1
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Krysiak S, Burda K. The Effect of Removal of External Proteins PsbO, PsbP and PsbQ on Flash-Induced Molecular Oxygen Evolution and Its Biphasicity in Tobacco PSII. Curr Issues Mol Biol 2024; 46:7187-7218. [PMID: 39057069 PMCID: PMC11276211 DOI: 10.3390/cimb46070428] [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: 06/02/2024] [Revised: 06/30/2024] [Accepted: 07/02/2024] [Indexed: 07/28/2024] Open
Abstract
The oxygen evolution within photosystem II (PSII) is one of the most enigmatic processes occurring in nature. It is suggested that external proteins surrounding the oxygen-evolving complex (OEC) not only stabilize it and provide an appropriate ionic environment but also create water channels, which could be involved in triggering the ingress of water and the removal of O2 and protons outside the system. To investigate the influence of these proteins on the rate of oxygen release and the efficiency of OEC function, we developed a measurement protocol for the direct measurement of the kinetics of oxygen release from PSII using a Joliot-type electrode. PSII-enriched tobacco thylakoids were used in the experiments. The results revealed the existence of slow and fast modes of oxygen evolution. This observation is model-independent and requires no specific assumptions about the initial distribution of the OEC states. The gradual removal of exogenous proteins resulted in a slowdown of the rapid phase (~ms) of O2 release and its gradual disappearance while the slow phase (~tens of ms) accelerated. The role of external proteins in regulating the biphasicity and efficiency of oxygen release is discussed based on observed phenomena and current knowledge.
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Affiliation(s)
| | - Kvetoslava Burda
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, al. Mickiewicza 30, 30-059 Krakow, Poland;
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2
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Noguchi T. Mechanism of Proton Transfer through the D1-E65/D2-E312 Gate during Photosynthetic Water Oxidation. J Phys Chem B 2024; 128:1866-1875. [PMID: 38364371 DOI: 10.1021/acs.jpcb.3c07787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
In photosystem II, the D1-E65/D2-E312 dyad in the Cl-1 channel has been proposed to play a pivotal role in proton transfer during water oxidation. However, the precise mechanism remains elusive. Here, the proton transfer mechanism within the Cl-1 channel was investigated using quantum mechanics/molecular mechanics calculations. The molecular vibration of the E65/E312 dyad and its deuteration effect revealed that the recently suggested stepwise proton transfer, i.e., initial proton release from the dyad followed by slow reprotonation, does not occur in the Cl-1 channel. Instead, proton transfer is proposed to take place via a conformational change at the E65/E312 dyad, acting as a gate. In its closed form, a proton is trapped within the dyad, preventing forward proton transfer. This closed form converts into the open form, where protonated D1-E65 provides a hydrogen bond to the water network, thereby facilitating fast Grotthuss-type proton transfer.
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Affiliation(s)
- Takumi Noguchi
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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3
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Drosou M, Pantazis DA. Comprehensive Evaluation of Models for Ammonia Binding to the Oxygen Evolving Complex of Photosystem II. J Phys Chem B 2024; 128:1333-1349. [PMID: 38299511 PMCID: PMC10875651 DOI: 10.1021/acs.jpcb.3c06304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 01/08/2024] [Accepted: 01/17/2024] [Indexed: 02/02/2024]
Abstract
The identity and insertion pathway of the substrate oxygen atoms that are coupled to dioxygen by the oxygen-evolving complex (OEC) remains a central question toward understanding Nature's water oxidation mechanism. In several studies, ammonia has been used as a small "water analogue" to elucidate the pathway of substrate access to the OEC and to aid in determining which of the oxygen ligands of the tetramanganese cluster are substrates for O-O bond formation. On the basis of structural and spectroscopic investigations, five first-sphere binding modes of ammonia have been suggested, involving either substitution of an existing H2O/OH-/O2- group or addition as an extra ligand to a metal ion of the Mn4CaO5 cluster. Some of these modes, specifically the ones involving substitution, have already been subject to spectroscopy-oriented quantum chemical investigations, whereas more recent suggestions that postulate the addition of ammonia have not been examined so far with quantum chemistry for their agreement with spectroscopic data. Herein, we use a common structural framework and theoretical methodology to evaluate structural models of the OEC that represent all proposed modes of first-sphere ammonia interaction with the OEC in its S2 state. Criteria include energetic, magnetic, kinetic, and spectroscopic properties compared against available experimental EPR, ENDOR, ESEEM, and EDNMR data. Our results show that models featuring ammonia replacing one of the two terminal water ligands on Mn4 align best with experimental data, while they definitively exclude substitution of a bridging μ-oxo ligand as well as incorporation of ammonia as a sixth ligand on Mn1 or Mn4.
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Affiliation(s)
- Maria Drosou
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
- Inorganic
Chemistry Laboratory, National and Kapodistrian
University of Athens, Panepistimiopolis, Zografou 15771, Greece
| | - Dimitrios A. Pantazis
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
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4
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Saito K, Nishio S, Ishikita H. Interplay of two low-barrier hydrogen bonds in long-distance proton-coupled electron transfer for water oxidation. PNAS NEXUS 2023; 2:pgad423. [PMID: 38130665 PMCID: PMC10733176 DOI: 10.1093/pnasnexus/pgad423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 11/20/2023] [Indexed: 12/23/2023]
Abstract
D1-Tyr161 (TyrZ) forms a low-barrier H-bond with D1-His190 and functions as a redox-active group in photosystem II. When oxidized to the radical form (TyrZ-O•), it accepts an electron from the oxygen-evolving Mn4CaO5 cluster, facilitating an increase in the oxidation state (Sn; n = 0-3). In this study, we investigated the mechanism of how TyrZ-O• drives proton-coupled electron transfer during the S2 to S3 transition using a quantum mechanical/molecular mechanical approach. In response to TyrZ-O• formation and subsequent loss of the low-barrier H-bond, the ligand water molecule at the Ca2+ site (W4) reorients away from TyrZ and donates an H-bond to D1-Glu189 at Mn4 of Mn4CaO5 together with an adjacent water molecule. The H-bond donation to the Mn4CaO5 cluster triggers the release of the proton from the lowest pKa site (W1 at Mn4) along the W1…D1-Asp61 low-barrier H-bond, leading to protonation of D1-Asp61. The interplay of the two low-barrier H-bonds, involving the Ca2+ interface and forming the extended Grotthuss-like network [TyrZ…D1-His190]-[Mn4CaO5]-[W1…D1-Asp61], rather than the direct electrostatic interaction, is likely a basis of the apparent long-distance interaction (11.4 Å) between TyrZ-O• formation and D1-Asp61 protonation.
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Affiliation(s)
- Keisuke Saito
- Department of Applied Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Shunya Nishio
- Department of Applied Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Hiroshi Ishikita
- Department of Applied Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8654, Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
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5
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Gates C, Williams JM, Ananyev G, Dismukes GC. How chloride functions to enable proton conduction in photosynthetic water oxidation: Time-resolved kinetics of intermediates (S-states) in vivo and bromide substitution. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148998. [PMID: 37499962 DOI: 10.1016/j.bbabio.2023.148998] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/11/2023] [Accepted: 07/19/2023] [Indexed: 07/29/2023]
Abstract
Chloride (Cl-) is essential for O2 evolution during photosynthetic water oxidation. Two chlorides near the water-oxidizing complex (WOC) in Photosystem II (PSII) structures from Thermosynechococcus elongatus (and T. vulcanus) have been postulated to transfer protons generated from water oxidation. We monitored four criteria: primary charge separation flash yield (P* → P+QA-), rates of water oxidation steps (S-states), rate of proton evolution, and flash O2 yield oscillations by measuring chlorophyll variable fluorescence (P* quenching), pH-sensitive dye changes, and oximetry. Br-substitution slows and destabilizes cellular growth, resulting from lower light-saturated O2 evolution rate (-20 %) and proton release (-36 % ΔpH gradient). The latter implies less ATP production. In Br- cultures, protonogenic S-state transitions (S2 → S3 → S0') slow with increasing light intensity and during O2/water exchange (S0' → S0 → S1), while the non-protonogenic S1 → S2 transition is kinetically unaffected. As flash rate increases in Cl- cultures, both rate and extent of acidification of the lumen increase, while charge recombination is suppressed relative to Br-. The Cl- advantage in rapid proton escape from the WOC to lumen is attributed to correlated ion-pair movement of H3O+Cl- in dry water channels vs. separated Br- and H+ ion movement through different regions (>200-fold difference in Bronsted acidities). By contrast, at low flash rates a previously unreported reversal occurs that favors Br- cultures for both proton evolution and less PSII charge recombination. In Br- cultures, slower proton transfer rate is attributed to stronger ion-pairing of Br- with AA residues lining the water channels. Both anions charge-neutralize protons and shepherd them to the lumen using dry aqueous channels.
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Affiliation(s)
- Colin Gates
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, NJ 08854, USA; Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, NJ 08854, USA; Department of Computational Biology and Molecular Biophysics, Rutgers, The State University of New Jersey, NJ 08854, USA; Department of Chemistry and Biochemistry, Loyola University Chicago, IL 60660, USA
| | - Jonah M Williams
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, NJ 08854, USA; Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, NJ 08854, USA
| | - Gennady Ananyev
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, NJ 08854, USA; Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, NJ 08854, USA
| | - G Charles Dismukes
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, NJ 08854, USA; Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, NJ 08854, USA.
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6
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Shevela D, Kern JF, Govindjee G, Messinger J. Solar energy conversion by photosystem II: principles and structures. PHOTOSYNTHESIS RESEARCH 2023; 156:279-307. [PMID: 36826741 PMCID: PMC10203033 DOI: 10.1007/s11120-022-00991-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 12/01/2022] [Indexed: 05/23/2023]
Abstract
Photosynthetic water oxidation by Photosystem II (PSII) is a fascinating process because it sustains life on Earth and serves as a blue print for scalable synthetic catalysts required for renewable energy applications. The biophysical, computational, and structural description of this process, which started more than 50 years ago, has made tremendous progress over the past two decades, with its high-resolution crystal structures being available not only of the dark-stable state of PSII, but of all the semi-stable reaction intermediates and even some transient states. Here, we summarize the current knowledge on PSII with emphasis on the basic principles that govern the conversion of light energy to chemical energy in PSII, as well as on the illustration of the molecular structures that enable these reactions. The important remaining questions regarding the mechanism of biological water oxidation are highlighted, and one possible pathway for this fundamental reaction is described at a molecular level.
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Affiliation(s)
- Dmitry Shevela
- Department of Chemistry, Chemical Biological Centre, Umeå University, 90187, Umeå, Sweden.
| | - Jan F Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Govindjee Govindjee
- Department of Plant Biology, Department of Biochemistry and Center of Biophysics & Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Johannes Messinger
- Department of Chemistry, Chemical Biological Centre, Umeå University, 90187, Umeå, Sweden.
- Molecular Biomimetics, Department of Chemistry - Ångström, Uppsala University, 75120, Uppsala, Sweden.
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7
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Sirohiwal A, Pantazis DA. Functional Water Networks in Fully Hydrated Photosystem II. J Am Chem Soc 2022; 144:22035-22050. [PMID: 36413491 PMCID: PMC9732884 DOI: 10.1021/jacs.2c09121] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Water channels and networks within photosystem II (PSII) of oxygenic photosynthesis are critical for enzyme structure and function. They control substrate delivery to the oxygen-evolving center and mediate proton transfer at both the oxidative and reductive endpoints. Current views on PSII hydration are derived from protein crystallography, but structural information may be compromised by sample dehydration and technical limitations. Here, we simulate the physiological hydration structure of a cyanobacterial PSII model following a thorough hydration procedure and large-scale unconstrained all-atom molecular dynamics enabled by massively parallel simulations. We show that crystallographic models of PSII are moderately to severely dehydrated and that this problem is particularly acute for models derived from X-ray free electron laser (XFEL) serial femtosecond crystallography. We present a fully hydrated representation of cyanobacterial PSII and map all water channels, both static and dynamic, associated with the electron donor and acceptor sides. Among them, we describe a series of transient channels and the attendant conformational gating role of protein components. On the acceptor side, we characterize a channel system that is absent from existing crystallographic models but is likely functionally important for the reduction of the terminal electron acceptor plastoquinone QB. The results of the present work build a foundation for properly (re)evaluating crystallographic models and for eliciting new insights into PSII structure and function.
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8
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Nakajima Y, Ugai-Amo N, Tone N, Nakagawa A, Iwai M, Ikeuchi M, Sugiura M, Suga M, Shen JR. Crystal structures of photosystem II from a cyanobacterium expressing psbA 2 in comparison to psbA 3 reveal differences in the D1 subunit. J Biol Chem 2022; 298:102668. [PMID: 36334624 PMCID: PMC9709244 DOI: 10.1016/j.jbc.2022.102668] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/27/2022] [Accepted: 10/30/2022] [Indexed: 11/07/2022] Open
Abstract
Three psbA genes (psbA1, psbA2, and psbA3) encoding the D1 subunit of photosystem II (PSII) are present in the thermophilic cyanobacterium Thermosynechococcus elongatus and are expressed differently in response to changes in the growth environment. To clarify the functional differences of the D1 protein expressed from these psbA genes, PSII dimers from two strains, each expressing only one psbA gene (psbA2 or psbA3), were crystallized, and we analyzed their structures at resolutions comparable to previously studied PsbA1-PSII. Our results showed that the hydrogen bond between pheophytin/D1 (PheoD1) and D1-130 became stronger in PsbA2- and PsbA3-PSII due to change of Gln to Glu, which partially explains the increase in the redox potential of PheoD1 observed in PsbA3. In PsbA2, one hydrogen bond was lost in PheoD1 due to the change of D1-Y147F, which may explain the decrease in stability of PheoD1 in PsbA2. Two water molecules in the Cl-1 channel were lost in PsbA2 due to the change of D1-P173M, leading to the narrowing of the channel, which may explain the lower efficiency of the S-state transition beyond S2 in PsbA2-PSII. In PsbA3-PSII, a hydrogen bond between D1-Ser270 and a sulfoquinovosyl-diacylglycerol molecule near QB disappeared due to the change of D1-Ser270 in PsbA1 and PsbA2 to D1-Ala270. This may result in an easier exchange of bound QB with free plastoquinone, hence an enhancement of oxygen evolution in PsbA3-PSII due to its high QB exchange efficiency. These results provide a structural basis for further functional examination of the three PsbA variants.
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Affiliation(s)
- Yoshiki Nakajima
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, Japan
| | - Natsumi Ugai-Amo
- Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Naoki Tone
- Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Akiko Nakagawa
- Proteo-Science Research Center, Ehime University, Matsuyama, Japan
| | - Masako Iwai
- Graduate School and College of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Masahiko Ikeuchi
- Graduate School and College of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Miwa Sugiura
- Proteo-Science Research Center, Ehime University, Matsuyama, Japan
| | - Michihiro Suga
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, Japan,Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan,For correspondence: Michihiro Suga; Jian-Ren Shen
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, Japan,Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan,For correspondence: Michihiro Suga; Jian-Ren Shen
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9
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Shimada Y, Sugiyama A, Nagao R, Noguchi T. Role of D1-Glu65 in Proton Transfer during Photosynthetic Water Oxidation in Photosystem II. J Phys Chem B 2022; 126:8202-8213. [PMID: 36199221 DOI: 10.1021/acs.jpcb.2c05869] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Photosynthetic water oxidation takes place at the Mn4CaO5 cluster in photosystem II (PSII) through a light-driven cycle of five intermediates called S states (S0-S4). Although the PSII structures have shown the presence of several channels around the Mn4CaO5 cluster leading to the lumen, the pathways for proton release in the individual S-state transitions remain unidentified. Here, we studied the involvement of the so-called Cl channel in proton transfer during water oxidation by examining the effect of the mutation of D1-Glu65, a key residue in this channel, to Ala using Fourier transform infrared difference and time-resolved infrared spectroscopies together with thermoluminescence and delayed luminescence measurements. It was shown that the structure and the redox property of the catalytic site were little affected by the D1-Glu65Ala mutation. In the S2 → S3 transition, the efficiency was still high and the transition rate was only moderately retarded in the D1-Glu65Ala mutant. In contrast, the S3 → S0 transition was significantly inhibited by this mutation. These results suggest that proton transfer in the S2 → S3 transition occurs through multiple pathways including the Cl channel, whereas this channel likely serves as a single pathway for proton exit in the S3 → S0 transition.
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Affiliation(s)
- Yuichiro Shimada
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya464-8602, Japan
| | - Ayane Sugiyama
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya464-8602, Japan
| | - Ryo Nagao
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya464-8602, Japan.,Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Okayama700-8530, Japan
| | - Takumi Noguchi
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya464-8602, Japan
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10
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Imaizumi K, Ifuku K. Binding and functions of the two chloride ions in the oxygen-evolving center of photosystem II. PHOTOSYNTHESIS RESEARCH 2022; 153:135-156. [PMID: 35698013 DOI: 10.1007/s11120-022-00921-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
Light-driven water oxidation in photosynthesis occurs at the oxygen-evolving center (OEC) of photosystem II (PSII). Chloride ions (Cl-) are essential for oxygen evolution by PSII, and two Cl- ions have been found to specifically bind near the Mn4CaO5 cluster in the OEC. The retention of these Cl- ions within the OEC is critically supported by some of the membrane-extrinsic subunits of PSII. The functions of these two Cl- ions and the mechanisms of their retention both remain to be fully elucidated. However, intensive studies performed recently have advanced our understanding of the functions of these Cl- ions, and PSII structures from various species have been reported, aiding the interpretation of previous findings regarding Cl- retention by extrinsic subunits. In this review, we summarize the findings to date on the roles of the two Cl- ions bound within the OEC. Additionally, together with a short summary of the functions of PSII membrane-extrinsic subunits, we discuss the mechanisms of Cl- retention by these extrinsic subunits.
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Affiliation(s)
- Ko Imaizumi
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan
| | - Kentaro Ifuku
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan.
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11
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Barnum TP, Coates JD. The biogeochemical cycling of chlorine. GEOBIOLOGY 2022; 20:634-649. [PMID: 35851523 DOI: 10.1111/gbi.12513] [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: 10/18/2021] [Revised: 05/24/2022] [Accepted: 06/26/2022] [Indexed: 06/15/2023]
Abstract
Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from -1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth.
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Affiliation(s)
- Tyler P Barnum
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
| | - John D Coates
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
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12
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Sugo Y, Saito K, Ishikita H. Conformational Changes and H-Bond Rearrangements during Quinone Release in Photosystem II. Biochemistry 2022; 61:1836-1843. [PMID: 35914244 PMCID: PMC9454826 DOI: 10.1021/acs.biochem.2c00324] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In photosystem II (PSII) and photosynthetic reaction centers from purple bacteria (PbRC), the electron released from the electronically excited chlorophyll is transferred to the terminal electron acceptor quinone, QB. QB accepts two electrons and two protons before leaving the protein. We investigated the molecular mechanism of quinone exchange in PSII, conducting molecular dynamics (MD) simulations and quantum mechanical/molecular mechanical (QM/MM) calculations. MD simulations suggest that the release of QB leads to the transformation of the short helix (D1-Phe260 to D1-Ser264), which is adjacent to the stromal helix de (D1-Asn247 to D1-Ile259), into a loop and to the formation of a water-intake channel. Water molecules enter the QB binding pocket via the channel and form an H-bond network. QM/MM calculations indicate that the H-bond network serves as a proton-transfer pathway for the reprotonation of D1-His215, the proton donor during QBH-/QBH2 conversion. Together with the absence of the corresponding short helix but the presence of Glu-L212 in PbRC, it seems likely that the two type-II reaction centers undergo quinone exchange via different mechanisms.
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Affiliation(s)
- Yu Sugo
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Keisuke Saito
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.,Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Hiroshi Ishikita
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.,Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
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13
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Imaizumi K, Nishimura T, Nagao R, Saito K, Nakano T, Ishikita H, Noguchi T, Ifuku K. D139N mutation of PsbP enhances the oxygen-evolving activity of photosystem II through stabilized binding of a chloride ion. PNAS NEXUS 2022; 1:pgac136. [PMID: 36741451 PMCID: PMC9896922 DOI: 10.1093/pnasnexus/pgac136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 07/19/2022] [Indexed: 02/07/2023]
Abstract
Photosystem II (PSII) is a multisubunit membrane protein complex that catalyzes light-driven oxidation of water to molecular oxygen. The chloride ion (Cl-) has long been known as an essential cofactor for oxygen evolution by PSII, and two Cl- ions (Cl-1 and Cl-2) have been found to specifically bind near the Mn4CaO5 cluster within the oxygen-evolving center (OEC). However, despite intensive studies on these Cl- ions, little is known about the function of Cl-2, the Cl- ion that is associated with the backbone nitrogens of D1-Asn338, D1-Phe339, and CP43-Glu354. In green plant PSII, the membrane extrinsic subunits-PsbP and PsbQ-are responsible for Cl- retention within the OEC. The Loop 4 region of PsbP, consisting of highly conserved residues Thr135-Gly142, is inserted close to Cl-2, but its importance has not been examined to date. Here, we investigated the importance of PsbP-Loop 4 using spinach PSII membranes reconstituted with spinach PsbP proteins harboring mutations in this region. Mutations in PsbP-Loop 4 had remarkable effects on the rate of oxygen evolution by PSII. Moreover, we found that a specific mutation, PsbP-D139N, significantly enhances the oxygen-evolving activity in the absence of PsbQ, but not significantly in its presence. The D139N mutation increased the Cl- retention ability of PsbP and induced a unique structural change in the OEC, as indicated by light-induced Fourier transform infrared (FTIR) difference spectroscopy and theoretical calculations. Our findings provide insight into the functional significance of Cl-2 in the water-oxidizing reaction of PSII.
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Affiliation(s)
- Ko Imaizumi
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Taishi Nishimura
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Ryo Nagao
- Division of Material Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan,Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Keisuke Saito
- Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan,Department of Applied Chemistry, The University of Tokyo, Tokyo 113-8654 , Japan
| | - Takeshi Nakano
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Hiroshi Ishikita
- Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan,Department of Applied Chemistry, The University of Tokyo, Tokyo 113-8654 , Japan
| | - Takumi Noguchi
- Division of Material Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
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14
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Guo Y, Messinger J, Kloo L, Sun L. Reversible Structural Isomerization of Nature's Water Oxidation Catalyst Prior to O-O Bond Formation. J Am Chem Soc 2022; 144:11736-11747. [PMID: 35748306 PMCID: PMC9264352 DOI: 10.1021/jacs.2c03528] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
![]()
Photosynthetic water
oxidation is catalyzed by a manganese–calcium
oxide cluster, which experiences five “S-states” during
a light-driven reaction cycle. The unique “distorted chair”-like
geometry of the Mn4CaO5(6) cluster shows structural
flexibility that has been frequently proposed to involve “open”
and “closed”-cubane forms from the S1 to
S3 states. The isomers are interconvertible in the S1 and S2 states, while in the S3 state,
the open-cubane structure is observed to dominate inThermosynechococcus elongatus (cyanobacteria) samples.
In this work, using density functional theory calculations, we go
beyond the S3+Yz state to the S3nYz• → S4+Yz step, and report for the first time
that the reversible isomerism, which is suppressed in the S3+Yz state, is fully recovered
in the ensuing S3nYz• state due to the proton release
from a manganese-bound water ligand. The altered coordination strength
of the manganese–ligand facilitates formation of the closed-cubane
form, in a dynamic equilibrium with the open-cubane form. This tautomerism
immediately preceding dioxygen formation may constitute the rate limiting
step for O2 formation, and exert a significant influence
on the water oxidation mechanism in photosystem II.
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Affiliation(s)
- Yu Guo
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Johannes Messinger
- Department of Chemistry, Umeå University, Linnaeus väg 6 (KBC huset), SE-90187 Umeå, Sweden.,Molecular Biomimetics, Department of Chemistry─Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
| | - Lars Kloo
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Licheng Sun
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
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15
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Boussac A, Sugiura M, Sellés J. Probing the proton release by Photosystem II in the S 1 to S 2 high-spin transition. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148546. [PMID: 35337840 DOI: 10.1016/j.bbabio.2022.148546] [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: 01/11/2022] [Revised: 02/24/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
The stoichiometry and kinetics of the proton release were investigated during each transition of the S-state cycle in Photosystem II (PSII) from Thermosynechococcus elongatus containing either a Mn4CaO5 (PSII/Ca) or a Mn4SrO5 (PSII/Sr) cluster. The measurements were done at pH 6.0 and pH 7.0 knowing that, in PSII/Ca at pH 6.0 and pH 7.0 and in PSII/Sr at pH 6.0, the flash-induced S2-state is in a low-spin configuration (S2LS) whereas in PSII/Sr at pH 7.0, the S2-state is in a high-spin configuration (S2HS) in half of the centers. Two measurements were done; the time-resolved flash dependent i) absorption of either bromocresol purple at pH 6.0 or neutral red at pH 7.0 and ii) electrochromism in the Soret band of PD1 at 440 nm. The fittings of the oscillations with a period of four indicate that one proton is released in the S1 to S2HS transition in PSII/Sr at pH 7.0. It has previously been suggested that the proton released in the S2LS to S3 transition would be released in a S2LSTyrZ• → S2HSTyrZ• transition before the electron transfer from the cluster to TyrZ• occurs. The release of a proton in the S1TyrZ• → S2HSTyrZ transition would logically imply that this proton release is missing in the S2HSTyrZ• to S3TyrZ transition. Instead, the proton release in the S1 to S2HS transition in PSII/Sr at pH 7.0 was mainly done at the expense of the proton release in the S3 to S0 and S0 to S1 transitions. However, at pH 7.0, the electrochromism of PD1 seems larger in PSII/Sr when compared to PSII/Ca in the S3 state. This points to the complex link between proton movements in and immediately around the Mn4 cluster and the mechanism leading to the release of protons into the bulk.
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Affiliation(s)
- Alain Boussac
- I(2)BC, UMR CNRS 9198, CEA Saclay, 91191 Gif-sur-Yvette, France.
| | - Miwa Sugiura
- Proteo-Science Research Center, Department of Chemistry, Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Julien Sellés
- Institut de Biologie Physico-Chimique, UMR CNRS 7141 and Sorbonne Université, 13 rue Pierre et Marie Curie, 75005 Paris, France
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16
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Yocum CF. Photosystem 2 and the oxygen evolving complex: a brief overview. PHOTOSYNTHESIS RESEARCH 2022; 152:97-105. [PMID: 35294671 DOI: 10.1007/s11120-022-00910-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
These special issues of photosynthesis research present papers documenting progress in revealing the many aspects of photosystem 2, a unique, one-of-a-kind complex system that can reduce a plastoquinone to a plastoquinol on every second flash of light and oxidize 2 H2O to an O2 on every fourth flash. This overview is a brief personal assessment of the progress observed by the author over a four-decade research career, including a discussion of some remaining unsolved issues. It will come as no surprise to readers that there are remaining questions given the complexity of PS2, and the efforts that have been needed so far to uncover its secrets. In fact, most readers will have their own lists of outstanding questions.
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Affiliation(s)
- Charles F Yocum
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
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17
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Allgöwer F, Gamiz-Hernandez AP, Rutherford AW, Kaila VRI. Molecular Principles of Redox-Coupled Protonation Dynamics in Photosystem II. J Am Chem Soc 2022; 144:7171-7180. [PMID: 35421304 PMCID: PMC9052759 DOI: 10.1021/jacs.1c13041] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Photosystem II (PSII) catalyzes light-driven water oxidization, releasing O2 into the atmosphere and transferring the electrons for the synthesis of biomass. However, despite decades of structural and functional studies, the water oxidation mechanism of PSII has remained puzzling and a major challenge for modern chemical research. Here, we show that PSII catalyzes redox-triggered proton transfer between its oxygen-evolving Mn4O5Ca cluster and a nearby cluster of conserved buried ion-pairs, which are connected to the bulk solvent via a proton pathway. By using multi-scale quantum and classical simulations, we find that oxidation of a redox-active Tyrz (Tyr161) lowers the reaction barrier for the water-mediated proton transfer from a Ca2+-bound water molecule (W3) to Asp61 via conformational changes in a nearby ion-pair (Asp61/Lys317). Deprotonation of this W3 substrate water triggers its migration toward Mn1 to a position identified in recent X-ray free-electron laser (XFEL) experiments [Ibrahim et al. Proc. Natl. Acad. Sci. USA 2020, 117, 12,624-12,635]. Further oxidation of the Mn4O5Ca cluster lowers the proton transfer barrier through the water ligand sphere of the Mn4O5Ca cluster to Asp61 via a similar ion-pair dissociation process, while the resulting Mn-bound oxo/oxyl species leads to O2 formation by a radical coupling mechanism. The proposed redox-coupled protonation mechanism shows a striking resemblance to functional motifs in other enzymes involved in biological energy conversion, with an interplay between hydration changes, ion-pair dynamics, and electric fields that modulate the catalytic barriers.
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Affiliation(s)
- Friederike Allgöwer
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
| | - Ana P Gamiz-Hernandez
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
| | - A William Rutherford
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
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18
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Mandal M, Saito K, Ishikita H. Requirement of Chloride for the Downhill Electron Transfer Pathway from the Water-Splitting Center in Natural Photosynthesis. J Phys Chem B 2021; 126:123-131. [PMID: 34955014 DOI: 10.1021/acs.jpcb.1c09176] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In photosystem II (PSII), Cl- is a prerequisite for the second flash-induced oxidation of the Mn4CaO5 cluster (the S2 to S3 transition). We report proton transfer from the substrate water molecule via D1-Asp61 and electron transfer via redox-active D1-Tyr161 (TyrZ) to the chlorophyll pair in Cl--depleted PSII using a quantum mechanical/molecular mechanical approach. The low-barrier H-bond formation between the substrate water molecule and D1-Asp61 remained unaffected upon the depletion of Cl-. However, the binding site, D2-Lys317, formed a salt bridge with D1-Asp61, leading to the inhibition of the subsequent proton transfer. Remarkably, the redox potential (Em) of S2/S3 increased significantly, making electron transfer from S2 to TyrZ energetically uphill, as observed in Ca2+-depleted PSII. The uphill electron transfer pathway was induced by the significant increase in Em(S2/S3) caused by the loss of charge compensation for D2-Lys317 upon the depletion of Cl-, whereas it was induced by the significant decrease in Em(TyrZ) caused by the rearrangement of the water molecules at the Ca2+ binding moiety upon the depletion of Ca2+.
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Affiliation(s)
- Manoj Mandal
- Department of Chemical, Biological & Macro-Molecular Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata, West Bengal 700106, India
| | - Keisuke Saito
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.,Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Hiroshi Ishikita
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.,Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
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19
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Narzi D, Guidoni L. Structural and dynamic insights into Mn 4Ca cluster-depleted Photosystem II. Phys Chem Chem Phys 2021; 23:27428-27436. [PMID: 34860219 DOI: 10.1039/d1cp02367e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the first steps of natural oxygenic photosynthesis, sunlight is used to oxidize water molecules to protons, electrons and molecular oxygen. This reaction takes place on the Mn4Ca cluster located in the reaction centre of Photosystem II (PSII), where the cluster is assembled and continuously repaired through a process known as photoactivation. Understanding the molecular details of such a process has important implications in different fields, in particular inspiring synthesis and repair strategies for artificial photosynthesis devices. In this regard, a detailed structural and dynamic characterization of Photosystem II lacking a Mn4Ca cluster, namely apo PSII, is a prerequisite for the full comprehension of the photoactivation. Recently, the structure of the apo PSII was resolved at 2.55 Å resolution [Zhang et al., eLife, 2017, 6, e26933], suggesting a pre-organized structure of the protein cavity hosting the cluster. Anyway, the question of whether these findings are a feature of the method used remains open. Here, by means of classical Molecular Dynamics simulations, we characterized the structural and dynamic features of the apo PSII for different protonation states of the cluster cavity. Albeit an overall conformational stability common to all investigated systems, we found significant deviations in the conformation of the side chains of the active site with respect to the X-ray positions. Our findings suggest that not all residues acting as Mn ligands are pre-organized prior to the Mn4Ca formation and previous local conformational changes are required in order to bind the first Mn ion in the high-affinity binding site.
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Affiliation(s)
- Daniele Narzi
- Department of Physical and Chemical Science, Università dellAquila, LAquila, Italy.
| | - Leonardo Guidoni
- Department of Physical and Chemical Science, Università dellAquila, LAquila, Italy.
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20
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Hussein R, Ibrahim M, Bhowmick A, Simon PS, Chatterjee R, Lassalle L, Doyle M, Bogacz I, Kim IS, Cheah MH, Gul S, de Lichtenberg C, Chernev P, Pham CC, Young ID, Carbajo S, Fuller FD, Alonso-Mori R, Batyuk A, Sutherlin KD, Brewster AS, Bolotovsky R, Mendez D, Holton JM, Moriarty NW, Adams PD, Bergmann U, Sauter NK, Dobbek H, Messinger J, Zouni A, Kern J, Yachandra VK, Yano J. Structural dynamics in the water and proton channels of photosystem II during the S 2 to S 3 transition. Nat Commun 2021; 12:6531. [PMID: 34764256 PMCID: PMC8585918 DOI: 10.1038/s41467-021-26781-z] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 10/21/2021] [Indexed: 11/30/2022] Open
Abstract
Light-driven oxidation of water to molecular oxygen is catalyzed by the oxygen-evolving complex (OEC) in Photosystem II (PS II). This multi-electron, multi-proton catalysis requires the transport of two water molecules to and four protons from the OEC. A high-resolution 1.89 Å structure obtained by averaging all the S states and refining the data of various time points during the S2 to S3 transition has provided better visualization of the potential pathways for substrate water insertion and proton release. Our results indicate that the O1 channel is the likely water intake pathway, and the Cl1 channel is the likely proton release pathway based on the structural rearrangements of water molecules and amino acid side chains along these channels. In particular in the Cl1 channel, we suggest that residue D1-E65 serves as a gate for proton transport by minimizing the back reaction. The results show that the water oxidation reaction at the OEC is well coordinated with the amino acid side chains and the H-bonding network over the entire length of the channels, which is essential in shuttling substrate waters and protons.
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Affiliation(s)
- Rana Hussein
- grid.7468.d0000 0001 2248 7639Institut für Biologie, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Mohamed Ibrahim
- grid.7468.d0000 0001 2248 7639Institut für Biologie, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Asmit Bhowmick
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Philipp S. Simon
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Ruchira Chatterjee
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Louise Lassalle
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Margaret Doyle
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Isabel Bogacz
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - In-Sik Kim
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Mun Hon Cheah
- grid.8993.b0000 0004 1936 9457Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120 Uppsala, Sweden
| | - Sheraz Gul
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Casper de Lichtenberg
- grid.8993.b0000 0004 1936 9457Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120 Uppsala, Sweden ,grid.12650.300000 0001 1034 3451Department of Chemistry, Umeå University, SE 90187 Umeå, Sweden
| | - Petko Chernev
- grid.8993.b0000 0004 1936 9457Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120 Uppsala, Sweden
| | - Cindy C. Pham
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Iris D. Young
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Sergio Carbajo
- grid.512023.70000 0004 6047 9447Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA
| | - Franklin D. Fuller
- grid.512023.70000 0004 6047 9447Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA
| | - Roberto Alonso-Mori
- grid.512023.70000 0004 6047 9447Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA
| | - Alex Batyuk
- grid.512023.70000 0004 6047 9447Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA
| | - Kyle D. Sutherlin
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Aaron S. Brewster
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Robert Bolotovsky
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Derek Mendez
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - James M. Holton
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Nigel W. Moriarty
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Paul D. Adams
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA ,grid.47840.3f0000 0001 2181 7878Department of Bioengineering, University of California, Berkeley, CA 94720 USA
| | - Uwe Bergmann
- grid.14003.360000 0001 2167 3675Department of Physics, University of Wisconsin–Madison, Madison, WI 53706 USA
| | - Nicholas K. Sauter
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Holger Dobbek
- grid.7468.d0000 0001 2248 7639Institut für Biologie, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Johannes Messinger
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120, Uppsala, Sweden. .,Department of Chemistry, Umeå University, SE 90187, Umeå, Sweden.
| | - Athina Zouni
- Institut für Biologie, Humboldt-Universität zu Berlin, 10115, Berlin, Germany.
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Vittal K. Yachandra
- grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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21
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Okamoto Y, Shimada Y, Nagao R, Noguchi T. Proton and Water Transfer Pathways in the S 2 → S 3 Transition of the Water-Oxidizing Complex in Photosystem II: Time-Resolved Infrared Analysis of the Effects of D1-N298A Mutation and NO 3- Substitution. J Phys Chem B 2021; 125:6864-6873. [PMID: 34152151 DOI: 10.1021/acs.jpcb.1c03386] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Photosynthetic water oxidation is performed through a light-driven cycle of five intermediates (S0-S4 states) in photosystem II (PSII). The S2 → S3 transition, which involves concerted water and proton transfer, is a key process for understanding the water oxidation mechanism. Here, to identify the water and proton transfer pathways during the S2 → S3 transition, we examined the effects of D1-N298A mutation and NO3- substitution for Cl-, which perturbed the O1 and Cl channels, respectively, on the S2 → S3 kinetics using time-resolved infrared spectroscopy. The S2 → S3 transition was retarded both upon NO3- substitution and upon D1-N298A mutation, whereas it was unaffected by further NO3- substitution in N298A PSII. The H/D kinetic isotope effect in N298A PSII was relatively small, revealing that water transfer is a rate-limiting step in this mutant. From these results, it was suggested that during the S2 → S3 transition, water delivery and proton release occur through the O1 and Cl channels, respectively.
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Affiliation(s)
- Yasutada Okamoto
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Yuichiro Shimada
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Ryo Nagao
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Takumi Noguchi
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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22
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Kaur D, Khaniya U, Zhang Y, Gunner MR. Protein Motifs for Proton Transfers That Build the Transmembrane Proton Gradient. Front Chem 2021; 9:660954. [PMID: 34211960 PMCID: PMC8239185 DOI: 10.3389/fchem.2021.660954] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/31/2021] [Indexed: 11/13/2022] Open
Abstract
Biological membranes are barriers to polar molecules, so membrane embedded proteins control the transfers between cellular compartments. Protein controlled transport moves substrates and activates cellular signaling cascades. In addition, the electrochemical gradient across mitochondrial, bacterial and chloroplast membranes, is a key source of stored cellular energy. This is generated by electron, proton and ion transfers through proteins. The gradient is used to fuel ATP synthesis and to drive active transport. Here the mechanisms by which protons move into the buried active sites of Photosystem II (PSII), bacterial RCs (bRCs) and through the proton pumps, Bacteriorhodopsin (bR), Complex I and Cytochrome c oxidase (CcO), are reviewed. These proteins all use water filled proton transfer paths. The proton pumps, that move protons uphill from low to high concentration compartments, also utilize Proton Loading Sites (PLS), that transiently load and unload protons and gates, which block backflow of protons. PLS and gates should be synchronized so PLS proton affinity is high when the gate opens to the side with few protons and low when the path is open to the high concentration side. Proton transfer paths in the proteins we describe have different design features. Linear paths are seen with a unique entry and exit and a relatively straight path between them. Alternatively, paths can be complex with a tangle of possible routes. Likewise, PLS can be a single residue that changes protonation state or a cluster of residues with multiple charge and tautomer states.
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Affiliation(s)
- Divya Kaur
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY, United States.,Department of Physics, City College of New York, New York, NY, United States
| | - Umesh Khaniya
- Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
| | - Yingying Zhang
- Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
| | - M R Gunner
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY, United States.,Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
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23
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Kaur D, Zhang Y, Reiss KM, Mandal M, Brudvig GW, Batista VS, Gunner MR. Proton exit pathways surrounding the oxygen evolving complex of photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148446. [PMID: 33964279 DOI: 10.1016/j.bbabio.2021.148446] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 12/17/2022]
Abstract
Photosystem II allows water to be the primary electron source for the photosynthetic electron transfer chain. Water is oxidized to dioxygen at the Oxygen Evolving Complex (OEC), a Mn4CaO5 inorganic core embedded on the lumenal side of PSII. Water-filled channels surrounding the OEC must bring in substrate water molecules, remove the product protons to the lumen, and may transport the product oxygen. Three water-filled channels, denoted large, narrow, and broad, extend from the OEC towards the aqueous surface more than 15 Å away. However, the role of each pathway in the transport in and out of the OEC is yet to be established. Here, we combine Molecular Dynamics (MD), Multi Conformation Continuum Electrostatics (MCCE) and Network Analysis to compare and contrast the three potential proton transfer paths. Hydrogen bond network analysis shows that near the OEC the waters are highly interconnected with similar free energy for hydronium at all locations. The paths diverge as they move towards the lumen. The water chain in the broad channel is better connected than in the narrow and large channels, where disruptions in the network are observed approximately 10 Å from the OEC. In addition, the barrier for hydronium translocation is lower in the broad channel. Thus, a proton released from any location on the OEC can access all paths, but the likely exit to the lumen passes through PsbO via the broad channel.
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Affiliation(s)
- Divya Kaur
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY 10016, United States; Department of Physics, City College of New York, NY 10031, United States
| | - Yingying Zhang
- Department of Physics, City College of New York, NY 10031, United States; Department of Physics, The Graduate Center of the City University of New York, New York, NY 10016, United States
| | - Krystle M Reiss
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | - Manoj Mandal
- Department of Physics, City College of New York, NY 10031, United States
| | - Gary W Brudvig
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, CT 06520, United States
| | - M R Gunner
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY 10016, United States; Department of Physics, City College of New York, NY 10031, United States; Department of Physics, The Graduate Center of the City University of New York, New York, NY 10016, United States.
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24
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Mandal M, Saito K, Ishikita H. Two Distinct Oxygen-Radical Conformations in the X-ray Free Electron Laser Structures of Photosystem II. J Phys Chem Lett 2021; 12:4032-4037. [PMID: 33881870 DOI: 10.1021/acs.jpclett.1c00814] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report the existence of two distinct oxygen-radical-containing Mn4CaO5/6 conformations with short O···O bonds in the crystal structures of the oxygen-evolving enzyme photosystem II (PSII), obtained using an X-ray free electron laser (XFEL). A short O···O distance of <2.3 Å between the O4 site of the Mn4CaO5 complex and the adjacent water molecule (W539) in the proton-conducting O4-water chain was observed in the second flash-induced (2F) XFEL structure (2F-XFEL), which may correspond to S3. By use of a quantum mechanical/molecular mechanical approach, the OH• formation at W539 and the short O4···OW539 distance (<2.3 Å) were reproduced in S2 and S3 with reduced Mn1(III), which lacks the additional sixth water molecule O6. As the O•- formation at O6 and the short O5···O6 distance (1.9 Å) have been reported in another 2F-XFEL structure with reduced Mn4(III), two distinct oxygen-radical conformations exist in the 2F-XFEL crystals.
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Affiliation(s)
- Manoj Mandal
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Keisuke Saito
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Hiroshi Ishikita
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
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25
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Kuroda H, Kawashima K, Ueda K, Ikeda T, Saito K, Ninomiya R, Hida C, Takahashi Y, Ishikita H. Proton transfer pathway from the oxygen-evolving complex in photosystem II substantiated by extensive mutagenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148329. [PMID: 33069681 DOI: 10.1016/j.bbabio.2020.148329] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 10/07/2020] [Accepted: 10/13/2020] [Indexed: 12/11/2022]
Abstract
We report a structure-based biological approach to identify the proton-transfer pathway in photosystem II. First, molecular dynamics (MD) simulations were conducted to analyze the H-bond network that may serve as a Grotthuss-like proton conduit. MD simulations show that D1-Asp61, the H-bond acceptor of H2O at the Mn4CaO5 cluster (W1), forms an H-bond via one water molecule with D1-Glu65 but not with D2-Glu312. Then, D1-Asp61, D1-Glu65, D2-Glu312, and the adjacent residues, D1-Arg334, D2-Glu302, and D2-Glu323, were thoroughly mutated to the other 19 residues, i.e., 114 Chlamydomonas chloroplast mutant cells were generated. Mutation of D1-Asp61 was most crucial. Only the D61E and D61C cells grew photoautotrophically and exhibit O2-evolving activity. Mutations of D2-Glu312 were less crucial to photosynthetic growth than mutations of D1-Glu65. Quantum mechanical/molecular mechanical calculations indicated that in the PSII crystal structure, the proton is predominantly localized at D1-Glu65 along the H-bond with D2-Glu312, i.e., pKa(D1-Glu65) > pKa(D2-Glu312). The potential-energy profile shows that the release of the proton from D1-Glu65 leads to the formation of the two short H-bonds between D1-Asp61 and D1-Glu65, which facilitates downhill proton transfer along the Grotthuss-like proton conduit in the S2 to S3 transition. It seems possible that D1-Glu65 is involved in the dominant pathway that proceeds from W1 via D1-Asp61 toward the thylakoid lumen, whereas D2-Glu312 and D1-Arg334 may be involved in alternative pathways in some mutants.
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Affiliation(s)
- Hiroshi Kuroda
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Keisuke Kawashima
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-8654, Japan
| | - Kazuyo Ueda
- Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Takuya Ikeda
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-8654, Japan
| | - Keisuke Saito
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-8654, Japan; Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Ryo Ninomiya
- Department of Biology, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Chisato Hida
- Department of Biology, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Yuichiro Takahashi
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
| | - Hiroshi Ishikita
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113-8654, Japan; Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
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26
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Saito K, Mandal M, Ishikita H. Energetics of Ionized Water Molecules in the H-Bond Network near the Ca2+ and Cl– Binding Sites in Photosystem II. Biochemistry 2020; 59:3216-3224. [DOI: 10.1021/acs.biochem.0c00177] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Keisuke Saito
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Manoj Mandal
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Hiroshi Ishikita
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
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27
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Acquirement of water-splitting ability and alteration of the charge-separation mechanism in photosynthetic reaction centers. Proc Natl Acad Sci U S A 2020; 117:16373-16382. [PMID: 32601233 PMCID: PMC7368266 DOI: 10.1073/pnas.2000895117] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
In photosynthetic reaction centers from purple bacteria (PbRC) and the water-oxidizing enzyme, photosystem II (PSII), charge separation occurs along one of the two symmetrical electron-transfer branches. Here we report the microscopic origin of the unidirectional charge separation, fully considering electron-hole interaction, electronic coupling of the pigments, and electrostatic interaction with the polarizable entire protein environments. The electronic coupling between the pair of bacteriochlorophylls is large in PbRC, forming a delocalized excited state with the lowest excitation energy (i.e., the special pair). The charge-separated state in the active branch is stabilized by uncharged polar residues in the transmembrane region and charged residues on the cytochrome c 2 binding surface. In contrast, the accessory chlorophyll in the D1 protein (ChlD1) has the lowest excitation energy in PSII. The charge-separated state involves ChlD1 •+ and is stabilized predominantly by charged residues near the Mn4CaO5 cluster and the proceeding proton-transfer pathway. It seems likely that the acquirement of water-splitting ability makes ChlD1 the initial electron donor in PSII.
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Cox N, Pantazis DA, Lubitz W. Current Understanding of the Mechanism of Water Oxidation in Photosystem II and Its Relation to XFEL Data. Annu Rev Biochem 2020; 89:795-820. [DOI: 10.1146/annurev-biochem-011520-104801] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The investigation of water oxidation in photosynthesis has remained a central topic in biochemical research for the last few decades due to the importance of this catalytic process for technological applications. Significant progress has been made following the 2011 report of a high-resolution X-ray crystallographic structure resolving the site of catalysis, a protein-bound Mn4CaOxcomplex, which passes through ≥5 intermediate states in the water-splitting cycle. Spectroscopic techniques complemented by quantum chemical calculations aided in understanding the electronic structure of the cofactor in all (detectable) states of the enzymatic process. Together with isotope labeling, these techniques also revealed the binding of the two substrate water molecules to the cluster. These results are described in the context of recent progress using X-ray crystallography with free-electron lasers on these intermediates. The data are instrumental for developing a model for the biological water oxidation cycle.
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Affiliation(s)
- Nicholas Cox
- Research School of Chemistry, The Australian National University, Canberra ACT 2601, Australia
| | | | - Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion, 45470 Mülheim an der Ruhr, Germany
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29
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Water-oxidizing complex in Photosystem II: Its structure and relation to manganese-oxide based catalysts. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213183] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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30
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Shimada Y, Kitajima-Ihara T, Nagao R, Noguchi T. Role of the O4 Channel in Photosynthetic Water Oxidation as Revealed by Fourier Transform Infrared Difference and Time-Resolved Infrared Analysis of the D1-S169A Mutant. J Phys Chem B 2020; 124:1470-1480. [DOI: 10.1021/acs.jpcb.9b11946] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Yuichiro Shimada
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Tomomi Kitajima-Ihara
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Ryo Nagao
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Takumi Noguchi
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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31
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Mandal M, Kawashima K, Saito K, Ishikita H. Redox Potential of the Oxygen-Evolving Complex in the Electron Transfer Cascade of Photosystem II. J Phys Chem Lett 2020; 11:249-255. [PMID: 31729876 DOI: 10.1021/acs.jpclett.9b02831] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In photosystem II (PSII), water oxidation occurs in the Mn4CaO5 cluster with the release of electrons via the redox-active tyrosine (TyrZ) to the reaction-center chlorophylls (PD1/PD2). Using a quantum mechanical/molecular mechanical approach, we report the redox potentials (Em) of these cofactors in the PSII protein environment. The Em values suggest that the Mn4CaO5 cluster, TyrZ, and PD1/PD2 form a downhill electron transfer pathway. Em for the first oxidation step, Em(S0/S1), is uniquely low (730 mV) and is ∼100 mV lower than that for the second oxidation step, Em(S1/S2) (830 mV) only when the O4 site of the Mn4CaO5 cluster is protonated in S0. The O4-water chain, which directly forms a low-barrier H-bond with the Mn4CaO5 cluster and mediates proton-coupled electron transfer in the S0 to S1 transition, explains why the second lowest oxidation state, S1, is the most stable and S0 is converted to S1 even in the dark.
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Affiliation(s)
- Manoj Mandal
- Research Center for Advanced Science and Technology , The University of Tokyo , 4-6-1 Komaba , Meguro-ku, Tokyo 153-8904 , Japan
| | - Keisuke Kawashima
- Department of Applied Chemistry , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-8654 , Japan
| | - Keisuke Saito
- Research Center for Advanced Science and Technology , The University of Tokyo , 4-6-1 Komaba , Meguro-ku, Tokyo 153-8904 , Japan
- Department of Applied Chemistry , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-8654 , Japan
| | - Hiroshi Ishikita
- Research Center for Advanced Science and Technology , The University of Tokyo , 4-6-1 Komaba , Meguro-ku, Tokyo 153-8904 , Japan
- Department of Applied Chemistry , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-8654 , Japan
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32
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Yamamoto M, Nakamura S, Noguchi T. Protonation structure of the photosynthetic water oxidizing complex in the S0 state as revealed by normal mode analysis using quantum mechanics/molecular mechanics calculations. Phys Chem Chem Phys 2020; 22:24213-24225. [DOI: 10.1039/d0cp04079g] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protonation structure of the first intermediate of the water oxidizing complex was determined by QM/MM calculations of molecular vibrations.
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Affiliation(s)
- Masao Yamamoto
- Division of Material Science
- Graduate School of Science
- Nagoya University
- Nagoya
- Japan
| | - Shin Nakamura
- Division of Material Science
- Graduate School of Science
- Nagoya University
- Nagoya
- Japan
| | - Takumi Noguchi
- Division of Material Science
- Graduate School of Science
- Nagoya University
- Nagoya
- Japan
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33
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Photosystem II oxygen-evolving complex photoassembly displays an inverse H/D solvent isotope effect under chloride-limiting conditions. Proc Natl Acad Sci U S A 2019; 116:18917-18922. [PMID: 31484762 PMCID: PMC6754581 DOI: 10.1073/pnas.1910231116] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Metal clusters play important roles in a wide variety of proteins. In cyanobacteria, algae, and plants, photosystem II uses light energy to oxidize water and release O2 at an active site that contains 1 calcium and 4 manganese atoms. This cluster must be built within the protein environment through a process known as photoassembly. Through experiments and simulations, we found that the efficiency of photoassembly was highly dependent on protons and chloride. Surprisingly, when the solvent was switched from H2O to deuterated water, D2O, the yield of photoassembly was higher. These results provide insights into the stepwise mechanism of photoassembly that can inform synthesis and repair strategies being developed for artificial photosynthesis technologies. Photosystem II (PSII) performs the solar-driven oxidation of water used to fuel oxygenic photosynthesis. The active site of water oxidation is the oxygen-evolving complex (OEC), a Mn4CaO5 cluster. PSII requires degradation of key subunits and reassembly of the OEC as frequently as every 20 to 40 min. The metals for the OEC are assembled within the PSII protein environment via a series of binding events and photochemically induced oxidation events, but the full mechanism is unknown. A role of proton release in this mechanism is suggested here by the observation that the yield of in vitro OEC photoassembly is higher in deuterated water, D2O, compared with H2O when chloride is limiting. In kinetic studies, OEC photoassembly shows a significant lag phase in H2O at limiting chloride concentrations with an apparent H/D solvent isotope effect of 0.14 ± 0.05. The growth phase of OEC photoassembly shows an H/D solvent isotope effect of 1.5 ± 0.2. We analyzed the protonation states of the OEC protein environment using classical Multiconformer Continuum Electrostatics. Combining experiments and simulations leads to a model in which protons are lost from amino acid that will serve as OEC ligands as metals are bound. Chloride and D2O increase the proton affinities of key amino acid residues. These residues tune the binding affinity of Mn2+/3+ and facilitate the deprotonation of water to form a proposed μ-hydroxo bridged Mn2+Mn3+ intermediate.
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34
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Kaur D, Szejgis W, Mao J, Amin M, Reiss KM, Askerka M, Cai X, Khaniya U, Zhang Y, Brudvig GW, Batista VS, Gunner MR. Relative stability of the S 2 isomers of the oxygen evolving complex of photosystem II. PHOTOSYNTHESIS RESEARCH 2019; 141:331-341. [PMID: 30941614 DOI: 10.1007/s11120-019-00637-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 03/15/2019] [Indexed: 06/09/2023]
Abstract
The oxidation of water to O2 is catalyzed by the Oxygen Evolving Complex (OEC), a Mn4CaO5 complex in Photosystem II (PSII). The OEC is sequentially oxidized from state S0 to S4. The S2 state, (MnIII)(MnIV)3, coexists in two redox isomers: S2,g=2, where Mn4 is MnIV and S2,g=4.1, where Mn1 is MnIV. Mn4 has two terminal water ligands, whose proton affinity is affected by the Mn oxidation state. The relative energy of the two S2 redox isomers and the protonation state of the terminal water ligands are analyzed using classical multi-conformer continuum electrostatics (MCCE). The Monte Carlo simulations are done on QM/MM optimized S1 and S2 structures docked back into the complete PSII, keeping the protonation state of the protein at equilibrium with the OEC redox and protonation states. Wild-type PSII, chloride-depleted PSII, PSII in the presence of oxidized YZ/protonated D1-H190, and the PSII mutants D2-K317A, D1-D61A, and D1-S169A are studied at pH 6. The wild-type PSII at pH 8 is also described. In qualitative agreement with experiment, in wild-type PSII, the S2,g=2 redox isomer is the lower energy state; while chloride depletion or pH 8 stabilizes the S2,g=4.1 state and the mutants D2-K317A, D1-D61A, and D1-S169A favor the S2,g=2 state. The protonation states of D1-E329, D1-E65, D1-H337, D1-D61, and the terminal waters on Mn4 (W1 and W2) are affected by the OEC oxidation state. The terminal W2 on Mn4 is a mixture of water and hydroxyl in the S2,g=2 state, indicating the two water protonation states have similar energy, while it remains neutral in the S1 and S2,g=4.1 states. In wild-type PSII, advancement to S2 leads to negligible proton loss and so there is an accumulation of positive charge. In the analyzed mutations and Cl- depleted PSII, additional deprotonation is found upon formation of S2 state.
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Affiliation(s)
- Divya Kaur
- Department of Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
- Department of Physics, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Witold Szejgis
- Department of Physics, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Junjun Mao
- Department of Physics, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Muhamed Amin
- University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Krystle M Reiss
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Mikhail Askerka
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Xiuhong Cai
- Department of Physics, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
- Department of Physics, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Umesh Khaniya
- Department of Physics, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
- Department of Physics, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Yingying Zhang
- Department of Physics, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA
- Department of Physics, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Gary W Brudvig
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - M R Gunner
- Department of Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
- Department of Physics, City College of New York, 160 Convent Avenue, New York, NY, 10031, USA.
- Department of Physics, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
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35
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Five-coordinate Mn IV intermediate in the activation of nature's water splitting cofactor. Proc Natl Acad Sci U S A 2019; 116:16841-16846. [PMID: 31391299 DOI: 10.1073/pnas.1817526116] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nature's water splitting cofactor passes through a series of catalytic intermediates (S0-S4) before O-O bond formation and O2 release. In the second last transition (S2 to S3) cofactor oxidation is coupled to water molecule binding to Mn1. It is this activated, water-enriched all MnIV form of the cofactor that goes on to form the O-O bond, after the next light-induced oxidation to S4 How cofactor activation proceeds remains an open question. Here, we report a so far not described intermediate (S3') in which cofactor oxidation has occurred without water insertion. This intermediate can be trapped in a significant fraction of centers (>50%) in (i) chemical-modified cofactors in which Ca2+ is exchanged with Sr2+; the Mn4O5Sr cofactor remains active, but the S2-S3 and S3-S0 transitions are slower than for the Mn4O5Ca cofactor; and (ii) upon addition of 3% vol/vol methanol; methanol is thought to act as a substrate water analog. The S3' electron paramagnetic resonance (EPR) signal is significantly broader than the untreated S3 signal (2.5 T vs. 1.5 T), indicating the cofactor still contains a 5-coordinate Mn ion, as seen in the preceding S2 state. Magnetic double resonance data extend these findings revealing the electronic connectivity of the S3' cofactor is similar to the high spin form of the preceding S2 state, which contains a cuboidal Mn3O4Ca unit tethered to an external, 5-coordinate Mn ion (Mn4). These results demonstrate that cofactor oxidation regulates water molecule insertion via binding to Mn4. The interaction of ammonia with the cofactor is also discussed.
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36
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Terentyev VV, Shukshina AK, Shitov AV. Carbonic anhydrase CAH3 supports the activity of photosystem II under increased pH. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:582-590. [DOI: 10.1016/j.bbabio.2019.06.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/05/2019] [Accepted: 06/15/2019] [Indexed: 11/24/2022]
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37
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Brahmachari U, Gonthier JF, Sherrill CD, Barry BA. Water Bridges Conduct Sequential Proton Transfer in Photosynthetic Oxygen Evolution. J Phys Chem B 2019; 123:4487-4496. [DOI: 10.1021/acs.jpcb.9b01523] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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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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Abstract
The influence of the environment on the functionality of the oxygen-evolving complex (OEC) of photosystem II has long been a subject of great interest. In particular, various water channels, which could serve as pathways for substrate water diffusion, or proton translocation, are thought to be critical to catalytic performance of the OEC. Here, we address the dynamical nature of hydrogen bonding along the water channels by performing molecular dynamics (MD) simulations of the OEC and its surrounding protein environment in the S1 and S2 states. Through the eigenvector centrality (EC) analysis, we are able to determine the characteristics of the water network and assign potential functions to the major channels, namely that the narrow and broad channels are likely candidates for proton/water transport, while the large channel may serve as a path for larger ions such as chloride and manganese thought to be essential during PSII assembly.
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Abstract
Photosystem II (PSII) uses water as the terminal electron donor, producing oxygen in the Mn4CaO5 oxygen evolving complex (OEC), while cytochrome c oxidase (CcO) reduces O2 to water in its heme–Cu binuclear center (BNC). Each protein is oriented in the membrane to add to the proton gradient. The OEC, which releases protons, is located near the P-side (positive, at low-pH) of the membrane. In contrast, the BNC is in the middle of CcO, so the protons needed for O2 reduction must be transferred from the N-side (negative, at high pH). In addition, CcO pumps protons from N- to P-side, coupled to the O2 reduction chemistry, to store additional energy. Thus, proton transfers are directly coupled to the OEC and BNC redox chemistry, as well as needed for CcO proton pumping. The simulations that study the changes in proton affinity of the redox active sites and the surrounding protein at different states of the reaction cycle, as well as the changes in hydration that modulate proton transfer paths, are described.
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Affiliation(s)
- Dimitrios A. Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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42
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Yata H, Noguchi T. Mechanism of Methanol Inhibition of Photosynthetic Water Oxidation As Studied by Fourier Transform Infrared Difference and Time-Resolved Infrared Spectroscopies. Biochemistry 2018; 57:4803-4815. [DOI: 10.1021/acs.biochem.8b00596] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Haruna Yata
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Takumi Noguchi
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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43
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Brahmachari U, Guo Z, Konecny SE, Obi ENC, Barry BA. Engineering Proton Transfer in Photosynthetic Oxygen Evolution: Chloride, Nitrate, and Trehalose Reorganize a Hydrogen-Bonding Network. J Phys Chem B 2018; 122:6702-6711. [DOI: 10.1021/acs.jpcb.8b02856] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Udita Brahmachari
- Department of Chemistry and Biochemistry, and Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Zhanjun Guo
- Department of Chemistry and Biochemistry, and Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Sara E. Konecny
- Department of Chemistry and Biochemistry, and Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Emmanuela N. C. Obi
- Department of Chemistry and Biochemistry, and Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Bridgette A. Barry
- Department of Chemistry and Biochemistry, and Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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44
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Brahmachari U, Gonthier JF, Sherrill CD, Barry BA. Chloride Maintains a Protonated Internal Water Network in the Photosynthetic Oxygen Evolving Complex. J Phys Chem B 2017; 121:10327-10337. [DOI: 10.1021/acs.jpcb.7b08358] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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45
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Nagao R, Ueoka-Nakanishi H, Noguchi T. D1-Asn-298 in photosystem II is involved in a hydrogen-bond network near the redox-active tyrosine Y Z for proton exit during water oxidation. J Biol Chem 2017; 292:20046-20057. [PMID: 29046348 DOI: 10.1074/jbc.m117.815183] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/04/2017] [Indexed: 01/19/2023] Open
Abstract
In photosynthetic water oxidation, two water molecules are converted into one oxygen molecule and four protons at the Mn4CaO5 cluster in photosystem II (PSII) via the S-state cycle. Efficient proton exit from the catalytic site to the lumen is essential for this process. However, the exit pathways of individual protons through the PSII proteins remain to be identified. In this study, we examined the involvement of a hydrogen-bond network near the redox-active tyrosine YZ in proton transfer during the S-state cycle. We focused on spectroscopic analyses of a site-directed variant of D1-Asn-298, a residue involved in a hydrogen-bond network near YZ We found that the D1-N298A mutant of Synechocystis sp. PCC 6803 exhibits an O2 evolution activity of ∼10% of the wild-type. D1-N298A and the wild-type D1 had very similar features of thermoluminescence glow curves and of an FTIR difference spectrum upon YZ oxidation, suggesting that the hydrogen-bonded structure of YZ and electron transfer from the Mn4CaO5 cluster to YZ were little affected by substitution. In the D1-N298A mutant, however, the flash-number dependence of delayed luminescence showed a monotonic increase without oscillation, and FTIR difference spectra of the S-state cycle indicated partial and significant inhibition of the S2 → S3 and S3 → S0 transitions, respectively. These results suggest that the D1-N298A substitution inhibits the proton transfer processes in the S2 → S3 and S3 → S0 transitions. This in turn indicates that the hydrogen-bond network near YZ can be functional as a proton transfer pathway during photosynthetic water oxidation.
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Affiliation(s)
- Ryo Nagao
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
| | - Hanayo Ueoka-Nakanishi
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Takumi Noguchi
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
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46
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Narzi D, Coccia E, Manzoli M, Guidoni L. Impact of molecular flexibility on the site energy shift of chlorophylls in Photosystem II. Biophys Chem 2017; 229:93-98. [DOI: 10.1016/j.bpc.2017.06.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/26/2017] [Accepted: 06/26/2017] [Indexed: 01/31/2023]
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47
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Baranov S, Haddy A. An enzyme kinetics study of the pH dependence of chloride activation of oxygen evolution in photosystem II. PHOTOSYNTHESIS RESEARCH 2017; 131:317-332. [PMID: 27896527 DOI: 10.1007/s11120-016-0325-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 11/16/2016] [Indexed: 06/06/2023]
Abstract
Oxygen evolution by photosystem II (PSII) involves activation by Cl- ion, which is regulated by extrinsic subunits PsbQ and PsbP. In this study, the kinetics of chloride activation of oxygen evolution was studied in preparations of PSII depleted of the PsbQ and PsbP subunits (NaCl-washed and Na2SO4/pH 7.5-treated) over a pH range from 5.3 to 8.0. At low pH, activation by chloride was followed by inhibition at chloride concentrations >100 mM, whereas at high pH activation continued as the chloride concentration increased above 100 mM. Both activation and inhibition were more pronounced at lower pH, indicating that Cl- binding depended on protonation events in each case. The simplest kinetic model that could account for the complete data set included binding of Cl- at two sites, one for activation and one for inhibition, and four protonation steps. The intrinsic (pH-independent) dissociation constant for Cl- activation, K S, was found to be 0.9 ± 0.2 mM for both preparations, and three of the four pK as were determined, with the fourth falling below the pH range studied. The intrinsic inhibition constant, K I, was found to be 64 ± 2 and 103 ± 7 mM for the NaCl-washed and Na2SO4/pH7.5-treated preparations, respectively, and is considered in terms of the conditions likely to be present in the thylakoid lumen. This enzyme kinetics analysis provides a more complete characterization of chloride and pH dependence of O2 evolution activity than has been previously presented.
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Affiliation(s)
- Sergei Baranov
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, 27402, USA
| | - Alice Haddy
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, 27402, USA.
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48
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Raven JA. Chloride: essential micronutrient and multifunctional beneficial ion. JOURNAL OF EXPERIMENTAL BOTANY 2017; 38:359-367. [PMID: 28040799 DOI: 10.1093/jxb/erw421] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cl− is an essential micronutrient for oxygenic photolithotrophs. About half of global primary productivity is carried out by oxygenic photolithotrophs exposed to saline waters with Cl− concentrations orders of magnitude higher than that needed to satisfy the micronutrient requirement. The other half of primary productivity involves terrestrial and freshwater glycophytes sometimes in environments containing significantly more Cl− than is needed for the micronutrient requirement, but less than the toxic Cl– concentration for glycophytes. Intracellular Cl− acts in regulation of cell turgor and volume, including that of stomatal and pulvinar nastic movements, is a major ion in streptophyte and ulvophycean action potentials, and is involved in ion currents flowing around apices of pollen tubes and Acetabularia cells. More work is needed on the essentiality of Cl− in these processes, as well as the recent finding that Cl− at 1–5 mol m−3 increases water use efficiency of growth and leaf area in Nicotiana tabacum.
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Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, UK
- School of Plant Biology, University of Western Australia MO84, Stirling Highway. Crawley, WA, Australia
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49
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Mandal M, Askerka M, Banerjee G, Amin M, Brudvig GW, Batista VS, Gunner MR. Characterization of ammonia binding to the second coordination shell of the oxygen-evolving complex of photosystem II. Dalton Trans 2017; 46:16089-16095. [DOI: 10.1039/c7dt03901h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The second-shell ammonia binding sites near the oxygen-evolving complex are characterized by Continuum Electrostatic/Monte Carlo (MCCE), QM/MM and DFT calculations and experimental measurements.
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Affiliation(s)
- Manoj Mandal
- Department of Physics
- City College of New York
- C.U.N.Y. New York 10031
- USA
| | | | | | - Muhammed Amin
- Center for Free-Electron Laser Science (CFEL)
- Deutsches Elektronen-Synchrotron DESY
- 22607 Hamburg
- Germany
| | | | | | - M. R. Gunner
- Department of Physics
- City College of New York
- C.U.N.Y. New York 10031
- USA
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50
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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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