1
|
Najafpour MM, Renger G, Hołyńska M, Moghaddam AN, Aro EM, Carpentier R, Nishihara H, Eaton-Rye JJ, Shen JR, Allakhverdiev SI. Manganese Compounds as Water-Oxidizing Catalysts: From the Natural Water-Oxidizing Complex to Nanosized Manganese Oxide Structures. Chem Rev 2016; 116:2886-936. [PMID: 26812090 DOI: 10.1021/acs.chemrev.5b00340] [Citation(s) in RCA: 332] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
All cyanobacteria, algae, and plants use a similar water-oxidizing catalyst for water oxidation. This catalyst is housed in Photosystem II, a membrane-protein complex that functions as a light-driven water oxidase in oxygenic photosynthesis. Water oxidation is also an important reaction in artificial photosynthesis because it has the potential to provide cheap electrons from water for hydrogen production or for the reduction of carbon dioxide on an industrial scale. The water-oxidizing complex of Photosystem II is a Mn-Ca cluster that oxidizes water with a low overpotential and high turnover frequency number of up to 25-90 molecules of O2 released per second. In this Review, we discuss the atomic structure of the Mn-Ca cluster of the Photosystem II water-oxidizing complex from the viewpoint that the underlying mechanism can be informative when designing artificial water-oxidizing catalysts. This is followed by consideration of functional Mn-based model complexes for water oxidation and the issue of Mn complexes decomposing to Mn oxide. We then provide a detailed assessment of the chemistry of Mn oxides by considering how their bulk and nanoscale properties contribute to their effectiveness as water-oxidizing catalysts.
Collapse
Affiliation(s)
| | - Gernot Renger
- Institute of Chemistry, Max-Volmer-Laboratory of Biophysical Chemistry, Technical University Berlin , Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Małgorzata Hołyńska
- Fachbereich Chemie und Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg , Hans-Meerwein-Straße, D-35032 Marburg, Germany
| | | | - Eva-Mari Aro
- Department of Biochemistry and Food Chemistry, University of Turku , 20014 Turku, Finland
| | - Robert Carpentier
- Groupe de Recherche en Biologie Végétale (GRBV), Université du Québec à Trois-Rivières , C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada
| | - Hiroshi Nishihara
- Department of Chemistry, School of Science, The University of Tokyo , 7-3-1, Hongo, Bunkyo-Ku, Tokyo 113-0033, Japan
| | - Julian J Eaton-Rye
- Department of Biochemistry, University of Otago , P.O. Box 56, Dunedin 9054, New Zealand
| | - Jian-Ren Shen
- Photosynthesis Research Center, Graduate School of Natural Science and Technology, Faculty of Science, Okayama University , Okayama 700-8530, Japan.,Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences , Beijing 100093, China
| | - Suleyman I Allakhverdiev
- Controlled Photobiosynthesis Laboratory, Institute of Plant Physiology, Russian Academy of Sciences , Botanicheskaya Street 35, Moscow 127276, Russia.,Institute of Basic Biological Problems, Russian Academy of Sciences , Pushchino, Moscow Region 142290, Russia.,Department of Plant Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University , Leninskie Gory 1-12, Moscow 119991, Russia
| |
Collapse
|
2
|
Han G, Huang Y, Koua FHM, Shen JR, Westlund PO, Messinger J. Hydration of the oxygen-evolving complex of photosystem II probed in the dark-stable S1 state using proton NMR dispersion profiles. Phys Chem Chem Phys 2014; 16:11924-35. [DOI: 10.1039/c3cp55232b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
3
|
Linke K, Ho FM. Water in Photosystem II: Structural, functional and mechanistic considerations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:14-32. [DOI: 10.1016/j.bbabio.2013.08.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/08/2013] [Accepted: 08/13/2013] [Indexed: 12/30/2022]
|
4
|
Vassiliev S, Zaraiskaya T, Bruce D. Molecular dynamics simulations reveal highly permeable oxygen exit channels shared with water uptake channels in photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:1148-55. [PMID: 23816955 DOI: 10.1016/j.bbabio.2013.06.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 06/14/2013] [Accepted: 06/18/2013] [Indexed: 11/28/2022]
Abstract
Photosystem II (PSII) catalyzes the oxidation of water in the conversion of light energy into chemical energy in photosynthesis. Water delivery and oxygen removal from the oxygen evolving complex (OEC), buried deep within PSII, are critical requirements to facilitate the reaction and minimize reactive oxygen damage. It has often been assumed that water and oxygen travel through separate channels within PSII, as demonstrated in cytochrome c oxidase. This study describes all-atom molecular dynamics simulations of PSII designed to investigate channels by fully characterizing the distribution and permeation of both water and oxygen. Interestingly, most channels found in PSII were permeable to both oxygen and water, however individual channels exhibited different energetic barriers for the two solutes. Several routes for oxygen diffusion within PSII with low energy permeation barriers were found, ensuring its fast removal from the OEC. In contrast, all routes for water showed significant energy barriers, corresponding to a much slower permeation rate for water through PSII. Two major factors were responsible for this selectivity: (1) hydrogen bonds between water and channel amino acids, and (2) steric restraints. Our results reveal the presence of a shared network of channels in PSII optimized to both facilitate the quick removal of oxygen and effectively restrict the water supply to the OEC to help stabilize and protect it from small water soluble inhibitors.
Collapse
Affiliation(s)
- Serguei Vassiliev
- Department of Biology, Brock University, 500 Glenridge Ave, St. Catharines L2S 3A1, Canada.
| | | | | |
Collapse
|
5
|
Vassiliev S, Zaraiskaya T, Bruce D. Exploring the energetics of water permeation in photosystem II by multiple steered molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1671-8. [DOI: 10.1016/j.bbabio.2012.05.016] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/28/2012] [Accepted: 05/30/2012] [Indexed: 11/29/2022]
|
6
|
Nishiyama Y, Allakhverdiev SI, Murata N. Protein synthesis is the primary target of reactive oxygen species in the photoinhibition of photosystem II. PHYSIOLOGIA PLANTARUM 2011; 142:35-46. [PMID: 21320129 DOI: 10.1111/j.1399-3054.2011.01457.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Photoinhibition of photosystem II (PSII) occurs when the rate of photodamage to PSII exceeds the rate of the repair of photodamaged PSII. Recent examination of photoinhibition by separate determinations of photodamage and repair has revealed that the rate of photodamage to PSII is directly proportional to the intensity of incident light and that the repair of PSII is particularly sensitive to the inactivation by reactive oxygen species (ROS). The ROS-induced inactivation of repair is attributable to the suppression of the synthesis de novo of proteins, such as the D1 protein, that are required for the repair of PSII at the level of translational elongation. Furthermore, molecular analysis has revealed that the ROS-induced suppression of protein synthesis is associated with the specific inactivation of elongation factor G via the formation of an intramolecular disulfide bond. Impairment of various mechanisms that protect PSII against photoinhibition, including photorespiration, thermal dissipation of excitation energy, and the cyclic transport of electrons, decreases the rate of repair of PSII via the suppression of protein synthesis. In this review, we present a newly established model of the mechanism and the physiological significance of repair in the regulation of the photoinhibition of PSII.
Collapse
Affiliation(s)
- Yoshitaka Nishiyama
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering and Institute for Environmental Science and Technology, Saitama University, Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
| | | | | |
Collapse
|
7
|
Ho FM. Structural and mechanistic investigations of photosystem II through computational methods. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:106-20. [PMID: 21565158 DOI: 10.1016/j.bbabio.2011.04.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/22/2011] [Accepted: 04/02/2011] [Indexed: 11/17/2022]
Abstract
The advent of oxygenic photosynthesis through water oxidation by photosystem II (PSII) transformed the planet, ultimately allowing the evolution of aerobic respiration and an explosion of ecological diversity. The importance of this enzyme to life on Earth has ironically been paralleled by the elusiveness of a detailed understanding of its precise catalytic mechanism. Computational investigations have in recent years provided more and more insights into the structural and mechanistic details that underlie the workings of PSII. This review will present an overview of some of these studies, focusing on those that have aimed at elucidating the mechanism of water oxidation at the CaMn₄ cluster in PSII, and those exploring the features of the structure and dynamics of this enzyme that enable it to catalyse this energetically demanding reaction. This article is part of a Special Issue entitled: Photosystem II.
Collapse
Affiliation(s)
- Felix M Ho
- Deparment of Photochemistry and Molecular Sciences, Angström Laboratory, Uppsala University, Sweden.
| |
Collapse
|
8
|
Lautier T, Ezanno P, Baffert C, Fourmond V, Cournac L, Fontecilla-Camps JC, Soucaille P, Bertrand P, Meynial-Salles I, Léger C. The quest for a functional substrate access tunnel in FeFe hydrogenase. Faraday Discuss 2011; 148:385-407; discussion 421-41. [DOI: 10.1039/c004099c] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
9
|
Williamson A, Conlan B, Hillier W, Wydrzynski T. The evolution of Photosystem II: insights into the past and future. PHOTOSYNTHESIS RESEARCH 2011; 107:71-86. [PMID: 20512415 DOI: 10.1007/s11120-010-9559-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 05/07/2010] [Indexed: 05/29/2023]
Abstract
This article attempts to address the molecular origin of Photosystem II (PSII), the central component in oxygenic photosynthesis. It discusses the possible evolution of the relevant cofactors needed for splitting water into molecular O2 with respect to the following functional domains in PSII: the reaction center (RC), the oxygen evolving complex (OEC), and the manganese stabilizing protein (MSP). Possible ancestral sources of the relevant cofactors are considered, as are scenarios of how these components may have been brought together to produce the intermediate steps in the evolution of PSII. Most importantly, the driving forces that maintained these intermediates for continued adaptation are considered. We then apply our understanding of the evolution of PSII to the bioengineering of a water oxidizing catalyst for utilization of solar energy.
Collapse
Affiliation(s)
- Adele Williamson
- Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra, ACT, 0200, Australia
| | | | | | | |
Collapse
|
10
|
Service RJ, Yano J, McConnell I, Hwang HJ, Niks D, Hille R, Wydrzynski T, Burnap RL, Hillier W, Debus RJ. Participation of glutamate-354 of the CP43 polypeptide in the ligation of manganese and the binding of substrate water in photosystem II. Biochemistry 2010; 50:63-81. [PMID: 21114287 DOI: 10.1021/bi1015937] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the current X-ray crystallographic structural models of photosystem II, Glu354 of the CP43 polypeptide is the only amino acid ligand of the oxygen-evolving Mn(4)Ca cluster that is not provided by the D1 polypeptide. To further explore the influence of this structurally unique residue on the properties of the Mn(4)Ca cluster, the CP43-E354Q mutant of the cyanobacterium Synechocystis sp. PCC 6803 was characterized with a variety of biophysical and spectroscopic methods, including polarography, EPR, X-ray absorption, FTIR, and mass spectrometry. The kinetics of oxygen release in the mutant were essentially unchanged from those in wild type. In addition, the oxygen flash yields exhibited normal period four oscillations having normal S state parameters, although the yields were lower, correlating with the mutant's lower steady-state rate (approximately 20% compared to wild type). Experiments conducted with H(2)(18)O showed that the fast and slow phases of substrate water exchange in CP43-E354Q thylakoid membranes were accelerated 8.5- and 1.8-fold, respectively, in the S(3) state compared to wild type. Purified oxygen-evolving CP43-E354Q PSII core complexes exhibited a slightly altered S(1) state Mn-EXAFS spectrum, a slightly altered S(2) state multiline EPR signal, a substantially altered S(2)-minus-S(1) FTIR difference spectrum, and an unusually long lifetime for the S(2) state (>10 h) in a substantial fraction of reaction centers. In contrast, the S(2) state Mn-EXAFS spectrum was nearly indistinguishable from that of wild type. The S(2)-minus-S(1) FTIR difference spectrum showed alterations throughout the amide and carboxylate stretching regions. Global labeling with (15)N and specific labeling with l-[1-(13)C]alanine revealed that the mutation perturbs both amide II and carboxylate stretching modes and shifts the symmetric carboxylate stretching modes of the α-COO(-) group of D1-Ala344 (the C-terminus of the D1 polypeptide) to higher frequencies by 3-4 cm(-1) in both the S(1) and S(2) states. The EPR and FTIR data implied that 76-82% of CP43-E354Q PSII centers can achieve the S(2) state and that most of these can achieve the S(3) state, but no evidence for advancement beyond the S(3) state was observed in the FTIR data, at least not in a majority of PSII centers. Although the X-ray absorption and EPR data showed that the CP43-E354Q mutation only subtly perturbs the structure and spin state of the Mn(4)Ca cluster in the S(2) state, the FTIR and H(2)(18)O exchange data show that the mutation strongly influences other properties of the Mn(4)Ca cluster, altering the response of numerous carboxylate and amide groups to the increased positive charge that develops on the cluster during the S(1) to S(2) transition and weakening the binding of both substrate water molecules (or water-derived ligands), especially the one that exchanges rapidly in the S(3) state. The FTIR data provide evidence that CP43-Glu354 coordinates to the Mn(4)Ca cluster in the S(1) state as a bridging ligand between two metal ions but provide no compelling evidence that this residue changes its coordination mode during the S(1) to S(2) transition. The H(2)(18)O exchange data provide evidence that CP43-Glu354 interacts with the Mn ion that ligates the substrate water molecule (or water-derived ligand) that is in rapid exchange in the S(3) state.
Collapse
Affiliation(s)
- Rachel J Service
- Department of Biochemistry, University of California, Riverside, California 92521, United States
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Service RJ, Hillier W, Debus RJ. Evidence from FTIR difference spectroscopy of an extensive network of hydrogen bonds near the oxygen-evolving Mn(4)Ca cluster of photosystem II involving D1-Glu65, D2-Glu312, and D1-Glu329. Biochemistry 2010; 49:6655-69. [PMID: 20593803 DOI: 10.1021/bi100730d] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Analyses of the refined X-ray crystallographic structures of photosystem II (PSII) at 2.9-3.5 A have revealed the presence of possible channels for the removal of protons from the catalytic Mn(4)Ca cluster during the water-splitting reaction. As an initial attempt to verify these channels experimentally, the presence of a network of hydrogen bonds near the Mn(4)Ca cluster was probed with FTIR difference spectroscopy in a spectral region sensitive to the protonation states of carboxylate residues and, in particular, with a negative band at 1747 cm(-1) that is often observed in the S(2)-minus-S(1) FTIR difference spectrum of PSII from the cyanobacterium Synechocystis sp. PCC 6803. On the basis of its 4 cm(-1) downshift in D(2)O, this band was assigned to the carbonyl stretching vibration (C horizontal lineO) of a protonated carboxylate group whose pK(a) decreases during the S(1) to S(2) transition. The positive charge that forms on the Mn(4)Ca cluster during the S(1) to S(2) transition presumably causes structural perturbations that are transmitted to this carboxylate group via electrostatic interactions and/or an extended network of hydrogen bonds. In an attempt to identify the carboxylate group that gives rise to this band, the FTIR difference spectra of PSII core complexes from the mutants D1-Asp61Ala, D1-Glu65Ala, D1-Glu329Gln, and D2-Glu312Ala were examined. In the X-ray crystallographic models, these are the closest carboxylate residues to the Mn(4)Ca cluster that do not ligate Mn or Ca and all are highly conserved. The 1747 cm(-1) band is present in the S(2)-minus-S(1) FTIR difference spectrum of D1-Asp61Ala but absent from the corresponding spectra of D1-Glu65Ala, D2-Glu312Ala, and D1-Glu329Gln. The band is also sharply diminished in magnitude in the wild type when samples are maintained at a relative humidity of </=85%. It is proposed that D1-Glu65, D2-Glu312, and D1-Glu329 participate in a common network of hydrogen bonds that includes water molecules and the carboxylate group that gives rise to the 1747 cm(-1) band. It is further proposed that the mutation of any of these three residues, or partial dehydration caused by maintaining samples at a relative humidity of <or=85%, disrupts the network sufficiently that the structural perturbations associated with the S(1) to S(2) transition are no longer transmitted to the carboxylate group that gives rise to the 1747 cm(-1) band. Because D1-Glu329 is located approximately 20 A from D1-Glu65 and D2-Glu312, the postulated network of hydrogen bonds must extend for at least 20 A across the lumenal face of the Mn(4)Ca cluster. The D1-Asp61Ala, D1-Glu65Ala, and D2-Glu312Ala mutations also appear to substantially decrease the fraction of PSII reaction centers that undergo the S(3) to S(0) transition in response to a saturating flash. This behavior is consistent with D1-Asp61, D1-Glu65, and D2-Glu312 participating in a dominant proton egress channel that links the Mn(4)Ca cluster with the thylakoid lumen.
Collapse
Affiliation(s)
- Rachel J Service
- Department of Biochemistry, University of California, Riverside, California 92521, USA
| | | | | |
Collapse
|
12
|
Gabdulkhakov A, Guskov A, Broser M, Kern J, Müh F, Saenger W, Zouni A. Probing the Accessibility of the Mn4Ca Cluster in Photosystem II: Channels Calculation, Noble Gas Derivatization, and Cocrystallization with DMSO. Structure 2009; 17:1223-34. [DOI: 10.1016/j.str.2009.07.010] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/16/2009] [Accepted: 07/21/2009] [Indexed: 01/05/2023]
|
13
|
Sicora CI, Ho FM, Salminen T, Styring S, Aro EM. Transcription of a “silent” cyanobacterial psbA gene is induced by microaerobic conditions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:105-12. [DOI: 10.1016/j.bbabio.2008.12.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 12/06/2008] [Accepted: 12/08/2008] [Indexed: 11/15/2022]
|
14
|
McConnell IL. Substrate water binding and oxidation in photosystem II. PHOTOSYNTHESIS RESEARCH 2008; 98:261-276. [PMID: 18766463 DOI: 10.1007/s11120-008-9337-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 07/19/2008] [Indexed: 05/26/2023]
Abstract
This mini review presents a general introduction to photosystem II with an emphasis on the oxygen evolving complex. An attempt is made to summarise what is currently known about substrate interaction in the oxygen evolving complex of photosystem II in terms of the nature of the substrate, the timing and the location of its binding. As the nature of substrate water binding has a direct bearing on the mechanism of O-O bond formation in PSII, a discussion of O-O bond formation follows the summary of current opinion in substrate interaction.
Collapse
Affiliation(s)
- Iain L McConnell
- Research School of Biological Sciences, The Australian National University, 0200 Canberra, ACT, Australia.
| |
Collapse
|
15
|
Renger G, Renger T. Photosystem II: The machinery of photosynthetic water splitting. PHOTOSYNTHESIS RESEARCH 2008; 98:53-80. [PMID: 18830685 DOI: 10.1007/s11120-008-9345-7] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 07/29/2008] [Indexed: 05/26/2023]
Abstract
This review summarizes our current state of knowledge on the structural organization and functional pattern of photosynthetic water splitting in the multimeric Photosystem II (PS II) complex, which acts as a light-driven water: plastoquinone-oxidoreductase. The overall process comprises three types of reaction sequences: (1) photon absorption and excited singlet state trapping by charge separation leading to the ion radical pair [Formula: see text] formation, (2) oxidative water splitting into four protons and molecular dioxygen at the water oxidizing complex (WOC) with P680+* as driving force and tyrosine Y(Z) as intermediary redox carrier, and (3) reduction of plastoquinone to plastoquinol at the special Q(B) binding site with Q(A)-* acting as reductant. Based on recent progress in structure analysis and using new theoretical approaches the mechanism of reaction sequence (1) is discussed with special emphasis on the excited energy transfer pathways and the sequence of charge transfer steps: [Formula: see text] where (1)(RC-PC)* denotes the excited singlet state (1)P680* of the reaction centre pigment complex. The structure of the catalytic Mn(4)O(X)Ca cluster of the WOC and the four step reaction sequence leading to oxidative water splitting are described and problems arising for the electronic configuration, in particular for the nature of redox state S(3), are discussed. The unravelling of the mode of O-O bond formation is of key relevance for understanding the mechanism of the process. This problem is not yet solved. A multistate model is proposed for S(3) and the functional role of proton shifts and hydrogen bond network(s) is emphasized. Analogously, the structure of the Q(B) site for PQ reduction to PQH(2) and the energetic and kinetics of the two step redox reaction sequence are described. Furthermore, the relevance of the protein dynamics and the role of water molecules for its flexibility are briefly outlined. We end this review by presenting future perspectives on the water oxidation process.
Collapse
Affiliation(s)
- Gernot Renger
- Max Volmer Laboratory for Biophysical Chemistry, Berlin Institute of Technology, Berlin, Germany.
| | | |
Collapse
|
16
|
Murray JW, Maghlaoui K, Kargul J, Sugiura M, Barber J. Analysis of xenon binding to photosystem II by X-ray crystallography. PHOTOSYNTHESIS RESEARCH 2008; 98:523-7. [PMID: 18839332 DOI: 10.1007/s11120-008-9366-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Accepted: 09/09/2008] [Indexed: 05/03/2023]
Abstract
In order to investigate oxygen binding and hydrophobic cavities in photosystem II (PSII), we have introduced xenon under pressure into crystals of PSII isolated from Thermosynechococcus elongatus and used X-ray anomalous diffraction analyses to identify the xenon sites in the complex. Under the conditions employed, 25 Xe-binding sites were identified in each monomer of the dimeric PSII complex. The majority of these were distributed within the membrane spanning portion of the complex with no obvious correlation with the previously proposed oxygen channels. One binding site was located close to the haem of cytochrome b559 in a position analogous to a Xe-binding site of myoglobin. The only Xe-binding site not associated with the intrinsic subunits of PSII was within the hydrophobic core of the PsbO protein.
Collapse
Affiliation(s)
- J W Murray
- Division of Molecular Biosciences, Imperial College London, London, UK
| | | | | | | | | |
Collapse
|
17
|
Ho FM. Uncovering channels in photosystem II by computer modelling: current progress, future prospects, and lessons from analogous systems. PHOTOSYNTHESIS RESEARCH 2008; 98:503-522. [PMID: 18798008 DOI: 10.1007/s11120-008-9358-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 08/18/2008] [Indexed: 05/26/2023]
Abstract
Even prior to the publication of the crystal structures for photosystem II (PSII), it had already been suggested that water, O(2) and H(+) channels exist in PSII to achieve directed transport of these molecules, and to avoid undesirable side reactions. Computational efforts to uncover these channels and investigate their properties are still at early stages, and have so far only been based on the static PSII structure. The rationale behind the proposals for such channels and the computer modelling studies thus far are reviewed here. The need to take the dynamic protein into account is then highlighted with reference to the specific issues and techniques applicable to the simulation of each of the three channels. In particular, lessons are drawn from simulation studies on other protein systems containing similar channels.
Collapse
Affiliation(s)
- Felix M Ho
- Department of Photochemistry and Molecular Science, The Angström Laboratory, Uppsala University, Uppsala, Sweden.
| |
Collapse
|
18
|
Takahashi S, Murata N. How do environmental stresses accelerate photoinhibition? TRENDS IN PLANT SCIENCE 2008; 13:178-82. [PMID: 18328775 DOI: 10.1016/j.tplants.2008.01.005] [Citation(s) in RCA: 521] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 01/21/2008] [Accepted: 01/22/2008] [Indexed: 05/18/2023]
Abstract
Environmental stress enhances the extent of photoinhibition, a process that is determined by the balance between the rate of photodamage to photosystem II (PSII) and the rate of its repair. Recent investigations suggest that exposure to environmental stresses, such as salt, cold, moderate heat and oxidative stress, do not affect photodamage but inhibit the repair of PSII through suppression of the synthesis of PSII proteins. In particular, production of D1 protein is downregulated at the translation step by the direct inactivation of the translation machinery and/or by primarily interrupting the fixation of CO2. The latter results in the creation of reactive oxygen species (ROS), which in turn block the synthesis of PSII proteins in chloroplasts.
Collapse
Affiliation(s)
- Shunichi Takahashi
- Molecular Plant Physiology Group and Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 0200, Australia
| | | |
Collapse
|
19
|
Ho FM, Styring S. Access channels and methanol binding site to the CaMn4 cluster in Photosystem II based on solvent accessibility simulations, with implications for substrate water access. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:140-53. [DOI: 10.1016/j.bbabio.2007.08.009] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 08/28/2007] [Accepted: 08/29/2007] [Indexed: 10/22/2022]
|
20
|
Nishiyama Y, Allakhverdiev SI, Murata N. Regulation by Environmental Conditions of the Repair of Photosystem II in Cyanobacteria. PHOTOPROTECTION, PHOTOINHIBITION, GENE REGULATION, AND ENVIRONMENT 2008. [DOI: 10.1007/1-4020-3579-9_13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
21
|
Mamedov F, Gadjieva R, Styring S. Oxygen-induced changes in the redox state of the cytochrome b559 in photosystem II depend on the integrity of the Mn cluster. PHYSIOLOGIA PLANTARUM 2007; 131:41-49. [PMID: 18251923 DOI: 10.1111/j.1399-3054.2007.00938.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The effect of oxygen and anaerobiosis on the redox properties of Cyt b(559) was investigated in PSII preparations from spinach with different degree of disintegration of the donor side. Comparative studies were performed on intact PSII membranes and PSII membranes that were deprived of the 18-kDa peripheral subunit (0.25 NaCl washed), the 18- and 24-kDa peripheral subunits (1 M NaCl washed), the 18-, 24- and 33-kDa peripheral subunits (1.2 M CaCl(2) washed), Cl depleted and after complete depletion of the Mn cluster (Tris washed). In active PSII centers, about 75% of Cyt b(559) was found in the high-potential form and the rest in the intermediate potential form. With decomposition of the donor side, the intermediate potential form started to dominate, reaching more than 90% after Tris treatment. The oxygen-dependent conversion of the intermediate potential form of Cyt b(559) into the low-potential and high-potential forms was only observed after treatments that directly affect the Mn cluster. In PSII membranes, deprived of all three extrinsic subunits (CaCl(2) treatment), 21% of the intermediate potential form was converted into the low-potential form and 14% into the high-potential form by the removal of oxygen. In Tris-washed PSII membranes, completely lacking the Mn cluster, this conversion amounted to 60 and 33%, respectively. In intact PSII membranes, the oxygen-dependent conversion did not occur. The possible physiological role of this oxygen-dependent behavior of the Cyt b(559) redox forms during the assembly/photoactivation cycle of PSII is discussed.
Collapse
Affiliation(s)
- Fikret Mamedov
- Molecular Biomimetics, Department of Photochemistry and Molecular Science, Angström Laboratory, Uppsala University, PO Box 523, 75120 Uppsala, Sweden.
| | | | | |
Collapse
|
22
|
Renger G. Oxidative photosynthetic water splitting: energetics, kinetics and mechanism. PHOTOSYNTHESIS RESEARCH 2007; 92:407-25. [PMID: 17647091 DOI: 10.1007/s11120-007-9185-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Accepted: 04/19/2007] [Indexed: 05/16/2023]
Abstract
This minireview is an attempt to summarize our current knowledge on oxidative water splitting in photosynthesis. Based on the extended Kok model (Kok, Forbush, McGloin (1970) Photochem Photobiol 11:457-476) as a framework, the energetics and kinetics of two different types of reactions comprising the overall process are discussed: (i) P680+* reduction by the redox active tyrosine YZ of polypeptide D1 and (ii) Yz (ox) induced oxidation of the four step sequence in the water oxidizing complex (WOC) leading to the formation of molecular oxygen. The mode of coupling between electron transport (ET) and proton transfer (PT) is of key mechanistic relevance for the redox turnover of YZ and the reactions within the WOC. The peculiar energetics of the oxidation steps in the WOC assure that redox state S1 is thermodynamically most stable. This is a general feature in all oxygen evolving photosynthetic organisms and assumed to be of physiological relevance. The reaction coordinate of oxidative water splitting is discussed on the basis of the available information about the Gibbs energy differences between the individual redox states Si+1 and Si and the data reported for the activation energies of the individual oxidation steps in the WOC. Finally, an attempt is made to cast our current state of knowledge into a mechanism of oxidative water splitting with special emphasis on the formation of the essential O-O bond and on the active role of the protein in tuning the local proton activity that depends on time and redox state Si. The O-O linkage is assumed to take place at the level of a complexed peroxide.
Collapse
Affiliation(s)
- Gernot Renger
- Technische Universität Berlin, Institut für Chemie, Max-Volmer-Laboratorium für Biophysikalische Chemie, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
| |
Collapse
|
23
|
Renger G, Kühn P. Reaction pattern and mechanism of light induced oxidative water splitting in photosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1767:458-71. [PMID: 17428439 DOI: 10.1016/j.bbabio.2006.12.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 12/08/2006] [Accepted: 12/13/2006] [Indexed: 11/18/2022]
Abstract
This mini review is an attempt to briefly summarize our current knowledge on light driven oxidative water splitting in photosynthesis. The reaction leading to molecular oxygen and four protons via photosynthesis comprises thermodynamic and kinetic constraints that require a balanced fine tuning of the reaction coordinates. The mode of coupling between electron (ET) and proton transfer (PT) reactions is shown to be of key mechanistic relevance for the redox turnover of Y(Z) and the reactions within the WOC. The WOC is characterized by peculiar energetics of its oxidation steps in the WOC. In all oxygen evolving photosynthetic organisms the redox state S(1) is thermodynamically most stable and therefore this general feature is assumed to be of physiological relevance. Available information on the Gibbs energy differences between the individual redox states S(i+1) and S(i) and on the activation energies of their oxidative transitions are used to construct a general reaction coordinate of oxidative water splitting in photosystem II (PS II). Finally, an attempt is presented to cast our current state of knowledge into a mechanism of oxidative water splitting with special emphasis on the formation of the essential O-O bond and the active role of the protein environment in tuning the local proton activity that depends on time and redox state S(i). The O-O linkage is assumed to take place within a multistate equilibrium at the redox level of S(3), comprising both redox isomerism and proton tautomerism. It is proposed that one state, S(3)(P), attains an electronic configuration and nuclear geometry that corresponds with a hydrogen bonded peroxide which acts as the entatic state for the generation of complexed molecular oxygen through S(3)(P) oxidation by Y(Z)(ox).
Collapse
Affiliation(s)
- Gernot Renger
- Technische Universität Berlin, Institut für Chemie, Max-Volmer-Laboratorium für Biophysikalische Chemie, Strasse des 17.Juni 135, D-10623 Berlin, Germany.
| | | |
Collapse
|
24
|
Nishiyama Y, Allakhverdiev SI, Murata N. A new paradigm for the action of reactive oxygen species in the photoinhibition of photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:742-9. [PMID: 16784721 DOI: 10.1016/j.bbabio.2006.05.013] [Citation(s) in RCA: 402] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 05/02/2006] [Accepted: 05/04/2006] [Indexed: 11/16/2022]
Abstract
Inhibition of the activity of photosystem II (PSII) under strong light is referred to as photoinhibition. This phenomenon is due to the imbalance between the rate of photodamage to PSII and the rate of the repair of damaged PSII. Photodamage is initiated by the direct effects of light on the oxygen-evolving complex and, thus, photodamage to PSII is unavoidable. Studies of the effects of oxidative stress on photodamage and subsequent repair have revealed that reactive oxygen species (ROS) act primarily by inhibiting the repair of photodamaged PSII and not by damaging PSII directly. Thus, strong light has two distinct effects on PSII; it damages PSII directly and it inhibits the repair of PSII via production of ROS. Investigations of the ROS-induced inhibition of repair have demonstrated that ROS suppress the synthesis de novo of proteins and, in particular, of the D1 protein, that are required for the repair of PSII. Moreover, a primary target for inhibition by ROS appears to be the elongation step of translation. Inhibition of the repair of PSII by ROS is accelerated by the deceleration of the Calvin cycle that occurs when the availability of CO(2) is limited. In this review, we present a new paradigm for the action of ROS in photoinhibition.
Collapse
Affiliation(s)
- Yoshitaka Nishiyama
- Cell-Free Science and Technology Research Center and Satellite Venture Business Laboratory, Ehime University, Bunkyo-cho, Matsuyama, Japan.
| | | | | |
Collapse
|
25
|
Nishiyama Y, Allakhverdiev SI, Murata N. Inhibition of the repair of photosystem II by oxidative stress in cyanobacteria. PHOTOSYNTHESIS RESEARCH 2005; 84:1-7. [PMID: 16049747 DOI: 10.1007/s11120-004-6434-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 11/16/2004] [Indexed: 05/03/2023]
Abstract
The activity of Photosystem II (PS II) is severely restricted by a variety of environmental factors and, under environmental stress, is determined by the balance between the rate of damage to PS II and the rate of the repair of damaged PS II. The effects of oxidative stress on damage and repair can be examined separately, and it appears that, while light can damage PS II directly, oxidative stress acts primarily by inhibiting the repair of PS II. Studies in cyanobacteria have demonstrated that oxidative stress suppresses the de novo synthesis of proteins, in particular, the D1 protein, which is required for the repair of PS II.
Collapse
Affiliation(s)
- Yoshitaka Nishiyama
- Cell-Free Science and Technology Research Center and Satellite Venture Business Laboratory, Ehime University, Matsuyama, 790-8577 Japan.
| | | | | |
Collapse
|
26
|
Loll B, Gerold G, Slowik D, Voelter W, Jung C, Saenger W, Irrgang KD. Thermostability and Ca2+Binding Properties of Wild Type and Heterologously Expressed PsbO Protein from Cyanobacterial Photosystem II†. Biochemistry 2005; 44:4691-8. [PMID: 15779895 DOI: 10.1021/bi047614r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oxygenic photosynthesis takes place in the thylakoid membrane of cyanobacteria, algae, and higher plants. Initially light is absorbed by an oligomeric pigment-protein complex designated as photosystem II (PSII), which catalyzes light-induced water cleavage under release of molecular oxygen for the biosphere on our planet. The membrane-extrinsic manganese stabilizing protein (PsbO) is associated on the lumenal side of the thylakoids close to the redox-active (Mn)(4)Ca cluster at the catalytically active site of PSII. Recombinant PsbO from the thermophilic cyanobacterium Thermosynechococcus elongatus was expressed in Escherichia coli and spectroscopically characterized. The secondary structure of recombinant PsbO (recPsbO) was analyzed in the absence and presence of Ca(2+) using Fourier transform infrared spectroscopy (FTIR) and circular dichroism spectropolarimetry (CD). No significant structural changes could be observed when the PSII subunit was titrated with Ca(2+) in vitro. These findings are compared with data for spinach PsbO. Our results are discussed in the light of the recent 3D-structural analysis of the oxygen-evolving PSII and structural/thermodynamic differences between the two homologous proteins from thermophilic cyanobacteria and plants.
Collapse
Affiliation(s)
- Bernhard Loll
- Department of Chemistry/Crystallography, Free University Berlin, 14195 Berlin, Germany.
| | | | | | | | | | | | | |
Collapse
|
27
|
Ivanov II, Fedorov GE, Gus'kova RA, Ivanov KI, Rubin AB. Permeability of lipid membranes to dioxygen. Biochem Biophys Res Commun 2004; 322:746-50. [PMID: 15336527 DOI: 10.1016/j.bbrc.2004.07.187] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Indexed: 11/20/2022]
Abstract
It is commonly supposed that dioxygen (O(2)) transport through biomembranes is ensured by the high permeability of a lipid bilayer in which O(2) diffusion mobility is close to that in water. However, the fact that microviscosity of lipid membranes is higher than that of water by two to three orders of magnitude speaks against this concept. Therefore, in this work we investigated the influence of surface lipid monolayers on oxygen diffusion flow directed from air to aqueous phase. We show that for lipid monolayers, the O(2) permeability coefficients are within the range of 10(-4) to 10(-5)m/s. These values are three to four orders of magnitude lower than has been previously thought, indicating that lipid membranes constitute a considerable barrier to O(2) diffusion. From this, we suggest that membranes of aerobic organisms contain O(2) channels to ensure the high-volume transmembrane O(2) flows.
Collapse
Affiliation(s)
- Ilya I Ivanov
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia.
| | | | | | | | | |
Collapse
|
28
|
Balsera M, Arellano JB, Pazos F, Devos D, Valencia A, De Las Rivas J. The single tryptophan of the PsbQ protein of photosystem II is at the end of a 4-α-helical bundle domain. ACTA ACUST UNITED AC 2003; 270:3916-27. [PMID: 14511373 DOI: 10.1046/j.1432-1033.2003.03774.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We examined the microenvironment of the single tryptophan and the tyrosine residues of PsbQ, one of the three main extrinsic proteins of green algal and higher plant photosystem II. On the basis of this information and the previous data on secondary structure [Balsera, M., Arellano, J.B., Gutiérrez, J.R., Heredia, P., Revuelta, J.L. & De Las Rivas, J. (2003) Biochemistry42, 1000-1007], we screened structural models derived by combining various threading approaches. Experimental results showed that the tryptophan residue is partially buried in the core of the protein but still in a polar environment, according to the intrinsic fluorescence emission of PsbQ and the fact that fluorescence quenching by iodide was weaker than that by acrylamide. Furthermore, quenching by cesium suggested that a positively charged barrier shields the tryptophan microenvironment. Comparison of the absorption spectra in native and denaturing conditions indicated that one or two out of six tyrosines of PsbQ are buried in the core of the structure. Using threading methods, a 3D structural model was built for the C-terminal domain of the PsbQ protein family (residues 46-149), while the N-terminal domain is predicted to have a flexible structure. The model for the C-terminal domain is based on the 3D structure of cytochrome b562, a mainly alpha-protein with a helical up/down bundle folding. Despite the large sequence differences between the template and PsbQ, the structural and energetic parameters for the explicit model are acceptable, as judged by the corresponding tools. This 3D model is compatible with the experimentally determined environment of the tryptophan residue and with published structural information. The future experimental determination of the 3D structure of the protein will offer a good validation point for our model and the technology used. Until then, the model can provide a starting point for further studies on the function of PsbQ.
Collapse
Affiliation(s)
- Mónica Balsera
- Instituto de Recursos Naturales y Agrobiología (CSIC), Cordel de Merinas, Salamanca, Spain
| | | | | | | | | | | |
Collapse
|
29
|
Balsera M, Arellano JB, Gutiérrez JR, Heredia P, Revuelta JL, De Las Rivas J. Structural analysis of the PsbQ protein of photosystem II by Fourier transform infrared and circular dichroic spectroscopy and by bioinformatic methods. Biochemistry 2003; 42:1000-7. [PMID: 12549920 DOI: 10.1021/bi026575l] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structure of PsbQ, one of the three main extrinsic proteins associated with the oxygen-evolving complex (OEC) of higher plants and green algae, is examined by Fourier transform infrared (FTIR) and circular dichroic (CD) spectroscopy and by computational structural prediction methods. This protein, together with two other lumenally bound extrinsic proteins, PsbO and PsbP, is essential for the stability and full activity of the OEC in plants. The FTIR spectra obtained in both H(2)O and D(2)O suggest a mainly alpha-helix structure on the basis of the relative areas of the constituents of the amide I and I' bands. The FTIR quantitative analyses indicate that PsbQ contains about 53% alpha-helix, 7% turns, 14% nonordered structure, and 24% beta-strand plus other beta-type extended structures. CD analyses indicate that PsbQ is a mainly alpha-helix protein (about 64%), presenting a small percentage assigned to beta-strand ( approximately 7%) and a larger amount assigned to turns and nonregular structures ( approximately 29%). Independent of the spectroscopic analyses, computational methods for protein structure prediction of PsbQ were utilized. First, a multiple alignment of 12 sequences of PsbQ was obtained after an extensive search in the public databases for protein and EST sequences. Based on this alignment, computational prediction of the secondary structure and the solvent accessibility suggest the presence of two different structural domains in PsbQ: a major C-terminal domain containing four alpha-helices and a minor N-terminal domain with a poorly defined secondary structure enriched in proline and glycine residues. The search for PsbQ analogues by fold recognition methods, not based on the secondary structure, also indicates that PsbQ is a four alpha-helix protein, most probably folding as an up-down bundle. The results obtained by both the spectroscopic and computational methods are in agreement, all indicating that PsbQ is mainly an alpha protein, and show the value of using both methodologies for protein structure investigation.
Collapse
Affiliation(s)
- Mónica Balsera
- Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas, Cordel de Merinas 52, Salamanca 37008, Spain
| | | | | | | | | | | |
Collapse
|
30
|
Abstract
In this review we focus on photosynthetic behavior of overwintering evergreens with an emphasis on both the acclimative responses of photosynthesis to cold and the winter behavior of photosynthesis in conifers. Photosynthetic acclimation is discussed in terms of the requirement for a balance between the energy absorbed through largely temperature-insensitive photochemical processes and the energy used for temperature-sensitive biochemical processes and growth. Cold acclimation transforms the xanthophyll-mediated nonphotochemical antenna quenching of absorbed light from a short-term dynamic response to a long-term sustained quenching for the whole winter period. This acclimative response helps protect the evergreen foliage from photooxidative damage during the winter when photosynthesis is restricted or prevented by low temperatures. Although the molecular mechanisms behind the sustained winter excitation quenching are largely unknown, it does involve major alterations in the organization and composition of the photosystem II antenna. In addition, photosystem I may play an important role in overwintering evergreens not only by quenching absorbed light photochemically via its support of cyclic electron transport at low temperatures, but also by nonphotochemical quenching of absorbed light irrespective of temperature. The possible role of photosystem II reaction centers in nonphotochemical quenching of absorbed energy in overwintering evergreens is also discussed. Processes like chlororespiration and cyclic electron transport may also be important for maintaining the functional integrity of the photosynthetic apparatus of overwintering evergreens both during periods of thawing in winter and during recovery from winter stress in spring. We suggest that the photosynthetic acclimation responses of overwintering evergreens represent specific evolutionary adaptations for plant species that invest in the long-term maintenance of leaf structure in cold climatic zones as exemplified by the boreal forests of the Northern Hemisphere.
Collapse
Affiliation(s)
- Gunnar Oquist
- Umeå Plant Science Center (UPSC), Department of Plant Physiology, Umeå University, SE-90187 Umeå, Sweden.
| | | |
Collapse
|
31
|
Anderson JM, Chow WS. Structural and functional dynamics of plant photosystem II. Philos Trans R Soc Lond B Biol Sci 2002; 357:1421-30; discussion 1469-70. [PMID: 12437881 PMCID: PMC1693045 DOI: 10.1098/rstb.2002.1138] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Given the unique problem of the extremely high potential of the oxidant P(+)(680) that is required to oxidize water to oxygen, the photoinactivation of photosystem II in vivo is inevitable, despite many photoprotective strategies. There is, however, a robustness of photosystem II, which depends partly on the highly dynamic compositional and structural heterogeneity of the cycle between functional and non-functional photosystem II complexes in response to light level. This coordinated regulation involves photon usage (energy utilization in photochemistry) and excess energy dissipation as heat, photoprotection by many molecular strategies, photoinactivation followed by photon damage and ultimately the D1 protein dynamics involved in the photosystem II repair cycle. Compelling, though indirect evidence suggests that the radical pair P(+)(680)Pheo(-) in functional PSII should be protected from oxygen. By analogy to the tentative oxygen channel of cytochrome c oxidase, oxygen may be liberated from the two water molecules bound to the catalytic site of the Mn cluster, via a specific pathway to the membrane surface. The function of the proposed oxygen pathway is to prevent O(2) from having direct access to P(+)(680)Pheo(-) and prevent the generation of singlet oxygen via the triplet-P(680) state in functional photosytem IIs. Only when the, as yet unidentified, potential trigger with a fateful first oxidative step destroys oxygen evolution, will the ensuing cascade of structural perturbations of photosystem II destroy the proposed oxygen, water and proton pathways. Then oxygen has direct access to P(+)(680)Pheo(-), singlet oxygen will be produced and may successively oxidize specific amino acids of the phosphorylated D1 protein of photosystem II dimers that are confined to appressed granal domains, thereby targeting D1 protein for eventual degradation and replacement in non-appressed thylakoid domains.
Collapse
Affiliation(s)
- Jan M Anderson
- Photobioenergetics, Research School of Biological Sciences, Australian National University, GPO Box 475, Canberra ACT 2601, Australia.
| | | |
Collapse
|