTOSYNTHESIS RESEARCH 2008; 98:687-700. [PMID: 18777102 DOI: 10.1007/s11120-008-9355-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 08/11/2008] [Indexed: 05/26/2023]
Abstract
Biological photosynthesis utilizes membrane-bound pigment/protein complexes to convert light into chemical energy through a series of electron-transfer events. In the unique photosystem II (PSII) complex these electron-transfer events result in the oxidation of water to molecular oxygen. PSII is an extremely complex enzyme and in order to exploit its unique ability to convert sunlight into chemical energy it will be necessary to make a minimal model. Here we will briefly describe how PSII functions and identify those aspects that are essential in order to catalyze the oxidation of water into O(2), and review previous attempts to design simple photo-catalytic proteins and summarize our current research exploiting the E. coli bacterioferritin protein as a scaffold into which multiple cofactors can be bound, to oxidize a manganese metal center upon illumination. Through the reverse engineering of PSII and light driven water splitting reactions it may be possible to provide a blueprint for catalysts that can produce clean green fuel for human energy needs.
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Affiliation(s)
- Brendon Conlan
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia.
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Mino H, Kawamori A. The differences in microenvironments and functions of tyrosine radicals YZ and YD in photosystem II studied by EPR. PHOTOSYNTHESIS RESEARCH 2008; 98:151-157. [PMID: 18985433 DOI: 10.1007/s11120-008-9380-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Accepted: 10/09/2008] [Indexed: 05/27/2023]
Abstract
Electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) were performed to investigate the difference in microenvironments and functions between tyrosine Z (Y(Z)) and tyrosine D (Y(D)). Mn-depletion or Ca(2+)-depletion causes extension of the lifetime of tyrosine radical Y(Z)(*), which can be trapped by rapid freezing after illumination at about 250 K. Above pH 6.5, Y(Z)(*) radical in Mn-depleted PS II shows similar EPR and ENDOR spectra similar to that of Y(D)(*) radical, which are ascribed to a typical neutral tyrosine radical. Below pH 6.5, Y(Z)(*) radical shows quite different EPR and ENDOR spectra. ENDOR spectra show the spin density distribution of the low-pH form of Y(Z)(*) that has been quite different from the high-pH form of Y(Z)(*). The spin density distribution of the low-pH Y(Z)(*) can be explained by a cation radical or the neutral radical induced by strong electrostatic interaction. The pH dependence of the activation energy of the recombination rate between Y(Z)(*) and Q(A)(-) shows a gap of 4.4 kJ/mol at pH 6.0-6.5. In the Ca(2+)-depleted PS II, Y(Z)(*) signal was the mixture of the cation-like and normal neutral radicals, and the pH dependence of Y(Z)(*) spectrum in Ca(2+)-depleted PS II is considerably different from the neutral radical found in Mn-depleted PS II. Based on the recent structure data of cyanobacterial PS II, the pH dependence of Y(Z)(*) could be ascribed to the modification of the local structure and hydrogen-bonding network induced by the dissociation of ASP170 near Y(Z).
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Affiliation(s)
- Hiroyuki Mino
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan.
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Renger G, Renger T. Photosystem II: The machinery of photosynthetic water splitting. PHOTOSYNTHESIS RESEARCH 2008; 98:53-80. [PMID: 18830685 DOI: 10.1007/s11120-008-9345-7] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 07/29/2008] [Indexed: 05/26/2023]
Abstract
This review summarizes our current state of knowledge on the structural organization and functional pattern of photosynthetic water splitting in the multimeric Photosystem II (PS II) complex, which acts as a light-driven water: plastoquinone-oxidoreductase. The overall process comprises three types of reaction sequences: (1) photon absorption and excited singlet state trapping by charge separation leading to the ion radical pair [Formula: see text] formation, (2) oxidative water splitting into four protons and molecular dioxygen at the water oxidizing complex (WOC) with P680+* as driving force and tyrosine Y(Z) as intermediary redox carrier, and (3) reduction of plastoquinone to plastoquinol at the special Q(B) binding site with Q(A)-* acting as reductant. Based on recent progress in structure analysis and using new theoretical approaches the mechanism of reaction sequence (1) is discussed with special emphasis on the excited energy transfer pathways and the sequence of charge transfer steps: [Formula: see text] where (1)(RC-PC)* denotes the excited singlet state (1)P680* of the reaction centre pigment complex. The structure of the catalytic Mn(4)O(X)Ca cluster of the WOC and the four step reaction sequence leading to oxidative water splitting are described and problems arising for the electronic configuration, in particular for the nature of redox state S(3), are discussed. The unravelling of the mode of O-O bond formation is of key relevance for understanding the mechanism of the process. This problem is not yet solved. A multistate model is proposed for S(3) and the functional role of proton shifts and hydrogen bond network(s) is emphasized. Analogously, the structure of the Q(B) site for PQ reduction to PQH(2) and the energetic and kinetics of the two step redox reaction sequence are described. Furthermore, the relevance of the protein dynamics and the role of water molecules for its flexibility are briefly outlined. We end this review by presenting future perspectives on the water oxidation process.
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Affiliation(s)
- Gernot Renger
- Max Volmer Laboratory for Biophysical Chemistry, Berlin Institute of Technology, Berlin, Germany.
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