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Semin B, Loktyushkin A, Lovyagina E. Current analysis of cations substitution in the oxygen-evolving complex of photosystem II. Biophys Rev 2024; 16:237-247. [PMID: 38737202 PMCID: PMC11078907 DOI: 10.1007/s12551-024-01186-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 03/27/2024] [Indexed: 05/14/2024] Open
Abstract
Water oxidation in photosystem II (PSII) is performed by the oxygen-evolving complex Mn4CaO5 which can be extracted from PSII and then reconstructed using exogenous cations Mn(II) and Ca2+. The binding efficiency of other cations to the Mn-binding sites in Mn-depleted PSII was investigated without any positive results. At the same time, a study of the Fe cations interaction with Mn-binding sites showed that it binds at a level comparable with the binding of Mn cations. Binding of Fe(II) cations first requires its light-dependent oxidation. In general, the interaction of Fe(II) with Mn-depleted PSII has a number of features similar to the two-quantum model of photoactivation of the complex with the release of oxygen. Interestingly, incubation of Ca-depleted PSII with Fe(II) cations under certain conditions is accompanied by the formation of a chimeric cluster Mn/Fe in the oxygen-evolving complex. PSII with the cluster 2Mn2Fe was found to be capable of water oxidation, but only to the H2O2 intermediate. However, the cluster 3Mn1Fe can oxidize water to O2 with an efficiency about 25% of the original in the absence of extrinsic proteins PsbQ and PsbP. In the presence of these proteins, the efficiency of O2 evolution can reach 80% of the original when adding exogenous Ca2+. In this review, we summarized information on the formation of chimeric Mn-Fe clusters in the oxygen-evolving complex. The data cited may be useful for detailing the mechanism of water oxidation.
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Affiliation(s)
- Boris Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia 119234
| | - Aleksey Loktyushkin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia 119234
| | - Elena Lovyagina
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia 119234
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Lovyagina ER, Luneva OG, Loktyushkin AV, Semin BK. Effect of lanthanides on oxidation of Mn 2+ cations via a high-affinity Mn-binding site in photosystem II membranes. J Inorg Biochem 2023; 244:112237. [PMID: 37105009 DOI: 10.1016/j.jinorgbio.2023.112237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 04/04/2023] [Accepted: 04/19/2023] [Indexed: 04/29/2023]
Abstract
Lanthanide cations (La3+ and Tb3+) bind to the Ca-binding site of the oxygen-evolving complex in Ca-depleted PSII membranes and irreversibly inhibit the oxygen evolution. Оn the other hand, EPR measurement of Mn2+ concentration in buffer revealed that lanthanide cations inhibit the light-dependent oxidation of Mn2+ cations via the high-affinity Mn-binding site in Mn-depleted PSII membranes, which suggests that they bind to and inhibit the high-affinity Mn-binding site of the oxygen-evolving complex. The inhibition is irreversible, bound Ln3+ cation could not be washed out from the sample. Calcium ion inhibits oxidation of Mn2+ (5 μM) at very high concentration (tens mM) and the inhibition is reversible. In this work we measured the reduction rate of exogenic electron acceptor 2,6-dichlorophenolindophenol during the oxidation of Mn2+ cations in the Ca-depleted PSII and in the Ca-depleted PSII treated with lanthanides after extraction of Mn cluster from these preparations. We found that irreversible binding of the lanthanide cation to the Ca-binding site in the Ca-depleted PSII membranes leads to a partial inhibition of the high-affinity Mn-binding site.
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Affiliation(s)
- E R Lovyagina
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - O G Luneva
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - A V Loktyushkin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - B K Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow 119234, Russia.
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Semin BК, Davletshina LN. High-efficiency oxygen evolution by photosystem II oxygen-evolving complex containing 3Mn per reaction center. J Biol Inorg Chem 2023; 28:393-401. [PMID: 37043043 DOI: 10.1007/s00775-023-01987-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 12/27/2022] [Indexed: 04/13/2023]
Abstract
Ca-depleted photosystem II membranes obtained by treatment with acidic buffer do not contain Ca2+ in the Mn4CaO5 cluster but contain all extrinsic proteins protecting this cluster (PSII(-Ca/low pH)). However, unlike native photosystem II, Mn cluster in PSII(-Ca/low pH) samples is available for small-sized reductants. Using this property, we investigated the substitution possibility of Mn cation(s) with Fe cation(s) to obtain a chimeric cluster in PSII(-Ca/low pH) samples containing extrinsic proteins. We found that Fe(II) cation replaces Mn cation at pH 6.5, however, PSII(-Ca/low pH) membranes with the 3Mn1Fe chimeric cluster in the oxygen-evolving complex evolve O2 with high intensity in the presence of exogenous Ca2+. The O2 evolution rate is about 80% of the same rate in PSII(-Ca/low pH) membranes.
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Affiliation(s)
- Boris К Semin
- Department of Biophysics, Faculty of Biology, Moscow State University, Moscow, 119234, Russia.
| | - Lira N Davletshina
- Department of Biophysics, Faculty of Biology, Moscow State University, Moscow, 119234, Russia
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Semin BК, Davletshina LN, Goryachev SN, Seibert M. Ca 2+ effects on Fe(II) interactions with Mn-binding sites in Mn-depleted oxygen-evolving complexes of photosystem II and on Fe replacement of Mn in Mn-containing, Ca-depleted complexes. PHOTOSYNTHESIS RESEARCH 2021; 147:229-237. [PMID: 33532973 DOI: 10.1007/s11120-020-00813-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/11/2020] [Indexed: 06/12/2023]
Abstract
Fe(II) cations bind with high efficiency and specificity at the high-affinity (HA), Mn-binding site (termed the "blocking effect" since Fe blocks further electron donation to the site) of the oxygen-evolving complex (OEC) in Mn-depleted, photosystem II (PSII) membrane fragments (Semin et al. in Biochemistry 41:5854, 2002). Furthermore, Fe(II) cations can substitute for 1 or 2Mn cations (pH dependent) in Ca-depleted PSII membranes (Semin et al. in Journal of Bioenergetics and Biomembranes 48:227, 2016; Semin et al. in Journal of Photochemistry and Photobiology B 178:192, 2018). In the current study, we examined the effect of Ca2+ cations on the interaction of Fe(II) ions with Mn-depleted [PSII(-Mn)] and Ca-depleted [PSII(-Ca)] photosystem II membranes. We found that Ca2+ cations (about 50 mM) inhibit the light-dependent oxidation of Fe(II) (5 µM) by about 25% in PSII(-Mn) membranes, whereas inhibition of the blocking process is greater at about 40%. Blocking of the HA site by Fe cations also decreases the rate of charge recombination between QA- and YZ•+ from t1/2 = 30 ms to 46 ms. However, Ca2+ does not affect the rate during the blocking process. An Fe(II) cation (20 µM) replaces 1Mn cation in the Mn4CaO5 catalytic cluster of PSII(-Ca) membranes at pH 5.7 but 2 Mn cations at pH 6.5. In the presence of Ca2+ (10 mM) during the substitution process, Fe(II) is not able to extract Mn at pH 5.7 and extracts only 1Mn at pH 6.5 (instead of two without Ca2+). Measurements of fluorescence induction kinetics support these observations. Inhibition of Mn substitution with Fe(II) cations in the OEC only occurs with Ca2+ and Sr2+ cations, which are also able to restore oxygen evolution in PSII(-Ca) samples. Nonactive cations like La3+, Ni2+, Cd2+, and Mg2+ have no influence on the replacement of Mn with Fe. These results show that the location and/or ligand composition of one Mn cation in the Mn4CaO5 cluster is strongly affected by calcium depletion or rebinding and that bound calcium affects the redox potential of the extractable Mn4 cation in the OEC, making it resistant to reduction.
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Affiliation(s)
- B К Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia, 119234.
| | - L N Davletshina
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - S N Goryachev
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - M Seibert
- Laboratory, BioEnergy Sciences and Technology Directorate, National Renewable Energy, Golden, CO, 80401, USA
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Lovyagina ER, Semin BK. The Thermal Stability of Electron Transfer in Membrane Preparations of Photosystem II with a Ca
2+
-Depleted Oxygen-Evolving Complex. Biophysics (Nagoya-shi) 2021. [DOI: 10.1134/s0006350921010097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Effective binding of Tb 3+ and La 3+ cations on the donor side of Mn-depleted photosystem II. J Biol Inorg Chem 2020; 26:1-11. [PMID: 33146770 DOI: 10.1007/s00775-020-01832-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/20/2020] [Indexed: 10/23/2022]
Abstract
The interaction of Tb3+ and La3+ cations with different photosystem II (PSII) membranes (intact PSII, Ca-depleted PSII (PSII[-Ca]) and Mn-depleted PSII (PSII[-Mn]) membranes) was studied. Although both lanthanide cations (Ln3+) interact only with Ca2+-binding site of oxygen-evolving complex (OEC) in PSII and PSII(-Ca) membranes, we found that in PSII(-Mn) membranes both Ln3+ ions tightly bind to another site localized on the oxidizing side of PSII. Binding of Ln3+ cations to this site is not protected by Ca2+ and is accompanied by very effective inhibition of Mn2+ oxidation at the high-affinity (HA) Mn-binding site ([Mn2+ + H2O2] couple was used as a donor of electrons). The values of the constant for inhibition of electron transport Ki are equal to 2.10 ± 0.03 µM for Tb3+ and 8.3 ± 0.4 µM for La3+, whereas OEC inhibition constant in the native PSII membranes is 323 ± 7 µM for Tb3+. The value of Ki for Tb3+ corresponds to Ki for Mn2+ cations in the reaction of diphenylcarbazide oxidation via HA site (1.5 µM) presented in the literature. Our results suggest that Ln3+ cations bind to the HA Mn-binding site in PSII(-Mn) membranes like Mn2+ or Fe2+ cations. Taking into account the fact that Mn2+ and Fe2+ cations bind to the HA site as trivalent cations after light-induced oxidation and the fact that Mn cation bound to the HA site (Mn4) is also in trivalent state, we can suggest that valency may be important for the interaction of Ln3+ with the HA site.
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Davletshina LN, Semin BK. pH dependence of photosystem II photoinhibition: relationship with structural transition of oxygen-evolving complex at the pH of thylakoid lumen. PHOTOSYNTHESIS RESEARCH 2020; 145:135-143. [PMID: 32602041 DOI: 10.1007/s11120-020-00769-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
Ca-depleted photosystem II membranes (PSII[-Ca]) do not contain PsbP and PsbQ proteins protecting the Mn4CaO5 cluster of the PSII oxygen-evolving complex (OEC). Therefore, the Mn ions in the PSII(-Ca) membranes can be reduced by exogenous bulky reductants or the charged reductant Fe(II). We have recently found that the resistance of Mn ions in the OEC to the Fe(II) action is pH dependent and that this reductant is less effective at pH 5.7 than at pH 6.5 (Semin et al. J Photochem Photobiol B 178:192, 2018). Taking these data into account, we investigated the photoinhibition in different PSII membranes at pH 5.7 and 6.5 and found that the resistance to photoinhibition of PSII and PSII(-Ca) membranes with a Mn cluster is higher at pH 5.7 than at pH 6.5, whereas the resistance of the Mn-depleted PSII membranes is pH independent. In thylakoids, light generates the transmembrane ΔpH, leading to the acidulation of lumen that results in pH 5.7. The uncouplers (NH4Cl or nigericin) that significantly prevent acidulation increase the rate of PSII photoinhibition in thylakoids. We suggest that the structural transition in the OEC at pH 5.7 plays a role of a built-in mechanism increasing the resistance of OEC to photoinhibition under illumination, since it is accompanied by a pH decrease in lumen to 5.7. The coincidence of these pH values, i.e. lumen pH under illumination and pH of the maximal resistance of the Mn cluster to the reduction by reductants, can point at the pH-dependent mechanism of PSII self-protection from photoinactivation.
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Affiliation(s)
- L N Davletshina
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234, Moscow, Russia
| | - B K Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234, Moscow, Russia.
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Yamamoto K, Takatsuka K. On the photocatalytic cycle of water splitting with small manganese oxides and the roles of water clusters as direct sources of oxygen molecules. Phys Chem Chem Phys 2018; 20:6708-6725. [DOI: 10.1039/c7cp07171j] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A study on the photocatalytic cycle of water splitting and coupled proton electron-wavepacket transfer (CPEWT) as key processes of the mechanism.
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Affiliation(s)
- Kentaro Yamamoto
- Fukui Institute for Fundamental Chemistry
- Kyoto University
- Kyoto 606-8103
- Japan
| | - Kazuo Takatsuka
- Fukui Institute for Fundamental Chemistry
- Kyoto University
- Kyoto 606-8103
- Japan
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Semin BК, Davletshina LN, Seibert M, Rubin AB. Creation of a 3Mn/1Fe cluster in the oxygen-evolving complex of photosystem II and investigation of its functional activity. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2017; 178:192-200. [PMID: 29156347 DOI: 10.1016/j.jphotobiol.2017.11.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/28/2017] [Accepted: 11/09/2017] [Indexed: 01/04/2023]
Abstract
Extraction of Mn cations from the oxygen-evolving complex (OEC) of Ca-depleted PSII membranes (PSII[-Ca,4Mn]) by reductants like hydroquinone (H2Q) occurs with lower efficiency at acidic pH (2Mn/reaction center [RC] are extracted at pH5.7) than at neutral pH (3Mn/RC are extracted at pH6.5) [Semin et al. Photosynth. Res. 125 (2015) 95]. Fe(II) also extracts Mn cations from PSII(-Ca,4Mn), but only 2Mn/RC at pH6.5, forming a heteronuclear 2Mn/2Fe cluster [Semin and Seibert, J. Bioenerg. Biomembr. 48 (2016) 227]. Here we investigated the efficiency of Mn extraction by Fe(II) at acidic pH and found that Fe(II) cations can extract only 1Mn/RC from PSII(-Ca,4Mn) membranes at pH 5.7, forming a 3Mn/1Fe cluster. Also we found that the presence of Fe cations in a heteronuclear cluster (2Mn/2Fe) increases the resistance of the remaining Mn cations to H2Q action, since H2Q can extract Mn cations from homonuclear Mn clusters of PSII(-Ca,4Mn) and PSII(-Ca,2Mn) membranes but not from the heteronuclear cluster in PSII(-Ca,2Mn,2Fe) membranes. H2Q also cannot extract Mn from PSII membranes obtained by incubation of PSII(-Ca,4Mn) membranes with Fe(II) cations at pH5.7, which suggests the formation of a heteronuclear 3Mn/1Fe cluster in the OEC. Functional activity of PSII with a 3Mn/1Fe cluster was investigated. PSII preparations with a 3Mn/1Fe cluster in the OEC are able to photoreduce the exogenous electron acceptor 2,6-dichlorophenolindophenol, possibly due to incomplete oxidation of water molecules as is the case with PSII(-Ca,2Mn,2Fe) samples. However, in the contrast to PSII(-Ca,2Mn,2Fe) samples PSII(-Ca,3Mn,1Fe) membranes can evolve O2 at a low rate in the presence of exogenous Ca2+ (at about 27% of the rate of O2 evolution in native PSII membranes). The explanation for this phenomenon (either water splitting and production of molecular O2 by the 3Mn/1Fe cluster or apparent O2 evolution due to minor contamination of PSII(3Mn,1Fe) samples with PSII(-Ca,4Mn) membranes) is discussed.
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Affiliation(s)
- B К Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia.
| | - L N Davletshina
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - M Seibert
- BioEnergy Sciences & Technology Directorate, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - A B Rubin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
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Amino acid oxidation of the D1 and D2 proteins by oxygen radicals during photoinhibition of Photosystem II. Proc Natl Acad Sci U S A 2017; 114:2988-2993. [PMID: 28265052 DOI: 10.1073/pnas.1618922114] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Photosystem II reaction center is vulnerable to photoinhibition. The D1 and D2 proteins, lying at the core of the photosystem, are susceptible to oxidative modification by reactive oxygen species that are formed by the photosystem during illumination. Using spin probes and EPR spectroscopy, we have determined that both O2•- and HO• are involved in the photoinhibitory process. Using tandem mass spectroscopy, we have identified a number of oxidatively modified D1 and D2 residues. Our analysis indicates that these oxidative modifications are associated with formation of HO• at both the Mn4O5Ca cluster and the nonheme iron. Additionally, O2•- appears to be formed by the reduction of O2 at either PheoD1 or QA Early oxidation of D1:332H, which is coordinated with the Mn1 of the Mn4O5Ca cluster, appears to initiate a cascade of oxidative events that lead to the oxidative modification of numerous residues in the C termini of the D1 and D2 proteins on the donor side of the photosystem. Oxidation of D2:244Y, which is a bicarbonate ligand for the nonheme iron, induces the propagation of oxidative reactions in residues of the D-de loop of the D2 protein on the electron acceptor side of the photosystem. Finally, D1:130E and D2:246M are oxidatively modified by O2•- formed by the reduction of O2 either by PheoD1•- or QA•- The identification of specific amino acid residues oxidized by reactive oxygen species provides insights into the mechanism of damage to the D1 and D2 proteins under light stress.
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Lovyagina ER, Semin BK. Mechanism of inhibition and decoupling of oxygen evolution from electron transfer in photosystem II by fluoride, ammonia and acetate. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2016; 158:145-53. [PMID: 26971280 DOI: 10.1016/j.jphotobiol.2016.02.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 02/08/2016] [Accepted: 02/11/2016] [Indexed: 11/25/2022]
Abstract
Ca(2+) extraction from oxygen-evolving complex (OEC) of photosystem II (PSII) is accompanied by decoupling of oxygen evolution/electron transfer processes [Semin et al. Photosynth. Res. 98 (2008) 235] and appearance of a broad EPR signal at g=2 (split "S3" signal) what can imply the relationship between these effects. Split signal have been observed not only in Ca-depleted PSII but also in PSII membranes treated by fluoride anions, sodium acetate, and NH4Cl. Here we investigated the question: can such compounds induce the decoupling effect during treatment of PSII like Ca(2+) extraction does? We found that F(-), sodium acetate, and NH4Cl inhibit O2 evolution in PSII membranes more effectively than the reduction of artificial electron acceptor 2,6-dichlorophenolindophenol, i.e. the action of these compounds is accompanied by decoupling of these processes in OEC. Similarity of effects observed after Ca(2+) extraction and F(-), CH3COO(-) or NH4Cl treatments suggests that these compounds can inactivate function of Ca(2+). Such inactivation could originate from disturbance of the network of functionally active hydrogen bonds around OEC formed with participation of Ca(2+). This inhibition effect is observed in the region of low concentration of inhibitors. Increasing of inhibitor concentration is accompanied by appearance of other sites of inhibition.
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Affiliation(s)
- E R Lovyagina
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - B K Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia.
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Semin BK, Seibert M. Substituting Fe for two of the four Mn ions in photosystem II-effects on water-oxidation. J Bioenerg Biomembr 2016; 48:227-40. [PMID: 26847716 DOI: 10.1007/s10863-016-9651-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 01/28/2016] [Indexed: 10/22/2022]
Abstract
We have investigated the interaction of Fe(II) cations with Ca-depleted PSII membranes (PSII[-Ca,4Mn]) in the dark and found that Fe(II) incubation removes 2 of 4 Mn ions from the tetranuclear Mn cluster of the photosynthetic O2-evolving complex (OEC). The reduction of Mn ions in PSII(-Ca,4Mn) by Fe(II) and the concomitant release of two Mn(II) cations is accompanied by the binding of newly generated Fe(III) in at least one vacated Mn site. Flash-induced chlorophyll (Chl) fluorescence yield measurements of this new 2Mn/nFe cluster (PSII[-Ca,2Mn,nFe]) show that charge recombination in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) occurs between Qa (-) and the remaining Mn/Fe cluster (but not YZ (●)) in the OEC, and extraction of 2 Mn occurs uniformly in all PSII complexes. No O2 evolution is observed, but the heteronuclear metal cluster in PSII(-Ca,2Mn,nFe) samples is still able to supply electrons for reduction of the exogenous electron acceptor, 2,6-dichlorophrenolindophenol, by photooxidizing water and producing H2O2 in the absence of an exogenous donor as seen previously with PSII(-Ca,4Mn). Selective extraction of Mn or Fe cations from the 2Mn/nFe heteronuclear cluster demonstrates that the high-affinity Mn-binding site is occupied by one of the iron cations. It is notable that partial water-oxidation function still occurs when only two Mn cations are present in the PSII OEC.
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Affiliation(s)
- Boris K Semin
- BioEnergy Sciences & Technology Directorate, National Renewable Energy Laboratory, Golden, CO, 80401, USA. .,Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234, Moscow, Russia.
| | - Michael Seibert
- BioEnergy Sciences & Technology Directorate, National Renewable Energy Laboratory, Golden, CO, 80401, USA
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Walsh D, Sanchez-Ballester NM, Ting VP, Ariga K, Weller MT. Visible light promoted photocatalytic water oxidation: proton and electron collection via a reversible redox dye mediator. Catal Sci Technol 2016. [DOI: 10.1039/c6cy00139d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A quinone analogue as reversible electron and proton collector in visible light promoted water oxidations was investigated. Reagents were incorporated into microporous silica with surface absorbed cobalt catalyst. Reversible storage molecules are an important step towards solar fuels.
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Affiliation(s)
| | | | - Valeska P. Ting
- Department of Chemical Engineering
- University of Bath
- Bath BA2 7AY
- UK
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Mattila H, Khorobrykh S, Havurinne V, Tyystjärvi E. Reactive oxygen species: Reactions and detection from photosynthetic tissues. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 152:176-214. [PMID: 26498710 DOI: 10.1016/j.jphotobiol.2015.10.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/30/2015] [Accepted: 10/01/2015] [Indexed: 12/22/2022]
Abstract
Reactive oxygen species (ROS) have long been recognized as compounds with dual roles. They cause cellular damage by reacting with biomolecules but they also function as agents of cellular signaling. Several different oxygen-containing compounds are classified as ROS because they react, at least with certain partners, more rapidly than ground-state molecular oxygen or because they are known to have biological effects. The present review describes the typical reactions of the most important ROS. The reactions are the basis for both the detection methods and for prediction of reactions between ROS and biomolecules. Chemical and physical methods used for detection, visualization and quantification of ROS from plants, algae and cyanobacteria will be reviewed. The main focus will be on photosynthetic tissues, and limitations of the methods will be discussed.
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Affiliation(s)
- Heta Mattila
- Department of Biochemistry/Molecular Plant Biology, University of Turku, 20014 Turku, Finland
| | - Sergey Khorobrykh
- Department of Biochemistry/Molecular Plant Biology, University of Turku, 20014 Turku, Finland
| | - Vesa Havurinne
- Department of Biochemistry/Molecular Plant Biology, University of Turku, 20014 Turku, Finland
| | - Esa Tyystjärvi
- Department of Biochemistry/Molecular Plant Biology, University of Turku, 20014 Turku, Finland.
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Semin BK, Podkovirina TE, Davletshina LN, Timofeev KN, Ivanov II, Rubin AB. The extrinsic PsbO protein modulates the oxidation/reduction rate of the exogenous Mn cation at the high-affinity Mn-binding site of Mn-depleted PSII membranes. J Bioenerg Biomembr 2015; 47:361-7. [PMID: 26183834 DOI: 10.1007/s10863-015-9618-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/07/2015] [Indexed: 11/26/2022]
Abstract
The oxidation of exogenous Mn(II) cations at the high-affinity (HA) Mn-binding site in Mn-depleted photosystem II (PSII) membranes with or without the presence of the extrinsic PsbO polypeptide was studied by EPR. The six-lines EPR spectrum of Mn(II) cation disappears in the absence of the PsbO protein in membranes under illumination, but there was no effect when PSII preparations bound the PsbO protein. Our study demonstrates that such effect is determined by significant influence of the PsbO protein on the ratio between the rates of Mn oxidation and reduction at the HA site when the membranes are illuminated.
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Affiliation(s)
- Boris K Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234, Moscow, Russia,
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