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Shevela D, Schröder WP, Messinger J. Measurements of Oxygen Evolution in Photosynthesis. Methods Mol Biol 2024; 2790:133-148. [PMID: 38649570 DOI: 10.1007/978-1-0716-3790-6_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
This chapter compares two different techniques for monitoring photosynthetic O2 production; the wide-spread Clark-type O2 electrode and the more sophisticated membrane inlet mass spectrometry (MIMS) technique. We describe how a simple membrane inlet for MIMS can be made out of a commercial Clark-type cell and outline the advantages and drawbacks of the two techniques to guide researchers in deciding which method to use. Protocols and examples are given for measuring O2 evolution rates and for determining the number of chlorophyll molecules per active photosystem II reaction center.
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Affiliation(s)
| | | | - Johannes Messinger
- Department of Chemistry, Umeå University, Umeå, Sweden.
- Department of Chemistry - Ångström, Uppsala University, Uppsala, Sweden.
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2
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Kamada S, Nakajima Y, Shen JR. Structural insights into the action mechanisms of artificial electron acceptors in photosystem II. J Biol Chem 2023:104839. [PMID: 37209822 PMCID: PMC10300377 DOI: 10.1016/j.jbc.2023.104839] [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: 04/06/2023] [Revised: 05/07/2023] [Accepted: 05/15/2023] [Indexed: 05/22/2023] Open
Abstract
Photosystem II (PSII) utilizes light energy to split water, and the electrons extracted from water are transferred to QB, a plastoquinone (PQ) molecule bound to the D1 subunit of PSII. Many artificial electron acceptors (AEAs) with similar molecular structures to PQ can accept electrons from PSII. However, the molecular mechanism by which AEAs act on PSII is unclear. Here, we solved the crystal structure of PSII treated with three different AEAs, 2,5-dibromo-1,4-benzoquinone, 2,6-dichloro-1,4-benzoquinone, and 2-phenyl-1,4-benzoquinone, at 1.95-2.10 Å resolution. Our results show that all AEAs substitute for QB and are bound to the QB-binding site (QB site) to receive electrons, but their binding strengths are different, resulting in differences in their efficiencies to accept electrons. The acceptor 2-phenyl-1,4-benzoquinone binds most weakly to the QB site, and showed the highest oxygen-evolving activity, implying a reverse relationship between the binding strength and oxygen-evolving activity. In addition, a novel quinone binding site, designated the QD site, was discovered, which is located in the vicinity of QB site and close to QC site, a binding site reported previously. This QD site is expected to play a role as a channel or a storage site for quinones to be transported to the QB site. These results provide the structural basis for elucidating the actions of AEAs and exchange mechanism of QB in PSII, and also provide information for the design of more efficient electron acceptors.
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Affiliation(s)
- Shinji Kamada
- Faculty of Science, Okayama University, Okayama 700-8503, Japan
| | - Yoshiki Nakajima
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8503, Japan.
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8503, Japan.
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3
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Action of 2,6-Dichloro-1,4-benzoquinone on the O2-Evolving Activity of Photosystem II in Chlamydomonas reinhardtii Cells with and without Cell Wall: Inhibitory Effect of Its Oxidized Form. Cells 2023; 12:cells12060907. [PMID: 36980248 PMCID: PMC10046965 DOI: 10.3390/cells12060907] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/01/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
Chlamydomonas reinhardtii is a widely used object in studies on green algae concerning both photosynthesis aspects and possible biotechnological approaches. The measurement of the maximum O2 evolution by photosystem II (PSII) in living algal cells in the presence of artificial acceptors is one of the commonly used methods for determining the photosynthetic apparatus state or its change as compared to a control, parent strain, etc., because PSII is the most sensitive component of the thylakoid membrane. The present study shows the need to use low concentrations of 2,6-dichloro-1,4-benzoquinone (DCBQ) paired with potassium ferricyanide (FeCy) for achieving the maximum O2 evolution rate, while a DCBQ concentration above certain threshold results in strong suppression of O2 evolution. The required DCBQ concentration depends on the presence of the cell wall and should be exactly ~0.1 mM or in the range of 0.2–0.4 mM for cells with and without a cell wall, respectively. The inhibition effect is caused, probably, by a higher content of DCBQ in the oxidized form inside cells; this depends on the presence of the cell wall, which influences the efficiency of DCBQ diffusion into and out of the cell, where it is maintained by FeCy in the oxidized state. The possible mechanism of DCBQ inhibition action is discussed.
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4
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Lubitz W, Pantazis DA, Cox N. Water oxidation in oxygenic photosynthesis studied by magnetic resonance techniques. FEBS Lett 2023; 597:6-29. [PMID: 36409002 DOI: 10.1002/1873-3468.14543] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 11/23/2022]
Abstract
The understanding of light-induced biological water oxidation in oxygenic photosynthesis is of great importance both for biology and (bio)technological applications. The chemically difficult multistep reaction takes place at a unique protein-bound tetra-manganese/calcium cluster in photosystem II whose structure has been elucidated by X-ray crystallography (Umena et al. Nature 2011, 473, 55). The cluster moves through several intermediate states in the catalytic cycle. A detailed understanding of these intermediates requires information about the spatial and electronic structure of the Mn4 Ca complex; the latter is only available from spectroscopic techniques. Here, the important role of Electron Paramagnetic Resonance (EPR) and related double resonance techniques (ENDOR, EDNMR), complemented by quantum chemical calculations, is described. This has led to the elucidation of the cluster's redox and protonation states, the valence and spin states of the manganese ions and the interactions between them, and contributed substantially to the understanding of the role of the protein surrounding, as well as the binding and processing of the substrate water molecules, the O-O bond formation and dioxygen release. Based on these data, models for the water oxidation cycle are developed.
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Affiliation(s)
- Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim/Ruhr, Germany
| | | | - Nicholas Cox
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
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Łazicka M, Palińska-Saadi A, Piotrowska P, Paterczyk B, Mazur R, Maj-Żurawska M, Garstka M. The coupled photocycle of phenyl-p-benzoquinone and Light-Harvesting Complex II (LHCII) within the biohybrid system. Sci Rep 2022; 12:12771. [PMID: 35896789 PMCID: PMC9329374 DOI: 10.1038/s41598-022-16892-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/18/2022] [Indexed: 11/09/2022] Open
Abstract
The combination of trimeric form of the light-harvesting complex II (LHCII3), a porous graphite electrode (GE), and the application of phenyl-p-benzoquinone (PPBQ), the quinone derivative, allow the construction of a new type of biohybrid photoactive system. The Chl fluorescence decay and voltammetric analyzes revealed that PPBQ impacts LHCII3 proportionally to accessible quenching sites and that PPBQ forms redox complexes with Chl in both ground and excited states. As a result, photocurrent generation is directly dependent on PPBQ-induced quenching of Chl fluorescence. Since PPBQ also undergoes photoactivation, the action of GE-LHCII3-PPBQ depends on the mutual coupling of LHCII3 and PPBQ photocycles. The GE-LHCII3-PPBQ generates a photocurrent of up to 4.5 µA and exhibits considerable stability during operation. The three-dimensional arrangement of graphite scraps in GE builds an active electrode surface and stabilizes LHCII3 in its native form in low-density multilayers. The results indicate the future usability of such designed photoactive device.
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Affiliation(s)
- Magdalena Łazicka
- Department of Metabolic Regulation, Faculty of Biology, Institute of Biochemistry, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland
| | - Adriana Palińska-Saadi
- Laboratory of Basics of Analytical Chemistry, Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093, Warsaw, Poland.,Bioanalytical Laboratory, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089, Warsaw, Poland
| | - Paulina Piotrowska
- Department of Metabolic Regulation, Faculty of Biology, Institute of Biochemistry, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland
| | - Bohdan Paterczyk
- Laboratory of Electron and Confocal Microscopy, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland
| | - Radosław Mazur
- Department of Metabolic Regulation, Faculty of Biology, Institute of Biochemistry, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland
| | - Magdalena Maj-Żurawska
- Laboratory of Basics of Analytical Chemistry, Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093, Warsaw, Poland
| | - Maciej Garstka
- Department of Metabolic Regulation, Faculty of Biology, Institute of Biochemistry, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland.
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6
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Han G, Chernev P, Styring S, Messinger J, Mamedov F. Molecular basis for turnover inefficiencies (misses) during water oxidation in photosystem II. Chem Sci 2022; 13:8667-8678. [PMID: 35974765 PMCID: PMC9337725 DOI: 10.1039/d2sc00854h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 07/04/2022] [Indexed: 11/24/2022] Open
Abstract
Photosynthesis stores solar light as chemical energy and efficiency of this process is highly important. The electrons required for CO2 reduction are extracted from water in a reaction driven by light-induced charge separations in the Photosystem II reaction center and catalyzed by the CaMn4O5-cluster. This cyclic process involves five redox intermediates known as the S0–S4 states. In this study, we quantify the flash-induced turnover efficiency of each S state by electron paramagnetic resonance spectroscopy. Measurements were performed in photosystem II membrane preparations from spinach in the presence of an exogenous electron acceptor at selected temperatures between −10 °C and +20 °C and at flash frequencies of 1.25, 5 and 10 Hz. The results show that at optimal conditions the turnover efficiencies are limited by reactions occurring in the water oxidizing complex, allowing the extraction of their S state dependence and correlating low efficiencies to structural changes and chemical events during the reaction cycle. At temperatures 10 °C and below, the highest efficiency (i.e. lowest miss parameter) was found for the S1 → S2 transition, while the S2 → S3 transition was least efficient (highest miss parameter) over the whole temperature range. These electron paramagnetic resonance results were confirmed by measurements of flash-induced oxygen release patterns in thylakoid membranes and are explained on the basis of S state dependent structural changes at the CaMn4O5-cluster that were determined recently by femtosecond X-ray crystallography. Thereby, possible “molecular errors” connected to the e− transfer, H+ transfer, H2O binding and O2 release are identified. Temperature dependence of the transition inefficiencies (misses) for the water oxidation process in photosystem II were studied by EPR spectroscopy and are explained on the basis of S state dependent structural changes at the CaMn4O5-cluster.![]()
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Affiliation(s)
- Guangye Han
- Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Petko Chernev
- Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Stenbjörn Styring
- Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Johannes Messinger
- Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Fikret Mamedov
- Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
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Vitukhnovskaya LA, Simonyan RA, Semenov AY, Mamedov MD. Generation of Photoelectric Responses by Photosystem II Core Complexes in the Presence of Externally Added Cytochrome c. BIOCHEMISTRY. BIOKHIMIIA 2021; 86:1369-1376. [PMID: 34906039 DOI: 10.1134/s0006297921110018] [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: 08/10/2021] [Revised: 09/20/2021] [Accepted: 09/20/2021] [Indexed: 06/14/2023]
Abstract
The effect of exogenous cytochrome c (cyt c) on kinetics of photoelectric responses (Δψ) of two types of photosystem II (PSII) core complexes (intact - PSII with active water-oxidizing complex and Mn-depleted complex) reconstituted into liposomes has been investigated by direct electrometric technique. PSII complexes were localized in the proteoliposome membranes with their donor side outward. An additional electrogenic phase was observed in the kinetics of Δψ generation in response to a laser flash besides the main fast (<0.3 µs) electrogenic component due to electron transfer from the redox-active tyrosine YZ to the primary quinone acceptor QA in the presence of oxidized cyt c (cyt c3+) entrapped in the internal space of proteoliposomes with intact PSII complexes. This component with characteristic time τ ≈ 40 µs and relative amplitude of ~10% of the total Δψ was attributed to the vectorial electron transfer from QA- to cyt c3+ serving as an external acceptor. An additional electrogenic component with τ ~ 70 µs and a relative amplitude of ~20% of the total Δψ also appeared in the kinetics of Δψ formation, when cyt c2+ was added to the suspension of proteoliposomes containing Mn-depleted PSII core complexes. This component was attributed to the electrogenic transfer of an electron from cyt c2+ to photooxidized tyrosine YZ. These data imply that cyt c3+ serves as a very effective exogenous electron acceptor for QA- in the case of intact PSII core complexes, and cyt c2+ is an extremely efficient artificial electron donor for YZ in the Mn-depleted PSII. The obtained data on the roles of cyt c2+ and cyt c3+ as an electron donor and acceptor for PSII, respectively, can be used to develop hybrid photoelectrochemical solar energy-converting systems based on photosynthetic pigment-protein complexes.
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Affiliation(s)
- Liya A Vitukhnovskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Ruben A Simonyan
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Alexey Yu Semenov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Mahir D Mamedov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
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8
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Trubitsin BV, Milanovsky GE, Mamedov MD, Semenov AY, Tikhonov AN. The Interaction of Water-Soluble Nitroxide Radicals with Photosystem II. APPLIED MAGNETIC RESONANCE 2021; 53:1053-1067. [PMID: 34522067 PMCID: PMC8428495 DOI: 10.1007/s00723-021-01425-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/03/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
In this work, we investigated the redox transients of a number of water-soluble spin labels upon their interactions with Photosystem II (PS II) core complexes isolated from spinach leaves. We have found that the reactivity of nitroxide radicals, determined by the rate of their reduction upon illumination of PS II, depends on the chemical structure of radicals and the capability of their coming close to low-potential redox centers of photoactive PS II complexes. An enhanced capability of nitroxide radicals to accept electrons from PS II correlates with their chemical structure. Nitroxide radicals NTI (2,2,5,5-tetramethyl-4-nitromethylene-3-imidazolidine-N-oxyl) and Tacet (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl-acetate), containing polar groups, appear to be most efficient acceptors of electrons donated by PS II compared to neutral (TEMPOL, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) or positively charged (Tamine, 4-amino-2,2,6,6-tetramethylpiperidine-l-oxyl) spin labels. We assume that enhanced reactivities of polar nitroxide radicals, NTI and Tacet, are determined (1) by their relatively high redox potentials, providing the possibility to accept electrons from PS II, and (2) by their affinities to the closest binding sites on the surface of PS II in the vicinity of the primary plastoquinone acceptor PQA (12-14 Å) or/and in the intraprotein cavity for the secondary plastoquinone PQB (~ 22 Å).
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Affiliation(s)
- B. V. Trubitsin
- Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - G. E. Milanovsky
- Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - M. D. Mamedov
- Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - A. Yu. Semenov
- Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - A. N. Tikhonov
- Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia
- N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, Moscow, Russia
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9
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Mamedov MD, Milanovsky GE, Malferrari M, Vitukhnovskaya LA, Francia F, Semenov AY, Venturoli G. Trehalose matrix effects on electron transfer in Mn-depleted protein-pigment complexes of Photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148413. [PMID: 33716033 DOI: 10.1016/j.bbabio.2021.148413] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/15/2021] [Accepted: 03/07/2021] [Indexed: 11/18/2022]
Abstract
The kinetics of flash-induced re-reduction of the Photosystem II (PS II) primary electron donor P680 was studied in solution and in trehalose glassy matrices at different relative humidity. In solution, and in the re-dissolved glass, kinetics were dominated by two fast components with lifetimes in the range of 2-7 μs, which accounted for >85% of the decay. These components were ascribed to the direct electron transfer from the redox-active tyrosine YZ to P680+. The minor slower components were due to charge recombination between the primary plastoquinone acceptor QA- and P680+. Incorporation of the PS II complex into the trehalose glassy matrix and its successive dehydration caused a progressive increase in the lifetime of all kinetic phases, accompanied by an increase of the amplitudes of the slower phases at the expense of the faster phases. At 63% relative humidity the fast components contribution dropped to ~50%. A further dehydration of the trehalose glass did not change the lifetimes and contribution of the kinetic components. This effect was ascribed to the decrease of conformational mobility of the protein domain between YZ and P680, which resulted in the inhibition of YZ → P680+ electron transfer in about half of the PS II population, wherein the recombination between QA- and P680+ occurred. The data indicate that PS II binds a larger number of water molecules as compared to PS I complexes. We conclude that our data disprove the "water replacement" hypothesis of trehalose matrix biopreservation.
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Affiliation(s)
- Mahir D Mamedov
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Leninskye gory, 1, b.40, Russia
| | - Georgy E Milanovsky
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Leninskye gory, 1, b.40, Russia
| | - Marco Malferrari
- Laboratory of Biochemistry and Molecular Biophysics, Department of Pharmacy and Biotechnology, FaBiT, University of Bologna, Bologna, Via Irnerio, 42, Italy
| | - Liya A Vitukhnovskaya
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Leninskye gory, 1, b.40, Russia; N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Kosygina Street, 4, b.1, Russia
| | - Francesco Francia
- Laboratory of Biochemistry and Molecular Biophysics, Department of Pharmacy and Biotechnology, FaBiT, University of Bologna, Bologna, Via Irnerio, 42, Italy
| | - Alexey Yu Semenov
- A.N. Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Leninskye gory, 1, b.40, Russia; N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, 119991, Kosygina Street, 4, b.1, Russia.
| | - Giovanni Venturoli
- Laboratory of Biochemistry and Molecular Biophysics, Department of Pharmacy and Biotechnology, FaBiT, University of Bologna, Bologna, Via Irnerio, 42, Italy; Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, CNISM, c/o Department of Physics and Astronomy "Augusto Righi", DIFA, University of Bologna, Bologna, Via Irnerio, 46, Italy.
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10
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Zaspa AA, Vitukhnovskaya LA, Mamedova AM, Semenov AY, Mamedov MD. Photovoltage generation by photosystem II core complexes immobilized onto a Millipore filter on an indium tin oxide electrode. J Bioenerg Biomembr 2020; 52:495-504. [PMID: 33190172 DOI: 10.1007/s10863-020-09857-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/28/2020] [Indexed: 10/23/2022]
Abstract
The light-induced functioning of photosynthetic pigment-protein complex of photosystem II (PSII) is linked to the vectorial translocation of charges across the membrane, which results in the formation of voltage. Direct measurement of the light-induced voltage (∆V) generated by spinach oxygen-evolving PSII core complexes adsorbed onto a Millipore membrane filter (MF) on an indium tin oxide (ITO) electrode under continuous illumination has been performed. PSII was shown to participate in electron transfer from water to the ITO electrode, resulting in ∆V generation. No photovoltage was detected in PSII deprived of the water-oxidizing complex. The maximal and stable photoelectric signal was observed in the presence of disaccharide trehalose and 2,6-dichloro-1,4-benzoquinone, acting as a redox mediator between the primary quinone acceptor QA of PSII and electrode surface. Long time preservation of the steady-state photoactivity at room temperature in a simple in design ITO|PSII-MF|ITO system may be related to the retention of water molecules attached to the PSII surface in the presence of trehalose.
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Affiliation(s)
- Andrey A Zaspa
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Liya A Vitukhnovskaya
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.,N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Aida M Mamedova
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.,First Moscow State Medical University, Moscow, Russia
| | - Alexey Yu Semenov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.,N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia
| | - Mahir D Mamedov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
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11
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Lloret-Fillol J, Costas M. Water oxidation at base metal molecular catalysts. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2019. [DOI: 10.1016/bs.adomc.2019.02.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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12
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Das S, Maiti SK. PSII as an in vivo molecular catalyst for the production of energy rich hydroquinones - A new approach in renewable energy. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2018; 180:134-139. [PMID: 29413696 DOI: 10.1016/j.jphotobiol.2018.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/30/2018] [Accepted: 02/01/2018] [Indexed: 11/30/2022]
Abstract
One of the pertinent issues in the field of energy science today is the quest for an abundant source of hydrogen or hydrogen equivalents. In this study, phenyl-p-benzoquinone (pPBQ) has been used to generate a molecular store of hydrogen equivalents (phenyl-p-hydroquinone; pPBQH2) from thein vivo splitting of water by photosystem II of the marine cyanobacterium Synechococcus elongatus BDU 70542. Using this technique, 10.8 μmol of pPBQH2 per mg chlorophyll a can be extracted per minute, an efficiency that is orders of magnitude higher when compared to the techniques present in the current literature. Moreover, the photo-reduction process was stable when tested over longer periods of time. Addition of phenyl-p-benzoquinone on an intermittent basis resulted in the precipitation of phenyl-p-hydroquinone, obviating the need for costly downstream processing units for product recovery. Phenyl-p-hydroquinone so obtained is a molecular store of free energy preserved through the light driven photolysis of water and can be used as a cheap and a renewable source of hydrogen equivalents by employing transition metal catalysts or fuel cells with the concomitant regeneration of phenyl-p-benzoquinone. The cyclic nature of this technique makes it an ideal candidate to be utilized in mankind's transition from fossil fuels to solar fuels.
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Affiliation(s)
- Sai Das
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, India
| | - Soumen K Maiti
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, India.
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13
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Abstract
This chapter compares two different techniques for monitoring photosynthetic O2 production: the widespread Clark-type O2 electrode and the more sophisticated membrane inlet mass spectrometry (MIMS) technique. We describe how a simple membrane inlet for MIMS can be made out of a commercial Clark-type cell, and outline the advantages and drawbacks of the two techniques to guide researchers in deciding which method to use. Protocols and examples are given for measuring O2 evolution rates and for determining the number of chlorophyll molecules per active photosystem II reaction center.
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Affiliation(s)
| | | | - Johannes Messinger
- Department of Chemistry, Umeå University, Umeå, Sweden.
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, Sweden.
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14
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Photosystem II-cyclic electron flow powers exceptional photoprotection and record growth in the microalga Chlorella ohadii. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:873-883. [PMID: 28734933 DOI: 10.1016/j.bbabio.2017.07.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/12/2017] [Accepted: 07/14/2017] [Indexed: 01/13/2023]
Abstract
The desert microalga Chlorella ohadii was reported to grow at extreme light intensities with minimal photoinhibition, tolerate frequent de/re-hydrations, yet minimally employs antenna-based non-photochemical quenching for photoprotection. Here we investigate the molecular mechanisms by measuring Photosystem II charge separation yield (chlorophyll variable fluorescence, Fv/Fm) and flash-induced O2 yield to measure the contributions from both linear (PSII-LEF) and cyclic (PSII-CEF) electron flow within PSII. Cells grow increasingly faster at higher light intensities (μE/m2/s) from low (20) to high (200) to extreme (2000) by escalating photoprotection via shifting from PSII-LEF to PSII-CEF. This shifts PSII charge separation from plastoquinone reduction (PSII-LEF) to plastoquinol oxidation (PSII-CEF), here postulated to enable proton gradient and ATP generation that powers photoprotection. Low light-grown cells have unusually small antennae (332 Chl/PSII), use mainly PSII-LEF (95%) and convert 40% of PSII charge separations into O2 (a high O2 quantum yield of 0.06mol/mol PSII/flash). High light-grown cells have smaller antenna and lower PSII-LEF (63%). Extreme light-grown cells have only 42 Chl/PSII (no LHCII antenna), minimal PSII-LEF (10%), and grow faster than any known phototroph (doubling time 1.3h). Adding a synthetic quinone in excess to supplement the PQ pool fully uncouples PSII-CEF from its natural regulation and produces maximum PSII-LEF. Upon dark adaptation PSII-LEF rapidly reverts to PSII-CEF, a transient protection mechanism to conserve water and minimize the cost of antenna biosynthesis. The capacity of the electron acceptor pool (plastoquinone pool), and the characteristic times for exchange of (PQH2)B with PQpool and reoxidation of (PQH2)pool were determined.
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15
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Brinkert K, Le Formal F, Li X, Durrant J, Rutherford AW, Fantuzzi A. Photocurrents from photosystem II in a metal oxide hybrid system: Electron transfer pathways. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1857:1497-1505. [PMID: 26946088 PMCID: PMC4990130 DOI: 10.1016/j.bbabio.2016.03.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/19/2016] [Accepted: 03/01/2016] [Indexed: 12/21/2022]
Abstract
We have investigated the nature of the photocurrent generated by Photosystem II (PSII), the water oxidizing enzyme, isolated from Thermosynechococcus elongatus, when immobilized on nanostructured titanium dioxide on an indium tin oxide electrode (TiO2/ITO). We investigated the properties of the photocurrent from PSII when immobilized as a monolayer versus multilayers, in the presence and absence of an inhibitor that binds to the site of the exchangeable quinone (QB) and in the presence and absence of exogenous mobile electron carriers (mediators). The findings indicate that electron transfer occurs from the first quinone (QA) directly to the electrode surface but that the electron transfer through the nanostructured metal oxide is the rate-limiting step. Redox mediators enhance the photocurrent by taking electrons from the nanostructured semiconductor surface to the ITO electrode surface not from PSII. This is demonstrated by photocurrent enhancement using a mediator incapable of accepting electrons from PSII. This model for electron transfer also explains anomalies reported in the literature using similar and related systems. The slow rate of the electron transfer step in the TiO2 is due to the energy level of electron injection into the semiconducting material being below the conduction band. This limits the usefulness of the present hybrid electrode. Strategies to overcome this kinetic limitation are discussed.
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Affiliation(s)
- Katharina Brinkert
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Florian Le Formal
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Xiaoe Li
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - James Durrant
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | | | - Andrea Fantuzzi
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
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16
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Shevela D, Arnold J, Reisinger V, Berends HM, Kmiec K, Koroidov S, Bue AK, Messinger J, Eichacker LA. Biogenesis of water splitting by photosystem II during de-etiolation of barley (Hordeum vulgare L.). PLANT, CELL & ENVIRONMENT 2016; 39:1524-1536. [PMID: 26836813 DOI: 10.1111/pce.12719] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/14/2016] [Accepted: 01/17/2016] [Indexed: 06/05/2023]
Abstract
Etioplasts lack thylakoid membranes and photosystem complexes. Light triggers differentiation of etioplasts into mature chloroplasts, and photosystem complexes assemble in parallel with thylakoid membrane development. Plastids isolated at various time points of de-etiolation are ideal to study the kinetic biogenesis of photosystem complexes during chloroplast development. Here, we investigated the chronology of photosystem II (PSII) biogenesis by monitoring assembly status of chlorophyll-binding protein complexes and development of water splitting via O2 production in plastids (etiochloroplasts) isolated during de-etiolation of barley (Hordeum vulgare L.). Assembly of PSII monomers, dimers and complexes binding outer light-harvesting antenna [PSII-light-harvesting complex II (LHCII) supercomplexes] was identified after 1, 2 and 4 h of de-etiolation, respectively. Water splitting was detected in parallel with assembly of PSII monomers, and its development correlated with an increase of bound Mn in the samples. After 4 h of de-etiolation, etiochloroplasts revealed the same water-splitting efficiency as mature chloroplasts. We conclude that the capability of PSII to split water during de-etiolation precedes assembly of the PSII-LHCII supercomplexes. Taken together, data show a rapid establishment of water-splitting activity during etioplast-to-chloroplast transition and emphasize that assembly of the functional water-splitting site of PSII is not the rate-limiting step in the formation of photoactive thylakoid membranes.
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Affiliation(s)
- Dmitriy Shevela
- Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway
- Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden
| | - Janine Arnold
- Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway
| | - Veronika Reisinger
- Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway
| | - Hans-Martin Berends
- Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden
| | - Karol Kmiec
- Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway
| | - Sergey Koroidov
- Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden
- PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Ann Kristin Bue
- Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway
| | - Johannes Messinger
- Department of Chemistry, Chemical Biological Centre, Umeå University, S-90187, Umeå, Sweden
| | - Lutz A Eichacker
- Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036, Stavanger, Norway
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17
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Ananyev G, Gates C, Dismukes GC. The Oxygen quantum yield in diverse algae and cyanobacteria is controlled by partitioning of flux between linear and cyclic electron flow within photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1380-1391. [PMID: 27117512 DOI: 10.1016/j.bbabio.2016.04.056] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 04/20/2016] [Accepted: 04/21/2016] [Indexed: 01/07/2023]
Abstract
We have measured flash-induced oxygen quantum yields (O2-QYs) and primary charge separation (Chl variable fluorescence yield, Fv/Fm) in vivo among phylogenetically diverse microalgae and cyanobacteria. Higher O2-QYs can be attained in cells by releasing constraints on charge transfer at the Photosystem II (PSII) acceptor side by adding membrane-permeable benzoquinone (BQ) derivatives that oxidize plastosemiquinone QB(-) and QBH2. This method allows uncoupling PSII turnover from its natural regulation in living cells, without artifacts of isolating PSII complexes. This approach reveals different extents of regulation across species, controlled at the QB(-) acceptor site. Arthrospira maxima is confirmed as the most efficient PSII-WOC (water oxidizing complex) and exhibits the least regulation of flux. Thermosynechococcus elongatus exhibits an O2-QY of 30%, suggesting strong downregulation. WOC cycle simulations with the most accurate model (VZAD) show that a light-driven backward transition (net addition of an electron to the WOC, distinct from recombination) occurs in up to 25% of native PSIIs in the S2 and S3 states, while adding BQ prevents backward transitions and increases the lifetime of S2 and S3 by 10-fold. Backward transitions occur in PSIIs that have plastosemiquinone radicals in the QB site and are postulated to be physiologically regulated pathways for storing light energy as proton gradient through direct PSII-cyclic electron flow (PSII-CEF). PSII-CEF is independent of classical PSI/cyt-b6f-CEF and provides an alternative proton translocation pathway for energy conversion. PSII-CEF enables variable fluxes between linear and cyclic electron pathways, thus accommodating species-dependent needs for redox and ion-gradient energy sources powered by a single photosystem.
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Affiliation(s)
- Gennady Ananyev
- The Waksman Institute of Microbiology and the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, United States
| | - Colin Gates
- The Waksman Institute of Microbiology and the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, United States
| | - G Charles Dismukes
- The Waksman Institute of Microbiology and the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, United States.
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18
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Longatte G, Rappaport F, Wollman FA, Guille-Collignon M, Lemaître F. Mechanism and analyses for extracting photosynthetic electrons using exogenous quinones – what makes a good extraction pathway? Photochem Photobiol Sci 2016; 15:969-79. [DOI: 10.1039/c6pp00076b] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The extraction of photosynthetic electrons by exogenous quinones on unicellular green algae was investigated with fluorescence measurements. Zone diagrams were built for defining the most appropriate harvesting conditions.
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Affiliation(s)
- G. Longatte
- Ecole normale supérieure
- PSL Research University
- UPMC Univ Paris 06
- CNRS
- Département de Chimie
| | - F. Rappaport
- Laboratoire de physiologie membranaire et moléculaire du chloroplaste
- CNRS
- UPMC UMR 7141
- I.B.PC
- 75005 Paris
| | - F.-A. Wollman
- Laboratoire de physiologie membranaire et moléculaire du chloroplaste
- CNRS
- UPMC UMR 7141
- I.B.PC
- 75005 Paris
| | - M. Guille-Collignon
- Ecole normale supérieure
- PSL Research University
- UPMC Univ Paris 06
- CNRS
- Département de Chimie
| | - F. Lemaître
- Ecole normale supérieure
- PSL Research University
- UPMC Univ Paris 06
- CNRS
- Département de Chimie
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19
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Kern J, Tran R, Alonso-Mori R, Koroidov S, Echols N, Hattne J, Ibrahim M, Gul S, Laksmono H, Sierra RG, Gildea RJ, Han G, Hellmich J, Lassalle-Kaiser B, Chatterjee R, Brewster AS, Stan CA, Glöckner C, Lampe A, DiFiore D, Milathianaki D, Fry AR, Seibert MM, Koglin JE, Gallo E, Uhlig J, Sokaras D, Weng TC, Zwart PH, Skinner DE, Bogan MJ, Messerschmidt M, Glatzel P, Williams GJ, Boutet S, Adams PD, Zouni A, Messinger J, Sauter NK, Bergmann U, Yano J, Yachandra VK. Taking snapshots of photosynthetic water oxidation using femtosecond X-ray diffraction and spectroscopy. Nat Commun 2014; 5:4371. [PMID: 25006873 PMCID: PMC4151126 DOI: 10.1038/ncomms5371] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 06/10/2014] [Indexed: 01/07/2023] Open
Abstract
The dioxygen we breathe is formed by light-induced oxidation of water in photosystem II. O2 formation takes place at a catalytic manganese cluster within milliseconds after the photosystem II reaction centre is excited by three single-turnover flashes. Here we present combined X-ray emission spectra and diffraction data of 2-flash (2F) and 3-flash (3F) photosystem II samples, and of a transient 3F' state (250 μs after the third flash), collected under functional conditions using an X-ray free electron laser. The spectra show that the initial O-O bond formation, coupled to Mn reduction, does not yet occur within 250 μs after the third flash. Diffraction data of all states studied exhibit an anomalous scattering signal from Mn but show no significant structural changes at the present resolution of 4.5 Å. This study represents the initial frames in a molecular movie of the structural changes during the catalytic reaction in photosystem II.
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Affiliation(s)
- Jan Kern
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA,LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Rosalie Tran
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Sergey Koroidov
- Institutionen för Kemi, Kemiskt Biologiskt Centrum, Umeå Universitet, Umeå, Sweden
| | - Nathaniel Echols
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Johan Hattne
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Mohamed Ibrahim
- Institut für Biologie, Humboldt-Universität zu Berlin, D-10099 Berlin, Germany,Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität, D-10623 Berlin, Germany
| | - Sheraz Gul
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Hartawan Laksmono
- PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Raymond G. Sierra
- PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Richard J. Gildea
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Guangye Han
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Julia Hellmich
- Institut für Biologie, Humboldt-Universität zu Berlin, D-10099 Berlin, Germany,Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität, D-10623 Berlin, Germany
| | | | - Ruchira Chatterjee
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Aaron S. Brewster
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Claudiu A. Stan
- PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Carina Glöckner
- Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität, D-10623 Berlin, Germany
| | - Alyssa Lampe
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Dörte DiFiore
- Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität, D-10623 Berlin, Germany
| | | | - Alan R. Fry
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - M. Marvin Seibert
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Jason E. Koglin
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Erik Gallo
- European Synchrotron Radiation Facility, F-38043 Grenoble Cedex, France
| | - Jens Uhlig
- European Synchrotron Radiation Facility, F-38043 Grenoble Cedex, France
| | | | - Tsu-Chien Weng
- SSRL, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Petrus H. Zwart
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - David E. Skinner
- National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Michael J. Bogan
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA,PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | | | - Pieter Glatzel
- European Synchrotron Radiation Facility, F-38043 Grenoble Cedex, France
| | - Garth J. Williams
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Sébastien Boutet
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Paul D. Adams
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Athina Zouni
- Institut für Biologie, Humboldt-Universität zu Berlin, D-10099 Berlin, Germany,Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität, D-10623 Berlin, Germany
| | - Johannes Messinger
- Institutionen för Kemi, Kemiskt Biologiskt Centrum, Umeå Universitet, Umeå, Sweden
| | - Nicholas K. Sauter
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Uwe Bergmann
- LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA,Corresponding authors. (U.B.), , (J.Y.), (V.K.Y)
| | - Junko Yano
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA,Corresponding authors. (U.B.), , (J.Y.), (V.K.Y)
| | - Vittal K. Yachandra
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA,Corresponding authors. (U.B.), , (J.Y.), (V.K.Y)
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20
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Schuurmans RM, Schuurmans JM, Bekker M, Kromkamp JC, Matthijs HC, Hellingwerf KJ. The redox potential of the plastoquinone pool of the cyanobacterium Synechocystis species strain PCC 6803 is under strict homeostatic control. PLANT PHYSIOLOGY 2014; 165:463-75. [PMID: 24696521 PMCID: PMC4012603 DOI: 10.1104/pp.114.237313] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A method is presented for rapid extraction of the total plastoquinone (PQ) pool from Synechocystis sp. strain PCC 6803 cells that preserves the in vivo plastoquinol (PQH2) to -PQ ratio. Cells were rapidly transferred into ice-cold organic solvent for instantaneous extraction of the cellular PQ plus PQH2 content. After high-performance liquid chromatography fractionation of the organic phase extract, the PQH2 content was quantitatively determined via its fluorescence emission at 330 nm. The in-cell PQH2-PQ ratio then followed from comparison of the PQH2 signal in samples as collected and in an identical sample after complete reduction with sodium borohydride. Prior to PQH2 extraction, cells from steady-state chemostat cultures were exposed to a wide range of physiological conditions, including high/low availability of inorganic carbon, and various actinic illumination conditions. Well-characterized electron-transfer inhibitors were used to generate a reduced or an oxidized PQ pool for reference. The in vivo redox state of the PQ pool was correlated with the results of pulse-amplitude modulation-based chlorophyll a fluorescence emission measurements, oxygen exchange rates, and 77 K fluorescence emission spectra. Our results show that the redox state of the PQ pool of Synechocystis sp. strain PCC 6803 is subject to strict homeostatic control (i.e. regulated between narrow limits), in contrast to the more dynamic chlorophyll a fluorescence signal.
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21
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Shevela D, Nöring B, Koroidov S, Shutova T, Samuelsson G, Messinger J. Efficiency of photosynthetic water oxidation at ambient and depleted levels of inorganic carbon. PHOTOSYNTHESIS RESEARCH 2013; 117:401-12. [PMID: 23828399 DOI: 10.1007/s11120-013-9875-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Accepted: 06/20/2013] [Indexed: 05/09/2023]
Abstract
Over 40 years ago, Joliot et al. (Photochem Photobiol 10:309-329, 1969) designed and employed an elegant and highly sensitive electrochemical technique capable of measuring O2 evolved by photosystem II (PSII) in response to trains of single turn-over light flashes. The measurement and analysis of flash-induced oxygen evolution patterns (FIOPs) has since proven to be a powerful method for probing the turnover efficiency of PSII. Stemler et al. (Proc Natl Acad Sci USA 71(12):4679-4683, 1974), in Govindjee's lab, were the first to study the effect of "bicarbonate" on FIOPs by adding the competitive inhibitor acetate. Here, we extend this earlier work by performing FIOPs experiments at various, strictly controlled inorganic carbon (Ci) levels without addition of any inhibitors. For this, we placed a Joliot-type bare platinum electrode inside a N2-filled glove-box (containing 10-20 ppm CO2) and reduced the Ci concentration simply by washing the samples in Ci-depleted media. FIOPs of spinach thylakoids were recorded either at 20-times reduced levels of Ci or at ambient Ci conditions (390 ppm CO2). Numerical analysis of the FIOPs within an extended Kok model reveals that under Ci-depleted conditions the miss probability is discernibly larger (by 2-3 %) than at ambient conditions, and that the addition of 5 mM HCO3 (-) to the Ci-depleted thylakoids largely restores the original miss parameter. Since a "mild" Ci-depletion procedure was employed, we discuss our data with respect to a possible function of free or weakly bound HCO3 (-) at the water-splitting side of PSII.
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Affiliation(s)
- Dmitriy Shevela
- Department of Chemistry, Chemical Biological Centre, University of Umeå, 90187, Umeå, Sweden,
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22
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McKelvey K, Nadappuram BP, Actis P, Takahashi Y, Korchev YE, Matsue T, Robinson C, Unwin PR. Fabrication, characterization, and functionalization of dual carbon electrodes as probes for scanning electrochemical microscopy (SECM). Anal Chem 2013; 85:7519-26. [PMID: 23795948 PMCID: PMC3971958 DOI: 10.1021/ac401476z] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Dual carbon electrodes (DCEs) are quickly, easily, and cheaply fabricated by depositing pyrolytic carbon into a quartz theta nanopipet. The size of DCEs can be controlled by adjusting the pulling parameters used to make the nanopipet. When operated in generation/collection (G/C) mode, the small separation between the electrodes leads to reasonable collection efficiencies of ca. 30%. A three-dimensional finite element method (FEM) simulation is developed to predict the current response of these electrodes as a means of estimating the probe geometry. Voltammetric measurements at individual electrodes combined with generation/collection measurements provide a reasonable guide to the electrode size. DCEs are employed in a scanning electrochemical microscopy (SECM) configuration, and their use for both approach curves and imaging is considered. G/C approach curve measurements are shown to be particularly sensitive to the nature of the substrate, with insulating surfaces leading to enhanced collection efficiencies, whereas conducting surfaces lead to a decrease of collection efficiency. As a proof-of-concept, DCEs are further used to locally generate an artificial electron acceptor and to follow the flux of this species and its reduced form during photosynthesis at isolated thylakoid membranes. In addition, 2-dimensional images of a single thylakoid membrane are reported and analyzed to demonstrate the high sensitivity of G/C measurements to localized surface processes. It is finally shown that individual nanometer-size electrodes can be functionalized through the selective deposition of platinum on one of the two electrodes in a DCE while leaving the other one unmodified. This provides an indication of the future versatility of this type of probe for nanoscale measurements and imaging.
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Affiliation(s)
- Kim McKelvey
- Molecular Organisation and Assembly in Cells (MOAC) Doctoral Training Centre, School of Life Sciences, University of Warwick, Coventry, UK
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