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Garty Y, Bussi Y, Levin-Zaidman S, Shimoni E, Kirchhoff H, Charuvi D, Nevo R, Reich Z. Thylakoid membrane stacking controls electron transport mode during the dark-to-light transition by adjusting the distances between PSI and PSII. NATURE PLANTS 2024; 10:512-524. [PMID: 38396112 DOI: 10.1038/s41477-024-01628-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 01/23/2024] [Indexed: 02/25/2024]
Abstract
The balance between linear electron transport (LET) and cyclic electron transport (CET) plays an essential role in plant adaptation and protection against photo-induced damage. This balance is largely maintained by phosphorylation-driven alterations in the PSII-LHCII assembly and thylakoid membrane stacking. During the dark-to-light transition, plants shift this balance from CET, which prevails to prevent overreduction of the electron transport chain and consequent photo-induced damage, towards LET, which enables efficient CO2 assimilation and biomass production. Using freeze-fracture cryo-scanning electron microscopy and transmission electron microscopy of Arabidopsis leaves, we reveal unique membrane regions possessing characteristics of both stacked and unstacked regions of the thylakoid network that form during this transition. A notable consequence of the morphological attributes of these regions, which we refer to as 'stacked thylakoid doublets', is an overall increase in the proximity and connectivity of the two photosystems (PSI and PSII) that drive LET. This, in turn, reduces diffusion distances and barriers for the mobile carriers that transfer electrons between the two PSs, thereby maximizing LET and optimizing the plant's ability to utilize light energy. The mechanics described here for the shift between CET and LET during the dark-to-light transition are probably also used during chromatic adaptation mediated by state transitions.
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Affiliation(s)
- Yuval Garty
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Yuval Bussi
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Smadar Levin-Zaidman
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Helmut Kirchhoff
- Institute of Biological Chemistry, Washington State University, Pullman, WA, USA
| | - Dana Charuvi
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Institute, Rishon LeZion, Israel
| | - Reinat Nevo
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Ziv Reich
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
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2
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Bos PR, Berentsen J, Wientjes E. Expansion microscopy resolves the thylakoid structure of spinach. PLANT PHYSIOLOGY 2023; 194:347-358. [PMID: 37792700 PMCID: PMC10756755 DOI: 10.1093/plphys/kiad526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 09/19/2023] [Accepted: 09/19/2023] [Indexed: 10/06/2023]
Abstract
The light-harvesting reactions of photosynthesis take place on the thylakoid membrane inside chloroplasts. The thylakoid membrane is folded into appressed membranes, the grana, and nonappressed membranes that interconnect the grana, the stroma lamellae. This folding is essential for the correct functioning of photosynthesis. Electron microscopy and atomic force microscopy are commonly used to study the thylakoid membrane, but these techniques have limitations in visualizing a complete chloroplast and its organization. To overcome this limitation, we applied expansion microscopy (ExM) on isolated chloroplasts. ExM is a technique that involves physically expanding a sample in a swellable hydrogel to enhance the spatial resolution of fluorescence microscopy. Using all-protein staining, we visualized the 3D structure of spinach (Spinacia oleracea) thylakoids in detail. We were able to resolve stroma lamellae that were 60 nm apart and observe their helical wrapping around the grana. Furthermore, we accurately measured the dimensions of grana from top views of chloroplasts, which allow for precise determination of the granum diameter. Our results demonstrate that ExM is a fast and reliable technique for studying thylakoid organization in great detail.
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Affiliation(s)
- Peter R Bos
- Laboratory of Biophysics, Wageningen University & Research, Wageningen 6700 ET, The Netherlands
| | - Jarne Berentsen
- Laboratory of Biophysics, Wageningen University & Research, Wageningen 6700 ET, The Netherlands
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University & Research, Wageningen 6700 ET, The Netherlands
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3
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Bashir F, Rehman AU, Szabó M, Vass I. Singlet oxygen damages the function of Photosystem II in isolated thylakoids and in the green alga Chlorella sorokiniana. PHOTOSYNTHESIS RESEARCH 2021; 149:93-105. [PMID: 34009505 PMCID: PMC8382655 DOI: 10.1007/s11120-021-00841-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 04/26/2021] [Indexed: 06/12/2023]
Abstract
Singlet oxygen (1O2) is an important damaging agent, which is produced during illumination by the interaction of the triplet excited state pigment molecules with molecular oxygen. In cells of photosynthetic organisms 1O2 is formed primarily in chlorophyll containing complexes, and damages pigments, lipids, proteins and other cellular constituents in their environment. A useful approach to study the physiological role of 1O2 is the utilization of external photosensitizers. In the present study, we employed a multiwell plate-based screening method in combination with chlorophyll fluorescence imaging to characterize the effect of externally produced 1O2 on the photosynthetic activity of isolated thylakoid membranes and intact Chlorella sorokiniana cells. The results show that the external 1O2 produced by the photosensitization reactions of Rose Bengal damages Photosystem II both in isolated thylakoid membranes and in intact cells in a concentration dependent manner indicating that 1O2 plays a significant role in photodamage of Photosystem II.
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Affiliation(s)
- Faiza Bashir
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
- Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - Ateeq Ur Rehman
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
| | - Milán Szabó
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
- Climate Change Cluster, University of Technology Sydney, Sydney, Australia
| | - Imre Vass
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary.
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4
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Pipitone R, Eicke S, Pfister B, Glauser G, Falconet D, Uwizeye C, Pralon T, Zeeman SC, Kessler F, Demarsy E. A multifaceted analysis reveals two distinct phases of chloroplast biogenesis during de-etiolation in Arabidopsis. eLife 2021; 10:e62709. [PMID: 33629953 PMCID: PMC7906606 DOI: 10.7554/elife.62709] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 02/04/2021] [Indexed: 11/18/2022] Open
Abstract
Light triggers chloroplast differentiation whereby the etioplast transforms into a photosynthesizing chloroplast and the thylakoid rapidly emerges. However, the sequence of events during chloroplast differentiation remains poorly understood. Using Serial Block Face Scanning Electron Microscopy (SBF-SEM), we generated a series of chloroplast 3D reconstructions during differentiation, revealing chloroplast number and volume and the extent of envelope and thylakoid membrane surfaces. Furthermore, we used quantitative lipid and whole proteome data to complement the (ultra)structural data, providing a time-resolved, multi-dimensional description of chloroplast differentiation. This showed two distinct phases of chloroplast biogenesis: an initial photosynthesis-enabling 'Structure Establishment Phase' followed by a 'Chloroplast Proliferation Phase' during cell expansion. Moreover, these data detail thylakoid membrane expansion during de-etiolation at the seedling level and the relative contribution and differential regulation of proteins and lipids at each developmental stage. Altogether, we establish a roadmap for chloroplast differentiation, a critical process for plant photoautotrophic growth and survival.
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Affiliation(s)
- Rosa Pipitone
- Plant Physiology Laboratory, University of NeuchâtelNeuchâtelSwitzerland
| | - Simona Eicke
- Institute of Molecular Plant Biology, Department of Biology, ETH ZurichZurichSwitzerland
| | - Barbara Pfister
- Institute of Molecular Plant Biology, Department of Biology, ETH ZurichZurichSwitzerland
| | - Gaetan Glauser
- Neuchâtel Platform of Analytical Chemistry, University of NeuchâtelNeuchâtelSwitzerland
| | - Denis Falconet
- Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCVGrenobleFrance
| | - Clarisse Uwizeye
- Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCVGrenobleFrance
| | - Thibaut Pralon
- Plant Physiology Laboratory, University of NeuchâtelNeuchâtelSwitzerland
| | - Samuel C Zeeman
- Institute of Molecular Plant Biology, Department of Biology, ETH ZurichZurichSwitzerland
| | - Felix Kessler
- Plant Physiology Laboratory, University of NeuchâtelNeuchâtelSwitzerland
| | - Emilie Demarsy
- Plant Physiology Laboratory, University of NeuchâtelNeuchâtelSwitzerland
- Department of Botany and Plant Biology, University of GenevaGenevaSwitzerland
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5
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Onoa B, Fukuda S, Iwai M, Bustamante C, Niyogi KK. Atomic Force Microscopy Visualizes Mobility of Photosynthetic Proteins in Grana Thylakoid Membranes. Biophys J 2020; 118:1876-1886. [PMID: 32224302 PMCID: PMC7175462 DOI: 10.1016/j.bpj.2020.02.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/10/2020] [Accepted: 02/28/2020] [Indexed: 12/19/2022] Open
Abstract
Thylakoid membranes in chloroplasts contain photosynthetic protein complexes that convert light energy into chemical energy. Photosynthetic protein complexes are considered to undergo structural reorganization to maintain the efficiency of photochemical reactions. A detailed description of the mobility of photosynthetic complexes in real time is necessary to understand how macromolecular organization of the membrane is altered by environmental fluctuations. Here, we used high-speed atomic force microscopy to visualize and characterize the in situ mobility of individual protein complexes in grana thylakoid membranes isolated from Spinacia oleracea. Our observations reveal that these membranes can harbor complexes with at least two distinctive classes of mobility. A large fraction of grana membranes contained proteins with quasistatic mobility exhibiting molecular displacements smaller than 10 nm2. In the remaining fraction, the protein mobility is variable with molecular displacements of up to 100 nm2. This visualization at high spatiotemporal resolution enabled us to estimate an average diffusion coefficient of ∼1 nm2 s-1. Interestingly, both confined and Brownian diffusion models could describe the protein mobility of the second group of membranes. We also provide the first direct evidence, to our knowledge, of rotational diffusion of photosynthetic complexes. The rotational diffusion of photosynthetic complexes could be an adaptive response to the high protein density in the membrane to guarantee the efficiency of electron transfer reactions. This characterization of the mobility of individual photosynthetic complexes in grana membranes establishes a foundation that could be adapted to study the dynamics of the complexes inside intact and photosynthetically functional thylakoid membranes to be able to understand its structural responses to diverse environmental fluctuations.
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Affiliation(s)
- Bibiana Onoa
- Howard Hughes Medical Institute, University of California, Berkeley, California.
| | - Shingo Fukuda
- Howard Hughes Medical Institute, University of California, Berkeley, California
| | - Masakazu Iwai
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California; Department of Plant and Microbial Biology, University of California, Berkeley, California
| | - Carlos Bustamante
- Howard Hughes Medical Institute, University of California, Berkeley, California; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California; Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, California; Department of Molecular and Cell Biology, University of California, Berkeley, California; Department of Physics, University of California, Berkeley, California; Kavli Energy NanoScience Institute, Lawrence Berkeley National Laboratory, University of California, Berkeley, California
| | - Krishna K Niyogi
- Howard Hughes Medical Institute, University of California, Berkeley, California; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California; Department of Plant and Microbial Biology, University of California, Berkeley, California.
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6
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Macroorganisation and flexibility of thylakoid membranes. Biochem J 2019; 476:2981-3018. [DOI: 10.1042/bcj20190080] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 09/19/2019] [Accepted: 10/03/2019] [Indexed: 02/07/2023]
Abstract
Abstract
The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.
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7
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Strašková A, Steinbach G, Konert G, Kotabová E, Komenda J, Tichý M, Kaňa R. Pigment-protein complexes are organized into stable microdomains in cyanobacterial thylakoids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:148053. [PMID: 31344362 DOI: 10.1016/j.bbabio.2019.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/28/2019] [Accepted: 07/18/2019] [Indexed: 02/03/2023]
Abstract
Thylakoids are the place of the light-photosynthetic reactions. To gain maximal efficiency, these reactions are conditional to proper pigment-pigment and protein-protein interactions. In higher plants thylakoids, the interactions lead to a lateral asymmetry in localization of protein complexes (i.e. granal/stromal thylakoids) that have been defined as a domain-like structures characteristic by different biochemical composition and function (Albertsson P-Å. 2001,Trends Plant Science 6: 349-354). We explored this complex organization of thylakoid pigment-proteins at single cell level in the cyanobacterium Synechocystis sp. PCC 6803. Our 3D confocal images captured heterogeneous distribution of all main photosynthetic pigment-protein complexes (PPCs), Photosystem I (fluorescently tagged by YFP), Photosystem II and Phycobilisomes. The acquired images depicted cyanobacterial thylakoid membrane as a stable, mosaic-like structure formed by microdomains (MDs). These microcompartments are of sub-micrometer in sizes (~0.5-1.5 μm), typical by particular PPCs ratios and importantly without full segregation of observed complexes. The most prevailing MD is represented by MD with high Photosystem I content which allows also partial separation of Photosystems like in higher plants thylakoids. We assume that MDs stability (in minutes) provides optimal conditions for efficient excitation/electron transfer. The cyanobacterial MDs thus define thylakoid membrane organization as a system controlled by co-localization of three main PPCs leading to formation of thylakoid membrane mosaic. This organization might represent evolutional and functional precursor for the granal/stromal spatial heterogeneity in photosystems that is typical for higher plant thylakoids.
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Affiliation(s)
- A Strašková
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - G Steinbach
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - G Konert
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - E Kotabová
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - J Komenda
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - M Tichý
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - R Kaňa
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic.
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8
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Popova AV, Dobrev K, Velitchkova M, Ivanov AG. Differential temperature effects on dissipation of excess light energy and energy partitioning in lut2 mutant of Arabidopsis thaliana under photoinhibitory conditions. PHOTOSYNTHESIS RESEARCH 2019; 139:367-385. [PMID: 29725995 DOI: 10.1007/s11120-018-0511-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/22/2018] [Indexed: 06/08/2023]
Abstract
The high-light-induced alterations in photosynthetic performance of photosystem II (PSII) and photosystem I (PSI) as well as effectiveness of dissipation of excessive absorbed light during illumination for different periods of time at room (22 °C) and low (8-10 °C) temperature of leaves of Arabidopsis thaliana, wt and lut2, were followed with the aim of unraveling the role of lutein in the process of photoinhibition. Photosynthetic parameters of PSII and PSI were determined on whole leaves by PAM fluorometer and oxygen evolving activity-by a Clark-type electrode. In thylakoid membranes, isolated from non-illuminated and illuminated for 4.5 h leaves of wt and lut2 the photochemical activity of PSII and PSI and energy interaction between the main pigment-protein complexes was determined. Results indicate that in non-illuminated leaves of lut2 the maximum rate of oxygen evolution and energy utilization in PSII is lower, excitation pressure of PSII is higher and cyclic electron transport around PSI is faster than in wt leaves. Under high-light illumination, lut2 leaves are more sensitive in respect to PSII performance and the extent of increase of excitation pressure of PSII, ΦNO, and cyclic electron transport around PSI are higher than in wt leaves, especially when illumination is performed at low temperature. Significant part of the excessive light energy is dissipated via mechanism, not dependent on ∆pH and to functioning of xanthophyll cycle in LHCII, operating more intensively in lut2 leaves.
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Affiliation(s)
- Antoaneta V Popova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. bl. 21, 1113, Sofia, Bulgaria.
| | - Konstantin Dobrev
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. bl. 21, 1113, Sofia, Bulgaria
| | - Maya Velitchkova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. bl. 21, 1113, Sofia, Bulgaria
| | - Alexander G Ivanov
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. bl. 21, 1113, Sofia, Bulgaria
- Department of Biology, University of Western Ontario, 1151 Richmond Str. N., London, ON, N6A 5B7, Canada
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9
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Kirchhoff H, Li M, Puthiyaveetil S. Sublocalization of Cytochrome b 6f Complexes in Photosynthetic Membranes. TRENDS IN PLANT SCIENCE 2017; 22:574-582. [PMID: 28483636 DOI: 10.1016/j.tplants.2017.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 05/17/2023]
Abstract
It is well established that the majority of energy-converting photosynthetic protein complexes in plant thylakoid membrane are nonhomogenously distributed between stacked and unstacked membrane regions. Yet, the sublocalization of the central cytochrome b6f complex remains controversial. We present a structural model that explains the variation in cytochrome b6f sublocalization data. Small changes in the distance between adjacent membranes in stacked grana regions either allow or restrict access of cytochrome b6f complexes to grana. If the width of the gap falls below a certain threshold, then the steric hindrance prevents cytochrome b6f access to grana. Evidence is presented that the width of stromal gap is variable, demonstrating that the postulated mechanism can regulate the lateral distribution of the cytochrome b6f complexes.
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Affiliation(s)
- Helmut Kirchhoff
- Insitute of Biological Chemistry, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA.
| | - Meng Li
- Insitute of Biological Chemistry, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA
| | - Sujith Puthiyaveetil
- Insitute of Biological Chemistry, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA; Current address: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, IN 47907, USA
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10
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Bose J, Munns R, Shabala S, Gilliham M, Pogson B, Tyerman SD. Chloroplast function and ion regulation in plants growing on saline soils: lessons from halophytes. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3129-3143. [PMID: 28472512 DOI: 10.1093/jxb/erx142] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Salt stress impacts multiple aspects of plant metabolism and physiology. For instance it inhibits photosynthesis through stomatal limitation, causes excessive accumulation of sodium and chloride in chloroplasts, and disturbs chloroplast potassium homeostasis. Most research on salt stress has focused primarily on cytosolic ion homeostasis with few studies of how salt stress affects chloroplast ion homeostasis. This review asks the question whether membrane-transport processes and ionic relations are differentially regulated between glycophyte and halophyte chloroplasts and whether this contributes to the superior salt tolerance of halophytes. The available literature indicates that halophytes can overcome stomatal limitation by switching to CO2 concentrating mechanisms and increasing the number of chloroplasts per cell under saline conditions. Furthermore, salt entry into the chloroplast stroma may be critical for grana formation and photosystem II activity in halophytes but not in glycophytes. Salt also inhibits some stromal enzymes (e.g. fructose-1,6-bisphosphatase) to a lesser extent in halophyte species. Halophytes accumulate more chloride in chloroplasts than glycophytes and appear to use sodium in functional roles. We propose the molecular identities of candidate transporters that move sodium, chloride and potassium across chloroplast membranes and discuss how their operation may regulate photochemistry and photosystem I and II activity in chloroplasts.
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Affiliation(s)
- Jayakumar Bose
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia
| | - Rana Munns
- Australian Research Council Centre of Excellence in Plant Energy Biology, and School of Agriculture and Environment, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Sergey Shabala
- School of Land and Food, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia
| | - Matthew Gilliham
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia
| | - Barry Pogson
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Stephen D Tyerman
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia
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11
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Live-cell visualization of excitation energy dynamics in chloroplast thylakoid structures. Sci Rep 2016; 6:29940. [PMID: 27416900 PMCID: PMC4945916 DOI: 10.1038/srep29940] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/27/2016] [Indexed: 11/09/2022] Open
Abstract
The intricate molecular processes underlying photosynthesis have long been studied using various analytic approaches. However, the three-dimensional (3D) dynamics of such photosynthetic processes remain unexplored due to technological limitations related to investigating intraorganellar mechanisms in vivo. By developing a system for high-speed 3D laser scanning confocal microscopy combined with high-sensitivity multiple-channel detection, we visualized excitation energy dynamics in thylakoid structures within chloroplasts of live Physcomitrella patens cells. Two distinct thylakoid structures in the chloroplast, namely the grana and stroma lamellae, were visualized three-dimensionally in live cells. The simultaneous detection of the shorter (than ~670 nm) and longer (than ~680 nm) wavelength regions of chlorophyll (Chl) fluorescence reveals different spatial characteristics-irregular and vertical structures, respectively. Spectroscopic analyses showed that the shorter and longer wavelength regions of Chl fluorescence are affected more by free light-harvesting antenna proteins and photosystem II supercomplexes, respectively. The high-speed 3D time-lapse imaging of the shorter and longer wavelength regions also reveals different structural dynamics-rapid and slow movements within 1.5 seconds, respectively. Such structural dynamics of the two wavelength regions of Chl fluorescence would indicate excitation energy dynamics between light-harvesting antenna proteins and photosystems, reflecting the energetically active nature of photosynthetic proteins in thylakoid membranes.
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12
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Dobrev K, Stanoeva D, Velitchkova M, Popova AV. The Lack of Lutein Accelerates the Extent of Light-induced Bleaching of Photosynthetic Pigments in Thylakoid Membranes of Arabidopsis thaliana. Photochem Photobiol 2016; 92:436-45. [PMID: 26888623 DOI: 10.1111/php.12576] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/24/2016] [Indexed: 11/30/2022]
Abstract
The high light-induced bleaching of photosynthetic pigments and the degradation of proteins of light-harvesting complexes of PSI and PSII were investigated in isolated thylakoid membranes of Arabidopsis thaliana, wt and lutein-deficient mutant lut2, with the aim of unraveling the role of lutein for the degree of bleaching and degradation. By the means of absorption spectroscopy and western blot analysis, we show that the lack of lutein leads to a higher extent of pigment photobleaching and protein degradation in mutant thylakoid membranes in comparison with wt. The highest extent of bleaching is suffered by chlorophyll a and carotenoids, while chlorophyll b is bleached in lut2 thylakoids during long periods at high illumination. The high light-induced degradation of Lhca1, Lhcb2 proteins and PsbS was followed and it is shown that Lhca1 is more damaged than Lhcb2. The degradation of analyzed proteins is more pronounced in lut2 mutant thylakoid membranes. The lack of lutein influences the high light-induced alterations in organization of pigment-protein complexes as revealed by 77 K fluorescence.
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Affiliation(s)
- Konstantin Dobrev
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. Bl. 21, Sofia, 1113, Bulgaria
| | - Daniela Stanoeva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. Bl. 21, Sofia, 1113, Bulgaria
| | - Maya Velitchkova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. Bl. 21, Sofia, 1113, Bulgaria
| | - Antoaneta V Popova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. Bl. 21, Sofia, 1113, Bulgaria
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13
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Jia H, Liggins JR, Chow WS. Entropy and biological systems: experimentally-investigated entropy-driven stacking of plant photosynthetic membranes. Sci Rep 2014; 4:4142. [PMID: 24561561 PMCID: PMC5379253 DOI: 10.1038/srep04142] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 02/03/2014] [Indexed: 11/28/2022] Open
Abstract
According to the Second Law of Thermodynamics, an overall increase of entropy contributes to the driving force for any physicochemical process, but entropy has seldom been investigated in biological systems. Here, for the first time, we apply Isothermal Titration Calorimetry (ITC) to investigate the Mg2+-induced spontaneous stacking of photosynthetic membranes isolated from spinach leaves. After subtracting a large endothermic interaction of MgCl2 with membranes, unrelated to stacking, we demonstrate that the enthalpy change (heat change at constant pressure) is zero or marginally positive or negative. This first direct experimental evidence strongly suggests that an entropy increase significantly drives membrane stacking in this ordered biological structure. Possible mechanisms for the entropy increase include: (i) the attraction between discrete oppositely-charged areas, releasing counterions; (ii) the release of loosely-bound water molecules from the inter-membrane gap; (iii) the increased orientational freedom of previously-aligned water dipoles; and (iv) the lateral rearrangement of membrane components.
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Affiliation(s)
- Husen Jia
- 1] Division of Plant Science, R. N. Robertson Building (46), Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia [2]
| | - John R Liggins
- 1] Division of Plant Science, R. N. Robertson Building (46), Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia [2]
| | - Wah Soon Chow
- Division of Plant Science, R. N. Robertson Building (46), Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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14
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Iwai M, Yokono M, Nakano A. Visualizing structural dynamics of thylakoid membranes. Sci Rep 2014; 4:3768. [PMID: 24442007 PMCID: PMC3895878 DOI: 10.1038/srep03768] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 12/27/2013] [Indexed: 11/10/2022] Open
Abstract
To optimize photosynthesis, light-harvesting antenna proteins regulate light energy dissipation and redistribution in chloroplast thylakoid membranes, which involve dynamic protein reorganization of photosystems I and II. However, direct evidence for such protein reorganization has not been visualized in live cells. Here we demonstrate structural dynamics of thylakoid membranes by live cell imaging in combination with deconvolution. We observed chlorophyll fluorescence in the antibiotics-induced macrochloroplast in the moss Physcomitrella patens. The three-dimensional reconstruction uncovered the fine thylakoid membrane structure in live cells. The time-lapse imaging shows that the entire thylakoid membrane network is structurally stable, but the individual thylakoid membrane structure is flexible in vivo. Our observation indicates that grana serve as a framework to maintain structural integrity of the entire thylakoid membrane network. Both the structural stability and flexibility of thylakoid membranes would be essential for dynamic protein reorganization under fluctuating light environments.
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Affiliation(s)
- Masakazu Iwai
- 1] Live Cell Molecular Imaging Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan [2] PRESTO, Japan Science and Technology Agency (JST), Honcho, Kawaguchi, Saitama 332-0012 Japan
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido 060-0819 Japan
| | - Akihiko Nakano
- 1] Live Cell Molecular Imaging Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan [2] Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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15
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Anderson JM. Lateral heterogeneity of plant thylakoid protein complexes: early reminiscences. Philos Trans R Soc Lond B Biol Sci 2013; 367:3384-8. [PMID: 23148264 DOI: 10.1098/rstb.2012.0060] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The concept that the two photosystems of photosynthesis cooperate in series, immortalized in Hill and Bendall's Z scheme, was still a black box that defined neither the structural nor the molecular organization of the thylakoid membrane network into grana and stroma thylakoids. The differentiation of the continuous thylakoid membrane into stacked grana thylakoids interconnected by single stroma thylakoids is a morphological reflection of the non-random distribution of photosystem II/light-harvesting complex of photosystem II, photosystem I and ATP synthase, which became known as lateral heterogeneity.
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Affiliation(s)
- Jan M Anderson
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia. *
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16
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Jia H, Liggins JR, Chow WS. Acclimation of leaves to low light produces large grana: the origin of the predominant attractive force at work. Philos Trans R Soc Lond B Biol Sci 2013; 367:3494-502. [PMID: 23148276 DOI: 10.1098/rstb.2012.0071] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Photosynthetic membrane sacs (thylakoids) of plants form granal stacks interconnected by non-stacked thylakoids, thereby being able to fine-tune (i) photosynthesis, (ii) photoprotection and (iii) acclimation to the environment. Growth in low light leads to the formation of large grana, which sometimes contain as many as 160 thylakoids. The net surface charge of thylakoid membranes is negative, even in low-light-grown plants; so an attractive force is required to overcome the electrostatic repulsion. The theoretical van der Waals attraction is, however, at least 20-fold too small to play the role. We determined the enthalpy change, in the spontaneous stacking of previously unstacked thylakoids in the dark on addition of Mg(2+), to be zero or marginally positive (endothermic). The Gibbs free-energy change for the spontaneous process is necessarily negative, a requirement that can be met only by an increase in entropy for an endothermic process. We conclude that the dominant attractive force in thylakoid stacking is entropy-driven. Several mechanisms for increasing entropy upon stacking of thylakoid membranes in the dark, particularly in low-light plants, are discussed. In the light, which drives the chloroplast far away from equilibrium, granal stacking accelerates non-cyclic photophosphorylation, possibly enhancing the rate at which entropy is produced.
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Affiliation(s)
- Husen Jia
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
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17
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Nevo R, Charuvi D, Tsabari O, Reich Z. Composition, architecture and dynamics of the photosynthetic apparatus in higher plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 70:157-76. [PMID: 22449050 DOI: 10.1111/j.1365-313x.2011.04876.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The process of oxygenic photosynthesis enabled and still sustains aerobic life on Earth. The most elaborate form of the apparatus that carries out the primary steps of this vital process is the one present in higher plants. Here, we review the overall composition and supramolecular organization of this apparatus, as well as the complex architecture of the lamellar system within which it is harbored. Along the way, we refer to the genetic, biochemical, spectroscopic and, in particular, microscopic studies that have been employed to elucidate the structure and working of this remarkable molecular energy conversion device. As an example of the highly dynamic nature of the apparatus, we discuss the molecular and structural events that enable it to maintain high photosynthetic yields under fluctuating light conditions. We conclude the review with a summary of the hypotheses made over the years about the driving forces that underlie the partition of the lamellar system of higher plants and certain green algae into appressed and non-appressed membrane domains and the segregation of the photosynthetic protein complexes within these domains.
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Affiliation(s)
- Reinat Nevo
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
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18
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Adam Z, Charuvi D, Tsabari O, Knopf RR, Reich Z. Biogenesis of thylakoid networks in angiosperms: knowns and unknowns. PLANT MOLECULAR BIOLOGY 2011; 76:221-34. [PMID: 20859754 DOI: 10.1007/s11103-010-9693-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Accepted: 09/10/2010] [Indexed: 05/06/2023]
Abstract
Aerobic life on Earth depends on oxygenic photosynthesis. This fundamentally important process is carried out within an elaborate membranous system, called the thylakoid network. In angiosperms, thylakoid networks are constructed almost from scratch by an intricate, light-dependent process in which lipids, proteins, and small organic molecules are assembled into morphologically and functionally differentiated, three-dimensional lamellar structures. In this review, we summarize the major events that occur during this complex, largely elusive process, concentrating on those that are directly involved in network formation and potentiation and highlighting gaps in our knowledge, which, as hinted by the title, are substantial.
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Affiliation(s)
- Zach Adam
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, 76100 Rehovot, Israel.
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19
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Daum B, Kühlbrandt W. Electron tomography of plant thylakoid membranes. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:2393-402. [PMID: 21441405 DOI: 10.1093/jxb/err034] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
For more than half a century, electron microscopy has been a main tool for investigating the complex ultrastructure and organization of chloroplast thylakoid membranes, but, even today, the three-dimensional relationship between stroma and grana thylakoids, and the arrangement of the membrane protein complexes within them are not fully understood. Electron cryo-tomography (cryo-ET) is a powerful new technique for visualizing cellular structures, especially membranes, in three dimensions. By this technique, large membrane protein complexes, such as the photosystem II supercomplex or the chloroplast ATP synthase, can be visualized directly in the thylakoid membrane at molecular (4-5 nm) resolution. This short review compares recent advances by cryo-ET of plant thylakoid membranes with earlier results obtained by conventional electron microscopy.
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Affiliation(s)
- Bertram Daum
- Max Planck Institute of Biophysics, D-60438 Frankfurt am Main, Germany
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20
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Cui YL, Jia QS, Yin QQ, Lin GN, Kong MM, Yang ZN. The GDC1 gene encodes a novel ankyrin domain-containing protein that is essential for grana formation in Arabidopsis. PLANT PHYSIOLOGY 2011; 155:130-41. [PMID: 21098677 PMCID: PMC3075748 DOI: 10.1104/pp.110.165589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In land-plant chloroplasts, the grana play multiple roles in photosynthesis, including the potential increase of photosynthetic capacity in light and enhancement of photochemical efficiency in shade. However, the molecular mechanisms of grana formation remain elusive. Here, we report a novel gene, Grana-Deficient Chloroplast1 (GDC1), required for chloroplast grana formation in Arabidopsis (Arabidopsis thaliana). In the chloroplast of knockout mutant gdc1-3, only stromal thylakoids were observed, and they could not stack together to form appressed grana. The mutant exhibited seedling lethality with pale green cotyledons and true leaves. Further blue native-polyacrylamide gel electrophoresis analysis indicated that the trimeric forms of Light-Harvesting Complex II (LHCII) were scarcely detected in gdc1-3, confirming previous reports that the LHCII trimer is essential for grana formation. The Lhcb1 protein, the major component of the LHCIIb trimer, was substantially reduced, and another LHCIIb trimer component, Lhcb2, was slightly reduced in the gdc1-3 mutant, although their transcription levels were not altered in the mutant. This suggests that defective LHCII trimer formation in gdc1-3 is due to low amounts of Lhcb1 and Lhcb2. GDC1 encodes a chloroplast protein with an ankyrin domain within the carboxyl terminus. It was highly expressed in Arabidopsis green tissues, and its expression was induced by photosignaling pathways. Immunoblot analysis of the GDC1-green fluorescent protein (GFP) fusion protein in 35S::GDC1-GFP transgenic plants with GFP antibody indicates that GDC1 is associated with an approximately 440-kD thylakoid protein complex instead of the LHCII trimer. This shows that GDC1 may play an indirect role in LHCII trimerization during grana formation.
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21
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Liu XJ, Duan SS, Li AF, Sun KF. Effects of glycerol on the fluorescence spectra and chloroplast ultrastructure of Phaeodactylum tricornutum (Bacillariophyta). JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2009; 51:272-278. [PMID: 19261070 DOI: 10.1111/j.1744-7909.2008.00767.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Responses of the photosynthetic activity of Phaeodactylum tricornutum (Bacillariophyta) to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloroplast ultrastructure of P. tricornutum were examined under photoautotrophic, mixotrophic, and photoheterotrophic conditions. The results showed that the specific growth rate was the fastest under mixotrophic conditions. The cell photosynthetic pigment content and values of Chl a/Chl c were reduced under mixotrophic and photoheterotrophic conditions. The value of carotenoid/Chl a was enhanced under mixotrophic conditions, but was decreased under photoheterotrophic conditions. In comparison with photoautotrophic conditions, the fluorescence emission peaks and fluorescence excitation peaks were not shifted. The relative fluorescence of photosystem (PS) I and PS II and the values of F685/F710 and F685/F738 were decreased. Chloroplast thylakoid pairs were less packed under mixotrophic and photoheterotrophic conditions. There was a strong correlation between degree of chloroplast thylakoid packing and the excitation energy kept in PS II. These results suggested that the PS II activity was reduced by glycerol under mixotrophic conditions, thereby leading to repression of the photosynthetic activity.
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Affiliation(s)
- Xiao-Juan Liu
- Institute of Hydrobiology, Jinan University, Guangzhou 510632, China
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22
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Nevo R, Chuartzman SG, Tsabari O, Reich Z, Charuvi D, Shimoni E. Architecture of Thylakoid Membrane Networks. LIPIDS IN PHOTOSYNTHESIS 2009. [DOI: 10.1007/978-90-481-2863-1_14] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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23
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Anderson JM, Chow WS, De Las Rivas J. Dynamic flexibility in the structure and function of photosystem II in higher plant thylakoid membranes: the grana enigma. PHOTOSYNTHESIS RESEARCH 2008; 98:575-87. [PMID: 18998237 DOI: 10.1007/s11120-008-9381-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 10/09/2008] [Indexed: 05/10/2023]
Abstract
Grana are not essential for photosynthesis, yet they are ubiquitous in higher plants and in the recently evolved Charaphyta algae; hence grana role and its need is still an intriguing enigma. This article discusses how the grana provide integrated and multifaceted functional advantages, by facilitating mechanisms that fine-tune the dynamics of the photosynthetic apparatus, with particular implications for photosystem II (PSII). This dynamic flexibility of photosynthetic membranes is advantageous in plants responding to ever-changing environmental conditions, from darkness or limiting light to saturating light and sustained or intermittent high light. The thylakoid dynamics are brought about by structural and organizational changes at the level of the overall height and number of granal stacks per chloroplast, molecular dynamics within the membrane itself, the partition gap between appressed membranes within stacks, the aqueous lumen encased by the continuous thylakoid membrane network, and even the stroma bathing the thylakoids. The structural and organizational changes of grana stacks in turn are driven by physicochemical forces, including entropy, at work in the chloroplast. In response to light, attractive van der Waals interactions and screening of electrostatic repulsion between appressed grana thylakoids across the partition gap and most probably direct protein interactions across the granal lumen (PSII extrinsic proteins OEEp-OEEp, particularly PsbQ-PsbQ) contribute to the integrity of grana stacks. We propose that both the light-induced contraction of the partition gap and the granal lumen elicit maximisation of entropy in the chloroplast stroma, thereby enhancing carbon fixation and chloroplast protein synthesizing capacity. This spatiotemporal dynamic flexibility in the structure and function of active and inactive PSIIs within grana stacks in higher plant chloroplasts is vital for the optimization of photosynthesis under a wide range of environmental and developmental conditions.
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Affiliation(s)
- Jan M Anderson
- Research School of Biological Sciences, The College of Science, Australian National University, Canberra, ACT 2601, Australia.
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24
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Mullineaux CW. Function and evolution of grana. TRENDS IN PLANT SCIENCE 2005; 10:521-5. [PMID: 16169274 DOI: 10.1016/j.tplants.2005.09.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 07/15/2005] [Accepted: 09/08/2005] [Indexed: 05/04/2023]
Abstract
Chloroplasts are descended from cyanobacteria, and they retain many features of the cyanobacterial photosynthetic apparatus. However, land-plant chloroplasts have a strikingly different thylakoid membrane organization to that of cyanobacteria. Usually the two photosystems are laterally segregated; Photosystem II is concentrated in complex stacked-membrane structures known as grana. The function of grana has long been debated. Recent studies on membrane organization in chloroplasts, cyanobacteria and purple bacteria now offer a new perspective. I argue that grana allow the presence of a large light-harvesting antenna for Photosystem II, without excessively restricting electron transport. Other organisms solve this problem in different ways. Land plants evolved from macroalgae that were adapted to high light conditions; they evolved grana as a new solution to the problem of efficient photosynthesis in shade.
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Affiliation(s)
- Conrad W Mullineaux
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
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25
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Velitchkova M, Popova A. High light-induced changes of 77 K fluorescence emission of pea thylakoid membranes with altered membrane fluidity. Bioelectrochemistry 2005; 67:81-90. [PMID: 15886067 DOI: 10.1016/j.bioelechem.2004.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 11/19/2004] [Accepted: 12/02/2004] [Indexed: 10/25/2022]
Abstract
The effect of lipid phase order of isolated thylakoid membranes on fluorescent characteristics of both photosystems during illumination with high light intensity at 22 degrees C and 4 degrees C was investigated. For artificial modification of membrane fluidity two membrane perturbing agents were applied-cholesterol and benzyl alcohol. 77 K fluorescence emission and excitation spectra of control, cholesterol- and benzyl alcohol-treated thylakoid membranes were analysed in order to determine the high light-induced changes of emission bands attributed to different chlorophyll-protein complexes-F 735, emitted by photosystem I-light-harvesting complex I; and F 685 and F 695, emitted by photosystem II-light-harvesting complex II. Analysis of emission bands showed that high light treatment leads to a decrease of the area of band at 695 nm and a concomitant increase of intensity of the band at 735 nm. The involvement of different pigment pools (chlorophyll a and chlorophyll b) in the energy supply of both photosystems before and after photoinhibitory treatment was estimated on the basis of excitation fluorescence spectra. The dependence of the ratios F 735/F 685 and the band areas at 685 and 695 nm on the illumination time was studied at both temperatures. Data presented indicate that cholesterol incorporation stabilized the intersystem structure in respect to light-induced changes of fluorescence emission of PSI and PSII. It was shown that the effect of fluid properties of thylakoid membranes on the 77 K fluorescence characteristics of main pigment protein complexes of pea thyalkoid membranes depends on the temperature during high light treatment.
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Affiliation(s)
- Maya Velitchkova
- Institute of Biophysics, Bulgarian Academy of Sciences, Acad. G. Bonchev str. bl. 21, 1113 Sofia, Bulgaria.
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26
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Chow WS, Kim EH, Horton P, Anderson JM. Granal stacking of thylakoid membranes in higher plant chloroplasts: the physicochemical forces at work and the functional consequences that ensue. Photochem Photobiol Sci 2005; 4:1081-90. [PMID: 16307126 DOI: 10.1039/b507310n] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of grana in chloroplasts of higher plants is examined in terms of the subtle interplay of physicochemical forces of attraction and repulsion. The attractive forces between two adjacent membranes comprise (1) van der Waals attraction that depends on the abundance and type of atoms in each membrane, on the distance between the membranes and on the dielectric constant, (2) depletion attraction that generates local order by granal stacking at the expense of greater disorder (i.e. entropy) in the stroma, and (3) an electrostatic attraction of opposite charges located on adjacent membranes. The repulsive forces comprise (1) electrostatic repulsion due to the net negative charge on the outer surface of thylakoid membranes, (2) hydration repulsion that operates at small separations between thylakoid membranes due to layers of bound water molecules, and (3) steric hindrance due to bulky protrusions of Photosystem I (PSI) and ATP synthase into the stroma. In addition, specific interactions may occur, but they await experimental demonstration. Although grana are not essential for photosynthesis, they are ubiquitous in higher plants. Grana may have been selected during evolution for the functional advantages that they confer on higher plants. The functional consequences of grana stacking include (1) enhancement of light capture through a vastly increased area-to-volume ratio and connectivity of several PSIIs with large functional antenna size, (2) the ability to control the lateral separation of PSI from PSII and, therefore, the balanced distribution of excitation energy between two photosystems working in series, (3) the reversible fine-tuning of energy distribution between the photosystems by State 1-State 2 transitions, (4) the ability to regulate light-harvesting via controlled thermal dissipation of excess excitation energy, detected as non-photochemical quenching, (5) dynamic flexibility in the light reactions mediated by a granal structure in response to regulation by a trans-thylakoid pH gradient, (6) delaying the premature degradation of D1 and D2 reaction-centre protein(s) in PSII by harbouring photoinactived PSIIs in appressed granal domains, (7) enhancement of the rate of non-cyclic synthesis of adenosine triphosphate (ATP) as well as the regulation of non-cyclic vs. cyclic ATP synthesis, and (8) the potential increase of photosynthetic capacity for a given composition of chloroplast constituents in full sunlight, concomitantly with enhancement of photochemical efficiency in canopy shade. Hence chloroplast ultrastructure and function are intimately intertwined.
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Affiliation(s)
- Wah Soon Chow
- Photobioenergetics Group, Research School of Biological Sciences, GPO Box 475, Canberra, ACT 2601, Australia.
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Prakash JSS, Baig MA, Bhagwat AS, Mohanty P. Characterisation of senescence-induced changes in light harvesting complex II and photosystem I complex of thylakoids of Cucumis sativus cotyledons: age induced association of LHCII with photosystem I. JOURNAL OF PLANT PHYSIOLOGY 2003; 160:175-184. [PMID: 12685033 DOI: 10.1078/0176-1617-00529] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Structure and function of chloroplasts are known to after during senescence. The senescence-induced specific changes in light harvesting antenna of photosystem II (PSII) and photosystem I (PSI) were investigated in Cucumis cotyledons. Purified light harvesting complex II (LHCII) and photosystem I complex were isolated from 6-day non-senescing and 27-day senescing Cucumis cotyledons. The chlorophyll a/b ratio of LHCII obtained from 6-day-old control cotyledons and their absorption, chlorophyll a fluorescence emission and the circular dichroism (CD) spectral properties were comparable to the LHCII preparations from other plants such as pea and spinach. The purified LHCII obtained from 27-day senescing cotyledons had a Chl a/b ratio of 1.25 instead of 1.2 as with 6-day LHCII and also exhibited significant changes in the visible CD spectrum compared to that of 6-day LHCII, indicating some specific alterations in the organisation of chlorophylls of LHCII. The light harvesting antenna of photosystems are likely to be altered due to aging. The room temperature absorption spectrum of LHCII obtained from 27-day senescing cotyledons showed changes in the peak positions. Similarly, comparison of 77K chlorophyll a fluorescence emission characteristics of LHCII preparation from senescing cotyledons with that of control showed a small shift in the peak position and the alteration in the emission profile, which is suggestive of possible changes in energy transfer within LHCII chlorophylls. Further, the salt induced aggregation of LHCII samples was lower, resulting in lower yields of LHCII from 27-day cotyledons than from normal cotyledons. Moreover, the PSI preparations of 6-day cotyledons showed Chl a/b ratios of 5 to 5.5, where as the PSI sample of 27-day cotyledons had a Chl a/b ratio of 2.9 suggesting LHCII association with PSI. The absorption, fluorescence emission and visible CD spectral measurements as well as the polypeptide profiles of 27-day cotyledon-PSI complexes indicated age-induced association of LHCII of PSII with PSI obtained from 27-day cotyledons. We modified our isolation protocols by increasing the duration of detergent Triton X-100 treatment for preparing the PSI and LHCII complexes from 27-day cotyledons. However, the PSI complexes isolated from senescing samples invariably proved to have significantly low Chl a/b ratio suggesting an age induced lateral movement and possible association of LHCII with PSI complexes. The analyses of polypeptide compositions of LHCII and PSI holocomplexes isolated from 6-day control and 27-day senescing cotyledons showed distinctive differences in their profiles. The presence of 26-28 kDa polypeptide in PSI complexes from 27-day cotyledons, but not in 6-day control PSI complexes is in agreement with the notion that senescence induced migration of LHCII to stroma lamellae and its possible association with PSI. We suggest that the migration of LHCII to the stroma lamellae region and its possible association with PSI might cause the destacking and flattening of grana structure during senescence of the chloroplasts. Such structural changes in light harvesting antenna are likely to alter energy transfer between two photosystems. The nature of aging induced migration and association of LHCII with PSI and its existence in other senescing systems need to be estimated in the future.
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Green BR, Anderson JM, Parson WW. Photosynthetic Membranes and Their Light-Harvesting Antennas. LIGHT-HARVESTING ANTENNAS IN PHOTOSYNTHESIS 2003. [DOI: 10.1007/978-94-017-2087-8_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Rojdestvenski I, Ivanov AG, Cottam MG, Borodich A, Huner NPA, Oquist G. Segregation of photosystems in thylakoid membranes as a critical phenomenon. Biophys J 2002; 82:1719-30. [PMID: 11916833 PMCID: PMC1301971 DOI: 10.1016/s0006-3495(02)75524-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The distribution of the two photosystems, PSI and PSII, in grana and stroma lamellae of the chloroplast membranes is not uniform. PSII are mainly concentrated in grana and PSI in stroma thylakoids. The dynamics and factors controlling the spatial segregation of PSI and PSII are generally not well understood, and here we address the segregation of photosystems in thylakoid membranes by means of a molecular dynamics method. The lateral segregation of photosystems was studied assuming a model comprising a two-dimensional (in-plane), two-component, many-body system with periodic boundary conditions and competing interactions between the photosystems in the thylakoid membrane. PSI and PSII are represented by particles with different values of negative charge. The pair interactions between particles include a screened Coulomb repulsive part and an exponentially decaying attractive part. The modeling results suggest a complicated phase behavior of the system, including quasi-crystalline phase of randomly distributed complexes of PSII and PSI at low ionic screening, well defined clustered state of segregated complexes at high screening, and in addition, an intermediate agglomerate phase where the photosystems tend to aggregate together without segregation. The calculations demonstrated that the ordering of photosystems within the membrane was the result of interplay between electrostatic and lipid-mediated interactions. At some values of the model parameters the segregation can be represented visually as well as by analyzing the correlation functions of the configuration.
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30
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Murphy DJ. The importance of non-planar bilayer regions in photosynthetic membranes and their stabilisation by galactolipids. FEBS Lett 2001. [DOI: 10.1016/0014-5793(82)81297-0] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Dominy P, Williams W. The relationship between changes in the redox state of plastoquinone and control of excitation energy distribution in photosynthesis. FEBS Lett 2001. [DOI: 10.1016/0014-5793(85)80543-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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32
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Gounaris K, Sundby C, Andersson B, Barber J. Lateral heterogeneity of polar lipids in the thylakoid membranes of spinach chloroplasts. FEBS Lett 2001. [DOI: 10.1016/0014-5793(83)80271-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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33
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34
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Mansfield R, Nakatani H, Barber J, Mauro S, Lannoye R. Charge density on the inner surface of pea thylakoid membranes. FEBS Lett 2001. [DOI: 10.1016/0014-5793(82)80331-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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35
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Anderson JM. Distribution of the cytochromes of spinach chloroplasts between the appressed membranes of grana stacks and stroma-exposed thylakoid regions. FEBS Lett 2001. [DOI: 10.1016/0014-5793(82)80395-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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36
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Andersson B, Haehnel W. Location of photosystem I and photosystem II reaction centers in different thylakoid regions of stacked chloroplasts. FEBS Lett 2001. [DOI: 10.1016/0014-5793(82)80695-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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37
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Allen JF, Forsberg J. Molecular recognition in thylakoid structure and function. TRENDS IN PLANT SCIENCE 2001; 6:317-26. [PMID: 11435171 DOI: 10.1016/s1360-1385(01)02010-6] [Citation(s) in RCA: 278] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In photosynthesis, light-harvesting chlorophyll molecules are shunted between photosystems by phosphorylation of the protein to which they are bound. An anchor for the phosphorylated chlorophyll-protein complex has now been identified in the reaction centre of chloroplast photosystem I. This finding supports the idea that molecular recognition, not membrane surface charge, governs the architecture of the chloroplast thylakoid membrane. We describe a model for the chloroplast thylakoid membrane that is consistent with recent structural data that specify the relative dimensions of intrinsic protein complexes and their dispositions within the membrane. Control of molecular recognition accommodates membrane stacking, lateral heterogeneity and regulation of light-harvesting function by means of protein phosphorylation during state transitions--adaptations that compensate for selective excitation of photosystem I or photosystem II. High-resolution structural description of membrane protein-protein interactions is now required to understand thylakoid structure and regulation of photosynthesis.
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Affiliation(s)
- J F Allen
- Plant Biochemistry, Lund University, Box 117, SE-221 00, Lund, Sweden.
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40
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Cherkashin AA, Bulychev AA, Vredenberg WJ. Outward photocurrent component in chloroplasts of Peperomia metallica and its assignment to the 'closed thylakoid' recording configuration. BIOELECTROCHEMISTRY AND BIOENERGETICS (LAUSANNE, SWITZERLAND) 1999; 48:141-8. [PMID: 10228581 DOI: 10.1016/s0302-4598(98)00226-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The photoinduced electrical events at energy-conserving chloroplast membranes can be studied in whole plastids using suction electrodes. In chloroplasts of Peperomia metallica the kinetic profile of photocurrent contains a minor outward component that occurs prior to and differs in polarity from the main component. The origin of this outward current was analyzed using single-turnover flashes in combination with prolonged light exposures and differential physicochemical treatments of tip-located (internal) and the exposed parts of a chloroplast. The outward current signal was higher after 10- to 20-s preillumination and gradually reduced in darkness. The relative amplitude of the outward peak current was enhanced when photosystem II (PS II) was excited by flashes given in the presence of far-red background light (lambda = 712 nm). The outward current was small or absent under conditions promoting activity of photosystem I (cyclic electron transport supported by artificial redox mediators in the presence of diuron) and was particularly high in the presence of PS II electron acceptors (e.g., p-phenylenediamine). This indicates the predominant association of the outward current with activity of PS II. The external application of diuron strongly inhibited the inward current, giving rise to a temporal increase in the outward current. On the contrary, when diuron was added into the suction pipette, the outward current was inhibited soon after sealing. The data suggest that the outward current originated in the tip-located portions of the thylakoid membrane that have orientation opposite to the exposed part of 'whole thylakoid'. These tip-located membrane portions are least accessible for inhibitors added into the outer medium and are highly sensitive to inhibitors (diuron), ionophores (gramicidin D), and detergents (Triton X-100) added into the pipette. Differential involvement of two photosystems in generation of the outward current may be caused by uneven structural distribution of photosystems I and II between appressed (granal) and nonappressed (stromal) thylakoids and by different recording configurations for these thylakoids.
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Affiliation(s)
- A A Cherkashin
- Biophysics Department, Faculty of Biology, Moscow State University, Russian Federation
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41
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Heterogeneity in photosystem I fromPisum sativum L. CHINESE SCIENCE BULLETIN-CHINESE 1999. [DOI: 10.1007/bf03182886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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42
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Malkin S, Braun G. The degree of functional separation between the two photosystems in isolated thylakoid membranes deduced from inhibition studies of the imbalance in photoactivities. PHOTOSYNTHESIS RESEARCH 1993; 36:89-94. [PMID: 24318869 DOI: 10.1007/bf00016273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/1992] [Accepted: 01/27/1993] [Indexed: 06/02/2023]
Abstract
In order to examine whether the two photosystems, PS I and PS II, are organized in specific electron transporting pairs, or randomly transport electrons from PS II to PS I, the photosystems imbalance of photoactivities (Emerson enhancement) was measured by modulated fluorimetry under different degrees of PS II inhibition in broken chloroplasts, where the granal structures were preserved by the presence of 5 mM MgCl. The results indicate a lack of any measurable specific functional pairing between individual PS I and PS II, in contrast to a previous research work in leaves (Malkin et al. 1986, Photosynth. Res. 10: 291-296). These results and this discrepancy are further discussed.
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Affiliation(s)
- S Malkin
- Biochemistry Department, The Weizmann Institute of Science, 76100, Rehovot, Israel
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43
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Anderson JM. Cytochrome b 6 f complex: Dynamic molecular organization, function and acclimation. PHOTOSYNTHESIS RESEARCH 1992; 34:341-57. [PMID: 24408831 DOI: 10.1007/bf00029810] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/1992] [Accepted: 06/05/1992] [Indexed: 05/06/2023]
Abstract
The cytochrome b 6 f complex occupies a central position in photosynthetic electron transport and proton translocation by linking PS II to PS I in linear electron flow from water to NADP(+), and around PS I for cyclic electron flow. Cytochrome b 6 f complexes are uniquely located in three membrane domains: the appressed granal membranes, the non-appressed stroma thylakoids and end grana membranes, and also the non-appressed grana margins, in contrast to the marked lateral heterogeneity of the localization of all other thylakoid multiprotein complexes. In addition to its vital role in vectorial electron transfer and proton translocation across the membrane, cytochrome b 6 f complex is also involved in the regulation of balanced light excitation energy distribution between the photosystems, since its redox state governs the activation of LHC II kinase (the kinase that phosphorylates the mobile peripheral fraction of the chlorophyll a/b-proteins of LHC II of PS II). Hence, cytochrome b 6 f complex is the molecular link in the interactive co-regulation of light-harvesting and electron transfer.The importance of a highly dynamic, yet flexible organization of the thylakoid membranes of plants and green algae has been highlighted by the exciting discovery that a lateral reorganization of some cytochrome b 6 f complexes occurs in the state transition mechanism both in vivo and in vitro (Vallon et al. 1991). The lateral redistribution of phosphorylated LHC II from stacked granal membrane regions is accompanied by a concomitant movement of some cytochrome b 6 f complexes from the granal membranes out to the PS I-containing stroma thylakoids. Thus, the dynamic movement of cytochrome b 6 f complex as a multiprotein complex is a molecular mechanism for short-term adaptation to changing light conditions. With the concept of different membrane domains for linear and cyclic electron flow gaining credence, it is thought that linear electron flow occurs in the granal compartments and cyclic electron flow is localised in the stroma thylakoids at non-limiting irradiances. It is postulated that dynamic lateral reversible redistribution of some cytochrome b 6 f complexes are part of the molecular mechanism involved in the regulation of linear electron transfer (ATP and NADPH) and cyclic electron flow (ATP only). Finally, the molecular significance of the marked regulation of cytochrome b 6 f complexes for long-term regulation and optimization of photosynthetic function under varying environmental conditions, particularly light acclimation, is discussed.
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Affiliation(s)
- J M Anderson
- Division of Plant Industry, CSIRO, GPO Box 1600, 2601, Canberra, ACT, Australia
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44
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Braun G, Malkin S. Kinetic relationships between structural changes in the thylakoid membranes and photosystems organization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/s0005-2728(05)80321-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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45
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Biochemical and biophysical properties of thylakoid acyl lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/s0005-2728(09)91002-7] [Citation(s) in RCA: 189] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Energy transfer process during senescence: fluorescence and photoacoustic studies of intact pea leaves. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/s0005-2728(05)80284-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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47
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Tyystjärvi E, Aro EM. Temperature-dependent changes in Photosystem II heterogeneity support a cycle of Photosystem II during photoinhibition. PHOTOSYNTHESIS RESEARCH 1990; 26:109-117. [PMID: 24420463 DOI: 10.1007/bf00047082] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/1989] [Accepted: 06/26/1990] [Indexed: 06/03/2023]
Abstract
High light treatments were given to attached leaves of pumpkin (Cucurbita pepo L.) at room temperature and at 1°C where the diffusion- and enzyme-dependent repair processes of Photosystem II are at a minimum. After treatments, electron transfer activities and fluorescence induction were measured from thylakoids isolated from the treated leaves. When the photoinhibition treatment was given at 1°C, the Photosystem II electron transfer assays that were designed to require electron transfer to the plastoquinone pool showed greater inhibition than electron transfer from H2O to paraphenyl-benzoquinone, which measures all PS II centers. When the light treatment was given at room temperature, electron transfer from H2O to paraphenyl-benzoquinone was inhibited more than whole-chain electron transfer. Variable fluorescence measured in the presence of ferricyanide decreased only during room-temperature treatments. These results suggest that reaction centers of one pool of Photosystem II, non-QB-PS II, replace photoinhibited reaction centers at room temperature, while no replacement occurs at 1°C. A simulation of photoinhibition at 1°C supports this conclusion.
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Affiliation(s)
- E Tyystjärvi
- Department of Biology, University of Turku, SF-20500, Turku, Finland
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48
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Regulation of the imbalance in light excitation between Photosystem II and Photosystem I by cations and by the energized state of the thylakoid membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1990. [DOI: 10.1016/0005-2728(90)90181-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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49
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Davies TG, Thomas H, Rogers LJ. Immunochemical quantification of cytochrome f in leaves of a non-yellowing senescence mutant of Festuca pratensis. PHOTOSYNTHESIS RESEARCH 1990; 24:99-108. [PMID: 24419770 DOI: 10.1007/bf00032649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/1989] [Accepted: 11/01/1989] [Indexed: 06/03/2023]
Abstract
A non-competitive enzyme-linked immunosorbent assay (ELISA) which enables detection of as little as 0.1 ng cytochrome f in leaf extracts has been developed. No evidence for specific or non-specific interference by proteins other than cytochrome f was found. The assay was applied to a comparative study of age-related changes in the cytochrome f content of leaves of Festuca pratensis Huds. cv. Rossa, and a non-yellowing mutant genotype (Bf993) having a lesion in the mechanism responsible for thylakoid membrane disassembly. Cytochrome f in senescent leaves of the latter genotype was found to be present at significantly higher levels than in the wild-type, implying an inability on the part of the mutant to degrade this protein. The results obtained by ELISA were confirmed by antibody probing of Western blots.
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Affiliation(s)
- T G Davies
- Welsh Plant Breeding Station, Cell Biology Department, AFRC Institute for Grassland and Animal Production, Plas Gogerddan, SY23 3EB, Aberystwyth, Dyfed, UK
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50
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Kagan VE, Serbinova EA, Koynova GM, Kitanova SA, Tyurin VA, Stoytchev TS, Quinn PJ, Packer L. Antioxidant action of ubiquinol homologues with different isoprenoid chain length in biomembranes. Free Radic Biol Med 1990; 9:117-26. [PMID: 2227528 DOI: 10.1016/0891-5849(90)90114-x] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ubiquinones (CoQn) are intrinsic lipid components of many membranes. Besides their role in electron-transfer reactions they may act as free radical scavengers, yet their antioxidant function has received relatively little study. The efficiency of ubiquinols of varying isoprenoid chain length (from Q0 to Q10) in preventing (Fe2+ + ascorbate)-dependent or (Fe2+ + NADPH)-dependent lipid peroxidation was investigated in rat liver microsomes and brain synaptosomes and mitochondria. Ubiquinols, the reduced forms of CoQn, possess much greater antioxidant activity than the oxidized ubiquinone forms. In homogenous solution the radical scavenging activity of ubiquinol homologues does not depend on the length of their isoprenoid chain. However in membranes ubiquinols with short isoprenoid chains (Q1-Q4) are much more potent inhibitors of lipid peroxidation than the longer chain homologues (Q5-Q10). It is found that: i) the inhibitory action, that is, antioxidant efficiency of short-chain ubiquinols decreases in order Q1 greater than Q2 greater than Q3 greater than Q4; ii) the antioxidant efficiency of long-chain ubiquinols is only slightly dependent on their concentrations in the order Q5 greater than Q6 greater than Q7 greater than Q8 greater than Q9 greater than Q10 and iii) the antioxidant efficiency of Q0 is markedly less than that of other homologues. Interaction of ubiquinols with oxygen radicals was followed by their effects on luminol-activated chemiluminescence. Ubiquinols Q1-Q4 at 0.1 mM completely inhibit the luminol-activated NADPH-dependent chemiluminescent response of microsomes, while homologues Q6-Q10 exert no effect. In contrast to ubiquinol Q10 (ubiquinone Q10) ubiquinone Q1 synergistically enhances NADPH-dependent regeneration of endogenous vitamin E in microsomes thus providing for higher antioxidant protection against lipid peroxidation. The differences in the antioxidant potency of ubiquinols in membranes are suggested to result from differences in partitioning into membranes, intramembrane mobility and non-uniform distribution of ubiquinols resulting in differing efficiency of interaction with oxygen and lipid radicals as well as different efficiency of ubiquinols in regeneration of endogenous vitamin E.
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Affiliation(s)
- V E Kagan
- Institute of Physiology, Bulgarian Academy of Sciences, Sofia
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