1
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Su-Zhou C, Durand M, Aphalo PJ, Martinez-Abaigar J, Shapiguzov A, Ishihara H, Liu X, Robson TM. Weaker photosynthetic acclimation to fluctuating than to corresponding steady UVB radiation treatments in grapevines. PHYSIOLOGIA PLANTARUM 2024; 176:e14383. [PMID: 38859677 DOI: 10.1111/ppl.14383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 05/17/2024] [Accepted: 05/25/2024] [Indexed: 06/12/2024]
Abstract
The effects of transient increases in UVB radiation on plants are not well known; whether cumulative damage dominates or, alternately, an increase in photoprotection and recovery periods ameliorates any negative effects. We investigated photosynthetic capacity and metabolite accumulation of grapevines (Vitis vinifera Cabernet Sauvignon) in response to UVB fluctuations under four treatments: fluctuating UVB (FUV) and steady UVB radiation (SUV) at similar total biologically effective UVB dose (2.12 and 2.23 kJ m-2 day-1), and their two respective no UVB controls. We found a greater decrease in stomatal conductance under SUV than FUV. There was no decrease in maximum yield of photosystem II (Fv/Fm) or its operational efficiency (ɸPSII) under the two UVB treatments, and Fv/Fm was higher under SUV than FUV. Photosynthetic capacity was enhanced under FUV in the light-limited region of rapid light-response curves but enhanced by SUV in the light-saturated region. Flavonol content was similarly increased by both UVB treatments. We conclude that, while both FUV and SUV effectively stimulate acclimation to UVB radiation at realistic doses, FUV confers weaker acclimation than SUV. This implies that recovery periods between transient increases in UVB radiation reduce UVB acclimation, compared to an equivalent dose of UVB provided continuously. Thus, caution is needed in interpreting the findings of experiments using steady UVB radiation treatments to infer effects in natural environments, as the stimulatory effect of steady UVB is greater than that of the equivalent fluctuating UVB.
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Affiliation(s)
- Chenxing Su-Zhou
- College of Enology, Northwest A&F University, Yangling, Shaanxi, China
- Organismal and Evolutionary Biology (OEB), Viikki Plant Science Centre (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Shaanxi Engineering Research Center for Viti-Viniculture, Yangling, Shaanxi, China
| | - Maxime Durand
- Organismal and Evolutionary Biology (OEB), Viikki Plant Science Centre (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Pedro J Aphalo
- Organismal and Evolutionary Biology (OEB), Viikki Plant Science Centre (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | | | - Alexey Shapiguzov
- Organismal and Evolutionary Biology (OEB), Viikki Plant Science Centre (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Natural Resources Institute Finland (Luke), Production Systems, Finland
| | - Hirofumi Ishihara
- Organismal and Evolutionary Biology (OEB), Viikki Plant Science Centre (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Xu Liu
- College of Enology, Northwest A&F University, Yangling, Shaanxi, China
- Shaanxi Engineering Research Center for Viti-Viniculture, Yangling, Shaanxi, China
| | - T Matthew Robson
- Organismal and Evolutionary Biology (OEB), Viikki Plant Science Centre (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- National School of Forestry, University of Cumbria, Ambleside, UK
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2
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Tikhonov AN. The cytochrome b 6f complex: plastoquinol oxidation and regulation of electron transport in chloroplasts. PHOTOSYNTHESIS RESEARCH 2024; 159:203-227. [PMID: 37369875 DOI: 10.1007/s11120-023-01034-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023]
Abstract
In oxygenic photosynthetic systems, the cytochrome b6f (Cytb6f) complex (plastoquinol:plastocyanin oxidoreductase) is a heart of the hub that provides connectivity between photosystems (PS) II and I. In this review, the structure and function of the Cytb6f complex are briefly outlined, being focused on the mechanisms of a bifurcated (two-electron) oxidation of plastoquinol (PQH2). In plant chloroplasts, under a wide range of experimental conditions (pH and temperature), a diffusion of PQH2 from PSII to the Cytb6f does not limit the intersystem electron transport. The overall rate of PQH2 turnover is determined mainly by the first step of the bifurcated oxidation of PQH2 at the catalytic site Qo, i.e., the reaction of electron transfer from PQH2 to the Fe2S2 cluster of the high-potential Rieske iron-sulfur protein (ISP). This point has been supported by the quantum chemical analysis of PQH2 oxidation within the framework of a model system including the Fe2S2 cluster of the ISP and surrounding amino acids, the low-potential heme b6L, Glu78 and 2,3,5-trimethylbenzoquinol (the tail-less analog of PQH2). Other structure-function relationships and mechanisms of electron transport regulation of oxygenic photosynthesis associated with the Cytb6f complex are briefly outlined: pH-dependent control of the intersystem electron transport and the regulatory balance between the operation of linear and cyclic electron transfer chains.
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Affiliation(s)
- Alexander N Tikhonov
- Department of Biophysics, Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russian Federation, 119991.
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3
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Dziubek D, Poeker L, Siemitkowska B, Graf A, Marino G, Alseekh S, Arrivault S, Fernie AR, Armbruster U, Geigenberger P. NTRC and thioredoxins m1/m2 underpin the light acclimation of plants on proteome and metabolome levels. PLANT PHYSIOLOGY 2024; 194:982-1005. [PMID: 37804523 PMCID: PMC10828201 DOI: 10.1093/plphys/kiad535] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 10/09/2023]
Abstract
During photosynthesis, plants must manage strong fluctuations in light availability on different time scales, leading to long-term acclimation and short-term responses. However, little is known about the regulation and coordination of these processes and the modulators involved. In this study, we used proteomics, metabolomics, and reverse genetics to investigate how different light environmental factors, such as intensity or variability, affect long-term and short-term acclimation responses of Arabidopsis (Arabidopsis thaliana) and the importance of the chloroplast redox network in their regulation. In the wild type, high light, but not fluctuating light, led to large quantitative changes in the proteome and metabolome, accompanied by increased photosynthetic dynamics and plant growth. This finding supports light intensity as a stronger driver for acclimation than variability. Deficiencies in NADPH-thioredoxin reductase C (NTRC) or thioredoxins m1/m2, but not thioredoxin f1, almost completely suppressed the re-engineering of the proteome and metabolome, with both the induction of proteins involved in stress and redox responses and the repression of those involved in cytosolic and plastid protein synthesis and translation being strongly attenuated. Moreover, the correlations of protein or metabolite levels with light intensity were severely disturbed, suggesting a general defect in the light-dependent acclimation response, resulting in impaired photosynthetic dynamics. These results indicate a previously unknown role of NTRC and thioredoxins m1/m2 in modulating light acclimation at proteome and metabolome levels to control dynamic light responses. NTRC, but not thioredoxins m1/m2 or f1, also improves short-term photosynthetic responses by balancing the Calvin-Benson cycle in fluctuating light.
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Affiliation(s)
- Dejan Dziubek
- Fakultät für Biologie, Ludwig-Maximilians-Universität München, Grosshaderner Str. 2-4, 82152 Martinsried, Germany
| | - Louis Poeker
- Fakultät für Biologie, Ludwig-Maximilians-Universität München, Grosshaderner Str. 2-4, 82152 Martinsried, Germany
| | - Beata Siemitkowska
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Alexander Graf
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Giada Marino
- Fakultät für Biologie, Ludwig-Maximilians-Universität München, Grosshaderner Str. 2-4, 82152 Martinsried, Germany
| | - Saleh Alseekh
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
- Departments of Metabolomics and Crop Quantitative Genetics, Center of Plant Systems Biology and Biotechnology, 4000 Plovdiv, Bulgari
| | - Stéphanie Arrivault
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Alisdair R Fernie
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
- Departments of Metabolomics and Crop Quantitative Genetics, Center of Plant Systems Biology and Biotechnology, 4000 Plovdiv, Bulgari
| | - Ute Armbruster
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
- Institute of Molecular Photosynthesis, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
- CEPLAS—Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Peter Geigenberger
- Fakultät für Biologie, Ludwig-Maximilians-Universität München, Grosshaderner Str. 2-4, 82152 Martinsried, Germany
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4
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Calzadilla PI, Song J, Gallois P, Johnson GN. Proximity to Photosystem II is necessary for activation of Plastid Terminal Oxidase (PTOX) for photoprotection. Nat Commun 2024; 15:287. [PMID: 38177155 PMCID: PMC10767095 DOI: 10.1038/s41467-023-44454-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024] Open
Abstract
The Plastid Terminal Oxidase (PTOX) is a chloroplast localized plastoquinone oxygen oxidoreductase suggested to have the potential to act as a photoprotective safety valve for photosynthesis. However, PTOX overexpression in plants has been unsuccessful at inducing photoprotection, and the factors that control its activity remain elusive. Here, we show that significant PTOX activity is induced in response to high light in the model species Eutrema salsugineum and Arabidopsis thaliana. This activation correlates with structural reorganization of the thylakoid membrane. Over-expression of PTOX in mutants of Arabidopsis thaliana perturbed in thylakoid stacking also results in such activity, in contrast to wild type plants with normal granal structure. Further, PTOX activation protects against photoinhibition of Photosystem II and reduces reactive oxygen production under stress conditions. We conclude that structural re-arrangements of the thylakoid membranes, bringing Photosystem II and PTOX into proximity, are both required and sufficient for PTOX to act as a Photosystem II sink and play a role in photoprotection.
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Affiliation(s)
- Pablo Ignacio Calzadilla
- Department of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom
| | - Junliang Song
- Department of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom
| | - Patrick Gallois
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Giles Nicholas Johnson
- Department of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom.
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5
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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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6
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Gollan PJ, Grebe S, Roling L, Grimm B, Spetea C, Aro E. Photosynthetic and transcriptome responses to fluctuating light in Arabidopsis thylakoid ion transport triple mutant. PLANT DIRECT 2023; 7:e534. [PMID: 37886682 PMCID: PMC10598627 DOI: 10.1002/pld3.534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 08/29/2023] [Accepted: 09/14/2023] [Indexed: 10/28/2023]
Abstract
Fluctuating light intensity challenges fluent photosynthetic electron transport in plants, inducing photoprotection while diminishing carbon assimilation and growth, and also influencing photosynthetic signaling for regulation of gene expression. Here, we employed in vivo chlorophyll-a fluorescence and P700 difference absorption measurements to demonstrate the enhancement of photoprotective energy dissipation of both photosystems in wild-type Arabidopsis thaliana after 6 h exposure to fluctuating light as compared with constant light conditions. This acclimation response to fluctuating light was hampered in a triple mutant lacking the thylakoid ion transport proteins KEA3, VCCN1, and CLCe, leading to photoinhibition of photosystem I. Transcriptome analysis revealed upregulation of genes involved in biotic stress and defense responses in both genotypes after exposure to fluctuating as compared with constant light, yet these responses were demonstrated to be largely upregulated in triple mutant already under constant light conditions compared with wild type. The current study illustrates the rapid acclimation of plants to fluctuating light, including photosynthetic, transcriptomic, and metabolic adjustments, and highlights the connection among thylakoid ion transport, photosynthetic energy balance, and cell signaling.
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Affiliation(s)
- Peter J. Gollan
- Department of Life Technologies, Molecular Plant BiologyUniversity of TurkuTurkuFinland
| | - Steffen Grebe
- Department of Life Technologies, Molecular Plant BiologyUniversity of TurkuTurkuFinland
- Present address:
Optics of Photosynthesis Laboratory, Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, Viikki Plant Science Center (ViPS)University of HelsinkiHelsinkiFinland
| | - Lena Roling
- Institute of Biology/Plant PhysiologyHumboldt‐Universität zu BerlinBerlinGermany
| | - Bernhard Grimm
- Institute of Biology/Plant PhysiologyHumboldt‐Universität zu BerlinBerlinGermany
| | - Cornelia Spetea
- Department of Biological and Environmental SciencesUniversity of GothenburgGothenburgSweden
| | - Eva‐Mari Aro
- Department of Life Technologies, Molecular Plant BiologyUniversity of TurkuTurkuFinland
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7
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Natale S, La Rocca N, Battistuzzi M, Morosinotto T, Nardini A, Alboresi A. Structure and function of bark and wood chloroplasts in a drought-tolerant tree (Fraxinus ornus L.). TREE PHYSIOLOGY 2023; 43:893-908. [PMID: 36738252 DOI: 10.1093/treephys/tpad013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 01/31/2023] [Indexed: 06/11/2023]
Abstract
Leaves are the most important photosynthetic organs in most woody plants, but chloroplasts are also found in organs optimized for other functions. However, the actual photosynthetic efficiency of these chloroplasts is still unclear. We analyzed bark and wood chloroplasts of Fraxinus ornus L. saplings. Optical and spectroscopic methods were applied to stem samples and compared with leaves. A sharp light gradient was detected along the stem radial direction, with blue light mainly absorbed by the outer bark, and far-red-enriched light reaching the underlying xylem and pith. Chlorophylls were evident in the xylem rays and the pith and showed an increasing concentration gradient toward the bark. The stem photosynthetic apparatus showed features typical of acclimation to a low-light environment, such as larger grana stacks, lower chlorophyll a/b and photosystem I/II ratios compared with leaves. Despite likely receiving very few photons, wood chloroplasts were photosynthetically active and fully capable of generating a light-dependent electron transport. Our data provide a comprehensive scenario of the functional features of bark and wood chloroplasts in a woody species and suggest that stem photosynthesis is coherently optimized to the prevailing micro-environmental conditions at the bark and wood level.
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Affiliation(s)
- Sara Natale
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, Trieste 34127, Italy
| | - Nicoletta La Rocca
- Department of Biology, University of Padova, Via Ugo Bassi 58B, Padova 35121, Italy
| | - Mariano Battistuzzi
- Department of Biology, University of Padova, Via Ugo Bassi 58B, Padova 35121, Italy
| | - Tomas Morosinotto
- Department of Biology, University of Padova, Via Ugo Bassi 58B, Padova 35121, Italy
| | - Andrea Nardini
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, Trieste 34127, Italy
| | - Alessandro Alboresi
- Department of Biology, University of Padova, Via Ugo Bassi 58B, Padova 35121, Italy
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8
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Flannery SE, Pastorelli F, Emrich‐Mills TZ, Casson SA, Hunter CN, Dickman MJ, Jackson PJ, Johnson MP. STN7 is not essential for developmental acclimation of Arabidopsis to light intensity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 114:1458-1474. [PMID: 36960687 PMCID: PMC10952155 DOI: 10.1111/tpj.16204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 03/12/2023] [Accepted: 03/15/2023] [Indexed: 06/17/2023]
Abstract
Plants respond to changing light intensity in the short term through regulation of light harvesting, electron transfer, and metabolism to mitigate redox stress. A sustained shift in light intensity leads to a long-term acclimation response (LTR). This involves adjustment in the stoichiometry of photosynthetic complexes through de novo synthesis and degradation of specific proteins associated with the thylakoid membrane. The light-harvesting complex II (LHCII) serine/threonine kinase STN7 plays a key role in short-term light harvesting regulation and was also suggested to be crucial to the LTR. Arabidopsis plants lacking STN7 (stn7) shifted to low light experience higher photosystem II (PSII) redox pressure than the wild type or those lacking the cognate phosphatase TAP38 (tap38), while the reverse is true at high light, where tap38 suffers more. In principle, the LTR should allow optimisation of the stoichiometry of photosynthetic complexes to mitigate these effects. We used quantitative label-free proteomics to assess how the relative abundance of photosynthetic proteins varied with growth light intensity in wild-type, stn7, and tap38 plants. All plants were able to adjust photosystem I, LHCII, cytochrome b6 f, and ATP synthase abundance with changing white light intensity, demonstrating neither STN7 nor TAP38 is crucial to the LTR per se. However, stn7 plants grown for several weeks at low light (LL) or moderate light (ML) still showed high PSII redox pressure and correspondingly lower PSII efficiency, CO2 assimilation, and leaf area compared to wild-type and tap38 plants, hence the LTR is unable to fully ameliorate these symptoms. In contrast, under high light growth conditions the mutants and wild type behaved similarly. These data are consistent with the paramount role of STN7-dependent LHCII phosphorylation in tuning PSII redox state for optimal growth in LL and ML conditions.
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Affiliation(s)
- Sarah E. Flannery
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldFirth Court, Western BankSheffieldUK
| | - Federica Pastorelli
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldFirth Court, Western BankSheffieldUK
| | - Thomas Z. Emrich‐Mills
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldFirth Court, Western BankSheffieldUK
| | - Stuart A. Casson
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldFirth Court, Western BankSheffieldUK
| | - C. Neil Hunter
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldFirth Court, Western BankSheffieldUK
| | - Mark J. Dickman
- Department of Chemical and Biological EngineeringUniversity of SheffieldSheffieldUK
| | - Philip J. Jackson
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldFirth Court, Western BankSheffieldUK
- Department of Chemical and Biological EngineeringUniversity of SheffieldSheffieldUK
| | - Matthew P. Johnson
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldFirth Court, Western BankSheffieldUK
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9
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Degen GE, Jackson PJ, Proctor MS, Zoulias N, Casson SA, Johnson MP. High cyclic electron transfer via the PGR5 pathway in the absence of photosynthetic control. PLANT PHYSIOLOGY 2023; 192:370-386. [PMID: 36774530 PMCID: PMC10152662 DOI: 10.1093/plphys/kiad084] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 01/24/2023] [Indexed: 05/03/2023]
Abstract
The light reactions of photosynthesis couple electron and proton transfers across the thylakoid membrane, generating NADPH, and proton motive force (pmf) that powers the endergonic synthesis of ATP by ATP synthase. ATP and NADPH are required for CO2 fixation into carbohydrates by the Calvin-Benson-Bassham cycle. The dominant ΔpH component of the pmf also plays a photoprotective role in regulating photosystem II light harvesting efficiency through nonphotochemical quenching (NPQ) and photosynthetic control via electron transfer from cytochrome b6f (cytb6f) to photosystem I. ΔpH can be adjusted by increasing the proton influx into the thylakoid lumen via upregulation of cyclic electron transfer (CET) or decreasing proton efflux via downregulation of ATP synthase conductivity (gH+). The interplay and relative contributions of these two elements of ΔpH control to photoprotection are not well understood. Here, we showed that an Arabidopsis (Arabidopsis thaliana) ATP synthase mutant hunger for oxygen in photosynthetic transfer reaction 2 (hope2) with 40% higher proton efflux has supercharged CET. Double crosses of hope2 with the CET-deficient proton gradient regulation 5 and ndh-like photosynthetic complex I lines revealed that PROTON GRADIENT REGULATION 5 (PGR5)-dependent CET is the major pathway contributing to higher proton influx. PGR5-dependent CET allowed hope2 to maintain wild-type levels of ΔpH, CO2 fixation and NPQ, however photosynthetic control remained absent and PSI was prone to photoinhibition. Therefore, high CET in the absence of ATP synthase regulation is insufficient for PSI photoprotection.
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Affiliation(s)
- Gustaf E Degen
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Philip J Jackson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 4NL, UK
| | - Matthew S Proctor
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Nicholas Zoulias
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Stuart A Casson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Matthew P Johnson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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10
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Jackson PJ, Hitchcock A, Brindley AA, Dickman MJ, Hunter CN. Absolute quantification of cellular levels of photosynthesis-related proteins in Synechocystis sp. PCC 6803. PHOTOSYNTHESIS RESEARCH 2023; 155:219-245. [PMID: 36542271 PMCID: PMC9958174 DOI: 10.1007/s11120-022-00990-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
Quantifying cellular components is a basic and important step for understanding how a cell works, how it responds to environmental changes, and for re-engineering cells to produce valuable metabolites and increased biomass. We quantified proteins in the model cyanobacterium Synechocystis sp. PCC 6803 given the general importance of cyanobacteria for global photosynthesis, for synthetic biology and biotechnology research, and their ancestral relationship to the chloroplasts of plants. Four mass spectrometry methods were used to quantify cellular components involved in the biosynthesis of chlorophyll, carotenoid and bilin pigments, membrane assembly, the light reactions of photosynthesis, fixation of carbon dioxide and nitrogen, and hydrogen and sulfur metabolism. Components of biosynthetic pathways, such as those for chlorophyll or for photosystem II assembly, range between 1000 and 10,000 copies per cell, but can be tenfold higher for CO2 fixation enzymes. The most abundant subunits are those for photosystem I, with around 100,000 copies per cell, approximately 2 to fivefold higher than for photosystem II and ATP synthase, and 5-20 fold more than for the cytochrome b6f complex. Disparities between numbers of pathway enzymes, between components of electron transfer chains, and between subunits within complexes indicate possible control points for biosynthetic processes, bioenergetic reactions and for the assembly of multisubunit complexes.
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Affiliation(s)
- Philip J Jackson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK.
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK.
| | - Andrew Hitchcock
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Amanda A Brindley
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK
| | - C Neil Hunter
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
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11
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Wu HY, Qiao MY, Zhang YJ, Kang WJ, Ma QH, Gao HY, Zhang WF, Jiang CD. Photosynthetic mechanism of maize yield under fluctuating light environments in the field. PLANT PHYSIOLOGY 2023; 191:957-973. [PMID: 36459464 PMCID: PMC9922410 DOI: 10.1093/plphys/kiac542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
The photosynthetic mechanism of crop yields in fluctuating light environments in the field remains controversial. To further elucidate this mechanism, we conducted field and simulation experiments using maize (Zea mays) plants. Increased planting density enhanced the light fluctuation frequency and reduced the duration of daily high light, as well as the light-saturated photosynthetic rate, biomass, and yield per plant. Further analysis confirmed a highly significant positive correlation between biomass and yield per plant and the duration of photosynthesis related to daily high light. The simulation experiment indicated that the light-saturated photosynthetic rate of maize leaves decreased gradually and considerably when shortening the daily duration of high light. Under an identical duration of high light exposure, increasing the fluctuation frequency decreased the light-saturated photosynthetic rate slightly. Proteomic data also demonstrated that photosynthesis was mainly affected by the duration of high light and not by the light fluctuation frequency. Consequently, the current study proposes that an appropriate duration of daily high light under fluctuating light environments is the key factor for greatly improving photosynthesis. This is a promising mechanism by which the photosynthetic productivity and yield of maize can be enhanced under complex light environments in the field.
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Affiliation(s)
- Han-Yu Wu
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Corps/College of Agronomy, Shihezi University, Shihezi 832003, China
| | - Mei-Yu Qiao
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Ya-Jun Zhang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Wei-Jian Kang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Qing-Hu Ma
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Hui-Yuan Gao
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Wang-Feng Zhang
- Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Corps/College of Agronomy, Shihezi University, Shihezi 832003, China
| | - Chuang-Dao Jiang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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12
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Proteomic Analysis of Proteins Related to Defense Responses in Arabidopsis Plants Transformed with the rolB Oncogene. Int J Mol Sci 2023; 24:ijms24031880. [PMID: 36768198 PMCID: PMC9915171 DOI: 10.3390/ijms24031880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 01/10/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
During Agrobacterium rhizogenes-plant interaction, the rolB gene is transferred into the plant genome and is stably inherited in the plant's offspring. Among the numerous effects of rolB on plant metabolism, including the activation of secondary metabolism, its effect on plant defense systems has not been sufficiently studied. In this work, we performed a proteomic analysis of rolB-expressing Arabidopsis thaliana plants with particular focus on defense proteins. We found a total of 77 overexpressed proteins and 64 underexpressed proteins in rolB-transformed plants using two-dimensional gel electrophoresis and MALDI mass spectrometry. In the rolB-transformed plants, we found a reduced amount of scaffold proteins RACK1A, RACK1B, and RACK1C, which are known as receptors for activated C-kinase 1. The proteomic analysis showed that rolB could suppress the plant immune system by suppressing the RNA-binding proteins GRP7, CP29B, and CP31B, which action are similar to the action of type-III bacterial effectors. At the same time, rolB plants induce the massive biosynthesis of protective proteins VSP1 and VSP2, as well as pathogenesis-related protein PR-4, which are markers of the activated jasmonate pathway. The increased contents of glutathione-S-transferases F6, F2, F10, U19, and DHAR1 and the osmotin-like defense protein OSM34 were found. The defense-associated protein PCaP1, which is required for oligogalacturonide-induced priming and immunity, was upregulated. Moreover, rolB-transformed plants showed the activation of all components of the PYK10 defense complex that is involved in the metabolism of glucosinolates. We hypothesized that various defense systems activated by rolB protect the host plant from competing phytopathogens and created an effective ecological niche for A. rhizogenes. A RolB → RACK1A signaling module was proposed that might exert most of the rolB-mediated effects on plant physiology. Our proteomics data are available via ProteomeXchange with identifier PXD037959.
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Cun Z, Xu XZ, Zhang JY, Shuang SP, Wu HM, An TX, Chen JW. Responses of photosystem to long-term light stress in a typically shade-tolerant species Panax notoginseng. FRONTIERS IN PLANT SCIENCE 2023; 13:1095726. [PMID: 36714733 PMCID: PMC9878349 DOI: 10.3389/fpls.2022.1095726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 12/27/2022] [Indexed: 06/18/2023]
Abstract
Photosynthetic adaptive strategies vary with the growth irradiance. The potential photosynthetic adaptive strategies of shade-tolerant species Panax notoginseng (Burkill) F. H. Chen to long-term high light and low light remains unclear. Photosynthetic performance, photosynthesis-related pigments, leaves anatomical characteristics and antioxidant enzyme activities were comparatively determined in P. notoginseng grown under different light regimes. The thickness of the upper epidermis, palisade tissue, and lower epidermis were declined with increasing growth irradiance. Low-light-grown leaves were declined in transpiration rate (Tr) and stomatal conductance (Cond), but intercellular CO2 concentration (C i) and net photosynthesis rate (P n) had opposite trends. The maximum photo-oxidation P 700 + (P m) was greatly reduced in 29.8% full sunlight (FL) plants; The maximum quantum yield of photosystem II (F v/F m) in 0.2% FL plants was significantly lowest. Electron transport, thermal dissipation, and the effective quantum yield of PSI [Y(I)] and PSII [Y(II)] were declined in low-light-grown plants compared with high-light-grown P. notoginseng. The minimum value of non-regulated energy dissipation of PSII [Y(NO)] was recorded in 0.2% FL P. notoginseng. OJIP kinetic curve showed that relative variable fluorescence at J-phase (V J) and the ratio of variable fluorescent F K occupying the F J-F O amplitude (W k) were significantly increased in 0.2% FL plants. However, the increase in W k was lower than the increase in V J. In conclusion, PSI photoinhibition is the underlying sensitivity of the typically shade-tolerant species P. notoginseng to high light, and the photodamage to PSII acceptor side might cause the typically shade-tolerant plants to be unsuitable for long-term low light stress.
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Affiliation(s)
- Zhu Cun
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Xiang-Zeng Xu
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
- Research Center for Collection and Utilization of Tropical Crop Resources, Yunnan Institute of Tropical Crops, Xishuangbanna, China
| | - Jin-Yan Zhang
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Sheng-Pu Shuang
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Hong-Min Wu
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
| | - Tong-Xin An
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
| | - Jun-Wen Chen
- College of Agronomy & Biotechnology, Yunnan Agricultural University, Kunming, China
- Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China
- National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwestern China, Yunnan Agricultural University, Kunming, China
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Krynická V, Skotnicová P, Jackson PJ, Barnett S, Yu J, Wysocka A, Kaňa R, Dickman MJ, Nixon PJ, Hunter CN, Komenda J. FtsH4 protease controls biogenesis of the PSII complex by dual regulation of high light-inducible proteins. PLANT COMMUNICATIONS 2023; 4:100502. [PMID: 36463410 PMCID: PMC9860182 DOI: 10.1016/j.xplc.2022.100502] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 11/11/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
FtsH proteases are membrane-embedded proteolytic complexes important for protein quality control and regulation of various physiological processes in bacteria, mitochondria, and chloroplasts. Like most cyanobacteria, the model species Synechocystis sp. PCC 6803 contains four FtsH homologs, FtsH1-FtsH4. FtsH1-FtsH3 form two hetero-oligomeric complexes, FtsH1/3 and FtsH2/3, which play a pivotal role in acclimation to nutrient deficiency and photosystem II quality control, respectively. FtsH4 differs from the other three homologs by the formation of a homo-oligomeric complex, and together with Arabidopsis thaliana AtFtsH7/9 orthologs, it has been assigned to another phylogenetic group of unknown function. Our results exclude the possibility that Synechocystis FtsH4 structurally or functionally substitutes for the missing or non-functional FtsH2 subunit in the FtsH2/3 complex. Instead, we demonstrate that FtsH4 is involved in the biogenesis of photosystem II by dual regulation of high light-inducible proteins (Hlips). FtsH4 positively regulates expression of Hlips shortly after high light exposure but is also responsible for Hlip removal under conditions when their elevated levels are no longer needed. We provide experimental support for Hlips as proteolytic substrates of FtsH4. Fluorescent labeling of FtsH4 enabled us to assess its localization using advanced microscopic techniques. Results show that FtsH4 complexes are concentrated in well-defined membrane regions at the inner and outer periphery of the thylakoid system. Based on the identification of proteins that co-purified with the tagged FtsH4, we speculate that FtsH4 concentrates in special compartments in which the biogenesis of photosynthetic complexes takes place.
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Affiliation(s)
- Vendula Krynická
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic.
| | - Petra Skotnicová
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic
| | - Philip J Jackson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK; Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, UK
| | - Samuel Barnett
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Jianfeng Yu
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, South Kensington Campus, Imperial College London, London SW7 2AZ, UK
| | - Anna Wysocka
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic; Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
| | - Radek Kaňa
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, UK
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, South Kensington Campus, Imperial College London, London SW7 2AZ, UK
| | - C Neil Hunter
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Josef Komenda
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic
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15
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von Bismarck T, Korkmaz K, Ruß J, Skurk K, Kaiser E, Correa Galvis V, Cruz JA, Strand DD, Köhl K, Eirich J, Finkemeier I, Jahns P, Kramer DM, Armbruster U. Light acclimation interacts with thylakoid ion transport to govern the dynamics of photosynthesis in Arabidopsis. THE NEW PHYTOLOGIST 2023; 237:160-176. [PMID: 36378135 DOI: 10.1111/nph.18534] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 09/27/2022] [Indexed: 06/16/2023]
Abstract
Understanding photosynthesis in natural, dynamic light environments requires knowledge of long-term acclimation, short-term responses, and their mechanistic interactions. To approach the latter, we systematically determined and characterized light-environmental effects on thylakoid ion transport-mediated short-term responses during light fluctuations. For this, Arabidopsis thaliana wild-type and mutants of the Cl- channel VCCN1 and the K+ exchange antiporter KEA3 were grown under eight different light environments and characterized for photosynthesis-associated parameters and factors in steady state and during light fluctuations. For a detailed characterization of selected light conditions, we monitored ion flux dynamics at unprecedented high temporal resolution by a modified spectroscopy approach. Our analyses reveal that daily light intensity sculpts photosynthetic capacity as a main acclimatory driver with positive and negative effects on the function of KEA3 and VCCN1 during high-light phases, respectively. Fluctuations in light intensity boost the accumulation of the photoprotective pigment zeaxanthin (Zx). We show that KEA3 suppresses Zx accumulation during the day, which together with its direct proton transport activity accelerates photosynthetic transition to lower light intensities. In summary, both light-environment factors, intensity and variability, modulate the function of thylakoid ion transport in dynamic photosynthesis with distinct effects on lumen pH, Zx accumulation, photoprotection, and photosynthetic efficiency.
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Affiliation(s)
| | - Kübra Korkmaz
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Jeremy Ruß
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Kira Skurk
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Elias Kaiser
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | | | - Jeffrey A Cruz
- DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Deserah D Strand
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Karin Köhl
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
| | - Jürgen Eirich
- Plant Physiology, Institute of Plant Biology and Biotechnology, University of Münster, 48149, Münster, Germany
| | - Iris Finkemeier
- Plant Physiology, Institute of Plant Biology and Biotechnology, University of Münster, 48149, Münster, Germany
| | - Peter Jahns
- Plant Biochemistry, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany
| | - David M Kramer
- DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Ute Armbruster
- Max Planck Institute of Molecular Plant Physiology, 14476, Potsdam, Germany
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Cryo-EM structures of light-harvesting 2 complexes from Rhodopseudomonas palustris reveal the molecular origin of absorption tuning. Proc Natl Acad Sci U S A 2022; 119:e2210109119. [PMID: 36251992 PMCID: PMC9618040 DOI: 10.1073/pnas.2210109119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The light-harvesting (LH) complexes of phototrophic bacteria absorb solar energy for photosynthesis, and it is important to understand how the protein components influence the way bound pigments absorb light. We studied the LH2 complexes of Rhodopseudomonas palustris, which are encoded by a multigene family. Various combinations of LH2 genes were deleted, yielding strains that assemble only one of the four types of LH2. Following purification, the structures of four LH2 complexes were determined by cryogenic electron microscopy, revealing a basic nonameric ring structure comprising nine αβ-polypeptide pairs. An additional hitherto unknown polypeptide, γ, was found in each structure that binds six further bacteriochlorophylls. Comparison of these different structures shows how nature tunes their ability to absorb different wavelengths of light. The genomes of some purple photosynthetic bacteria contain a multigene puc family encoding a series of α- and β-polypeptides that together form a heterogeneous antenna of light-harvesting 2 (LH2) complexes. To unravel this complexity, we generated four sets of puc deletion mutants in Rhodopseudomonas palustris, each encoding a single type of pucBA gene pair and enabling the purification of complexes designated as PucA-LH2, PucB-LH2, PucD-LH2, and PucE-LH2. The structures of all four purified LH2 complexes were determined by cryogenic electron microscopy (cryo-EM) at resolutions ranging from 2.7 to 3.6 Å. Uniquely, each of these complexes contains a hitherto unknown polypeptide, γ, that forms an extended undulating ribbon that lies in the plane of the membrane and that encloses six of the nine LH2 αβ-subunits. The γ-subunit, which is located near to the cytoplasmic side of the complex, breaks the C9 symmetry of the LH2 complex and binds six extra bacteriochlorophylls (BChls) that enhance the 800-nm absorption of each complex. The structures show that all four complexes have two complete rings of BChls, conferring absorption bands centered at 800 and 850 nm on the PucA-LH2, PucB-LH2, and PucE-LH2 complexes, but, unusually, the PucD-LH2 antenna has only a single strong near-infared (NIR) absorption peak at 803 nm. Comparison of the cryo-EM structures of these LH2 complexes reveals altered patterns of hydrogen bonds between LH2 αβ-side chains and the bacteriochlorin rings, further emphasizing the major role that H bonds play in spectral tuning of bacterial antenna complexes.
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17
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Lempiäinen T, Rintamäki E, Aro E, Tikkanen M. Plants acclimate to Photosystem I photoinhibition by readjusting the photosynthetic machinery. PLANT, CELL & ENVIRONMENT 2022; 45:2954-2971. [PMID: 35916195 PMCID: PMC9546127 DOI: 10.1111/pce.14400] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/14/2022] [Accepted: 07/15/2022] [Indexed: 05/12/2023]
Abstract
Photosynthetic light reactions require strict regulation under dynamic environmental conditions. Still, depending on environmental constraints, photoinhibition of Photosystem (PSII) or PSI occurs frequently. Repair of photodamaged PSI, in sharp contrast to that of PSII, is extremely slow and leads to a functional imbalance between the photosystems. Slow PSI recovery prompted us to take advantage of the PSI-specific photoinhibition treatment and investigate whether the imbalance between functional PSII and PSI leads to acclimation of photosynthesis to PSI-limited conditions, either by short-term or long-term acclimation mechanisms as tested immediately after the photoinhibition treatment or after 24 h recovery in growth conditions, respectively. Short-term acclimation mechanisms were induced directly upon inhibition, including thylakoid protein phosphorylation that redirects excitation energy to PSI as well as changes in the feedback regulation of photosynthesis, which relaxed photosynthetic control and excitation energy quenching. Longer-term acclimation comprised reprogramming of the stromal redox system and an increase in ATP synthase and Cytochrome b6 f abundance. Acclimation to PSI-limited conditions restored the CO2 assimilation capacity of plants without major PSI repair. Response to PSI inhibition demonstrates that plants efficiently acclimate to changes occurring in the photosynthetic apparatus, which is likely a crucial component in plant acclimation to adverse environmental conditions.
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Affiliation(s)
- Tapio Lempiäinen
- Molecular Plant Biology, Department of Life TechnologiesUniversity of TurkuTurkuFinland
| | - Eevi Rintamäki
- Molecular Plant Biology, Department of Life TechnologiesUniversity of TurkuTurkuFinland
| | - Eva‐Mari Aro
- Molecular Plant Biology, Department of Life TechnologiesUniversity of TurkuTurkuFinland
| | - Mikko Tikkanen
- Molecular Plant Biology, Department of Life TechnologiesUniversity of TurkuTurkuFinland
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The Eucalyptus grandis chloroplast proteome: Seasonal variations in leaf development. PLoS One 2022; 17:e0265134. [PMID: 36048873 PMCID: PMC9436043 DOI: 10.1371/journal.pone.0265134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 08/18/2022] [Indexed: 11/26/2022] Open
Abstract
Chloroplast metabolism is very sensitive to environmental fluctuations and is intimately related to plant leaf development. Characterization of the chloroplast proteome dynamics can contribute to a better understanding on plant adaptation to different climate scenarios and leaf development processes. Herein, we carried out a discovery-driven analysis of the Eucalyptus grandis chloroplast proteome during leaf maturation and throughout different seasons of the year. The chloroplast proteome from young leaves differed the most from all assessed samples. Most upregulated proteins identified in mature and young leaves were those related to catabolic-redox signaling and biogenesis processes, respectively. Seasonal dynamics revealed unique proteome features in the fall and spring periods. The most abundant chloroplast protein in humid (wet) seasons (spring and summer) was a small subunit of RuBisCO, while in the dry periods (fall and winter) the proteins that showed the most pronounced accumulation were associated with photo-oxidative damage, Calvin cycle, shikimate pathway, and detoxification. Our investigation of the chloroplast proteome dynamics during leaf development revealed significant alterations in relation to the maturation event. Our findings also suggest that transition seasons induced the most pronounced chloroplast proteome changes over the year. This study contributes to a more comprehensive understanding on the subcellular mechanisms that lead to plant leaf adaptation and ultimately gives more insights into Eucalyptus grandis phenology.
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Suslichenko IS, Trubitsin BV, Vershubskii AV, Tikhonov AN. The noninvasive monitoring of the redox status of photosynthetic electron transport chains in Hibiscus rosa-sinensis and Tradescantia leaves. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 185:233-243. [PMID: 35716433 DOI: 10.1016/j.plaphy.2022.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 05/13/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
We present an approach to the noninvasive determination of the electron capacity of the intersystem pool of electron carriers in chloroplasts in situ. As apt experimental models, we used the leaves of Hibiscus rosa-sinensis and Tradescantia species. Electron paramagnetic resonance and optical response of P700 (the primary electron donor in Photosystem I) were applied to measuring electron transport in chloroplasts. Electron capacities of the intersystem electron transport chain (ETC) were determined from redox transients of P700 upon chromatic transitions (white light → far-red light). During the induction period, we observed the nonmonotonic changes in the number of electron equivalents in the intersystem ETC per P700 (parameter Q). In Hibiscus rosa-sinensis, the light-induced rise of Q from ≈2.5 (in the dark) to Q ≈ 12 was followed by its decrease to Q ≈ 6. The data obtained are discussed in the context of pH-dependent regulation of electron transport in chloroplasts, which provides the well-balanced operation of the intersystem ETC. The decay of Q is explained by the attenuation of Photosystem II activity due to the lumen acidification and the acceleration of plastoquinol re-oxidation as a result of the Calvin-Benson cycle activation. Our computer model of electron and proton transport coupled to ATP synthesis in chloroplasts was used to analyze the up and down feedbacks responsible for pH-dependent regulation of electron transport in chloroplasts. The procedures introduced here may be important for subsequent works aimed at defining the plastoquinone participation in regulation of photosynthetic processes in chloroplasts in situ.
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Affiliation(s)
- Igor S Suslichenko
- Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Boris V Trubitsin
- Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, Russia
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20
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Ksas B, Alric J, Caffarri S, Havaux M. Plastoquinone homeostasis in plant acclimation to light intensity. PHOTOSYNTHESIS RESEARCH 2022; 152:43-54. [PMID: 35000138 DOI: 10.1007/s11120-021-00889-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/29/2021] [Indexed: 05/08/2023]
Abstract
Arabidopsis plants were grown from seeds at different photon flux densities (PFDs) of white light ranging from 65 to 800 µmol photons m-2 s-1. Increasing PFD brought about a marked accumulation of plastoquinone (PQ) in leaves. However, the thylakoid photoactive PQ pool, estimated to about 700 pmol mg-1 leaf dry weight, was independent of PFD; PQ accumulation in high light mostly occurred in the photochemically non-active pool (plastoglobules, chloroplast envelopes) which represented up to 75% of total PQ. The amounts of PSII reaction center (on a leaf dry weight basis) also were little affected by PFD during growth, leading to a constant PQ/PSII ratio at all PFDs. Boosting PQ biosynthesis by overexpression of a solanesyl diphosphate-synthesizing enzyme strongly enhanced the PQ levels, particularly at high PFDs. Again, this accumulation occurred exclusively in the non-photoactive PQ pool. Mutational suppression of the plastoglobular ABC1K1 kinase led to a selective reduction of the thylakoid PQ pool size to ca. 400 pmol mg-1 in a large range of PFDs, which was associated with a restriction of the photosynthetic electron flow. Our results show that photosynthetic acclimation to light intensity does not involve modulation of the thylakoid PQ pool size or the amounts of PSII reaction centers. There appears to be a fixed amount of PQ molecules for optimal interaction with PSII and efficient photosynthesis, with the extra PQ molecules being stored outside the thylakoid membranes, implying a tight regulation of PQ distribution within the chloroplasts.
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Affiliation(s)
- Brigitte Ksas
- Aix-Marseille University, CEA, CNRS UMR7265, BIAM, City of Energies, CEA Cadarache, 13115, Saint-Paul-lez-Durance, France
| | - Jean Alric
- Aix-Marseille University, CEA, CNRS UMR7265, BIAM, City of Energies, CEA Cadarache, 13115, Saint-Paul-lez-Durance, France
| | - Stefano Caffarri
- Aix-Marseille University, CEA, CNRS UMR7265, BIAM, 13009, Marseille, France
| | - Michel Havaux
- Aix-Marseille University, CEA, CNRS UMR7265, BIAM, City of Energies, CEA Cadarache, 13115, Saint-Paul-lez-Durance, France.
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MacGregor-Chatwin C, Nürnberg DJ, Jackson PJ, Vasilev C, Hitchcock A, Ho MY, Shen G, Gisriel CJ, Wood WH, Mahbub M, Selinger VM, Johnson MP, Dickman MJ, Rutherford AW, Bryant DA, Hunter CN. Changes in supramolecular organization of cyanobacterial thylakoid membrane complexes in response to far-red light photoacclimation. SCIENCE ADVANCES 2022; 8:eabj4437. [PMID: 35138895 PMCID: PMC8827656 DOI: 10.1126/sciadv.abj4437] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
Cyanobacteria are ubiquitous in nature and have developed numerous strategies that allow them to live in a diverse range of environments. Certain cyanobacteria synthesize chlorophylls d and f to acclimate to niches enriched in far-red light (FRL) and incorporate paralogous photosynthetic proteins into their photosynthetic apparatus in a process called FRL-induced photoacclimation (FaRLiP). We characterized the macromolecular changes involved in FRL-driven photosynthesis and used atomic force microscopy to examine the supramolecular organization of photosystem I associated with FaRLiP in three cyanobacterial species. Mass spectrometry showed the changes in the proteome of Chroococcidiopsis thermalis PCC 7203 that accompany FaRLiP. Fluorescence lifetime imaging microscopy and electron microscopy reveal an altered cellular distribution of photosystem complexes and illustrate the cell-to-cell variability of the FaRLiP response.
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Affiliation(s)
| | - Dennis J. Nürnberg
- Department of Life Sciences, Imperial College London, London, UK
- Physics Department, Freie Universität Berlin, Berlin, Germany
| | - Philip J. Jackson
- School of Biosciences, University of Sheffield, Sheffield, UK
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | | | | | - Ming-Yang Ho
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Christopher J. Gisriel
- Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, AZ, USA
| | | | - Moontaha Mahbub
- Department of Life Sciences, Imperial College London, London, UK
| | | | | | - Mark J. Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | | | - Donald A. Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - C. Neil Hunter
- School of Biosciences, University of Sheffield, Sheffield, UK
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22
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Yu L, Fujiwara K, Matsuda R. Estimating Light Acclimation Parameters of Cucumber Leaves Using Time-Weighted Averages of Daily Photosynthetic Photon Flux Density. FRONTIERS IN PLANT SCIENCE 2022; 12:809046. [PMID: 35211135 PMCID: PMC8860900 DOI: 10.3389/fpls.2021.809046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
Leaves acclimate to day-to-day fluctuating levels of photosynthetic photon flux density (PPFD) by adjusting their morphological and physiological parameters. Accurate estimation of these parameters under day-to-day fluctuating PPFD conditions benefits crop growth modeling and light environment management in greenhouses, although it remains challenging. We quantified the relationships between day-to-day PPFD changes over 6 days and light acclimation parameters for cucumber seedling leaves, including leaf mass per area (LMA), chlorophyll (Chl) a/b ratio, maximum net photosynthetic rate (P nmax), maximum rate of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (V cmax), and maximum rate of electron transport (J max). The last two parameters reflect the capacity of the photosynthetic partial reactions. We built linear regression models of these parameters based on average or time-weighted averages of daily PPFDs. For time-weighted averages of daily PPFDs, the influence of daily PPFD was given a specific weight. We employed three types of functions to calculate this weight, including linear, quadratic, and sigmoid derivative types. We then determined the trend of weights that estimated each parameter most accurately. Moreover, we introduced saturating functions to calibrate the average or time-weighted averages of daily PPFDs, considering that light acclimation parameters are usually saturated under high PPFDs. We found that time-weighted average PPFDs, in which recent PPFD levels had larger weights than earlier levels, better estimated LMA than average PPFDs. This suggests that recent PPFDs contribute more to LMA than earlier PPFDs. Except for the Chl a/b ratio, the average PPFDs estimated P nmax, V cmax, and J max with acceptable accuracy. In contrast, time-weighted averages of daily PPFDs did not improve the estimation accuracy of these four parameters, possibly due to their low response rates and plasticity. Calibrating functions generally improved estimation of Chl a/b ratio, V cmax, and J max because of their saturating tendencies under high PPFDs. Our findings provide a reasonable approach to quantifying the extent to which the leaves acclimate to day-to-day fluctuating PPFDs, especially the extent of LMA.
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23
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Colpo A, Baldisserotto C, Pancaldi S, Sabia A, Ferroni L. Photosystem II photoinhibition and photoprotection in a lycophyte, Selaginella martensii. PHYSIOLOGIA PLANTARUM 2022; 174:e13604. [PMID: 34811759 PMCID: PMC9300044 DOI: 10.1111/ppl.13604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 11/09/2021] [Accepted: 11/19/2021] [Indexed: 05/13/2023]
Abstract
The Lycophyte Selaginella martensii efficiently acclimates to diverse light environments, from deep shade to full sunlight. The plant does not modulate the abundance of the Light Harvesting Complex II, mostly found as a free trimer, and does not alter the maximum capacity of thermal dissipation (NPQ). Nevertheless, the photoprotection is expected to be modulatable upon long-term light acclimation to preserve the photosystems (PSII, PSI). The effects of long-term light acclimation on PSII photoprotection were investigated using the chlorophyll fluorometric method known as "photochemical quenching measured in the dark" (qPd ). Singularly high-qPd values at relatively low irradiance suggest a heterogeneous antenna system (PSII antenna uncoupling). The extent of antenna uncoupling largely depends on the light regime, reaching the highest value in sun-acclimated plants. In parallel, the photoprotective NPQ (pNPQ) increased from deep-shade to high-light grown plants. It is proposed that the differences in the long-term modulation in the photoprotective capacity are proportional to the amount of uncoupled LHCII. In deep-shade plants, the inconsistency between invariable maximum NPQ and lower pNPQ is attributed to the thermal dissipation occurring in the PSII core.
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Affiliation(s)
- Andrea Colpo
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
| | | | - Simonetta Pancaldi
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
| | - Alessandra Sabia
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
| | - Lorenzo Ferroni
- Department of Environmental and Prevention SciencesUniversity of FerraraFerrara
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24
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Cryo-EM structure of the dimeric Rhodobacter sphaeroides RC-LH1 core complex at 2.9 Å: the structural basis for dimerisation. Biochem J 2021; 478:3923-3937. [PMID: 34622934 PMCID: PMC8652583 DOI: 10.1042/bcj20210696] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/07/2021] [Accepted: 10/07/2021] [Indexed: 11/23/2022]
Abstract
The dimeric reaction centre light-harvesting 1 (RC-LH1) core complex of Rhodobacter sphaeroides converts absorbed light energy to a charge separation, and then it reduces a quinone electron and proton acceptor to a quinol. The angle between the two monomers imposes a bent configuration on the dimer complex, which exerts a major influence on the curvature of the membrane vesicles, known as chromatophores, where the light-driven photosynthetic reactions take place. To investigate the dimerisation interface between two RC-LH1 monomers, we determined the cryogenic electron microscopy structure of the dimeric complex at 2.9 Å resolution. The structure shows that each monomer consists of a central RC partly enclosed by a 14-subunit LH1 ring held in an open state by PufX and protein-Y polypeptides, thus enabling quinones to enter and leave the complex. Two monomers are brought together through N-terminal interactions between PufX polypeptides on the cytoplasmic side of the complex, augmented by two novel transmembrane polypeptides, designated protein-Z, that bind to the outer faces of the two central LH1 β polypeptides. The precise fit at the dimer interface, enabled by PufX and protein-Z, by C-terminal interactions between opposing LH1 αβ subunits, and by a series of interactions with a bound sulfoquinovosyl diacylglycerol lipid, bring together each monomer creating an S-shaped array of 28 bacteriochlorophylls. The seamless join between the two sets of LH1 bacteriochlorophylls provides a path for excitation energy absorbed by one half of the complex to migrate across the dimer interface to the other half.
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25
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Sheng X, Liu Z, Kim E, Minagawa J. Plant and Algal PSII-LHCII Supercomplexes: Structure, Evolution and Energy Transfer. PLANT & CELL PHYSIOLOGY 2021; 62:1108-1120. [PMID: 34038564 DOI: 10.1093/pcp/pcab072] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/19/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Photosynthesis is the process conducted by plants and algae to capture photons and store their energy in chemical forms. The light-harvesting, excitation transfer, charge separation and electron transfer in photosystem II (PSII) are the critical initial reactions of photosynthesis and thereby largely determine its overall efficiency. In this review, we outline the rapidly accumulating knowledge about the architectures and assemblies of plant and green algal PSII-light harvesting complex II (LHCII) supercomplexes, with a particular focus on new insights provided by the recent high-resolution cryo-electron microscopy map of the supercomplexes from a green alga Chlamydomonas reinhardtii. We make pair-wise comparative analyses between the supercomplexes from plants and green algae to gain insights about the evolution of the PSII-LHCII supercomplexes involving the peripheral small PSII subunits that might have been acquired during the evolution and about the energy transfer pathways that define their light-harvesting and photoprotective properties.
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Affiliation(s)
- Xin Sheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Eunchul Kim
- Division of Environmental Photobiology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Jun Minagawa
- Division of Environmental Photobiology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
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26
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Cryo-EM structure of the monomeric Rhodobacter sphaeroides RC-LH1 core complex at 2.5 Å. Biochem J 2021; 478:3775-3790. [PMID: 34590677 PMCID: PMC8589327 DOI: 10.1042/bcj20210631] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 09/22/2021] [Accepted: 09/30/2021] [Indexed: 12/02/2022]
Abstract
Reaction centre light-harvesting 1 (RC–LH1) complexes are the essential components of bacterial photosynthesis. The membrane-intrinsic LH1 complex absorbs light and the energy migrates to an enclosed RC where a succession of electron and proton transfers conserves the energy as a quinol, which is exported to the cytochrome bc1 complex. In some RC–LH1 variants quinols can diffuse through small pores in a fully circular, 16-subunit LH1 ring, while in others missing LH1 subunits create a gap for quinol export. We used cryogenic electron microscopy to obtain a 2.5 Å resolution structure of one such RC–LH1, a monomeric complex from Rhodobacter sphaeroides. The structure shows that the RC is partly enclosed by a 14-subunit LH1 ring in which each αβ heterodimer binds two bacteriochlorophylls and, unusually for currently reported complexes, two carotenoids rather than one. Although the extra carotenoids confer an advantage in terms of photoprotection and light harvesting, they could impede passage of quinones through small, transient pores in the LH1 ring, necessitating a mechanism to create a dedicated quinone channel. The structure shows that two transmembrane proteins play a part in stabilising an open ring structure; one of these components, the PufX polypeptide, is augmented by a hitherto undescribed protein subunit we designate as protein-Y, which lies against the transmembrane regions of the thirteenth and fourteenth LH1α polypeptides. Protein-Y prevents LH1 subunits 11–14 adjacent to the RC QB site from bending inwards towards the RC and, with PufX preventing complete encirclement of the RC, this pair of polypeptides ensures unhindered quinone diffusion.
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27
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Mazur R, Mostowska A, Kowalewska Ł. How to Measure Grana - Ultrastructural Features of Thylakoid Membranes of Plant Chloroplasts. FRONTIERS IN PLANT SCIENCE 2021; 12:756009. [PMID: 34691132 PMCID: PMC8527009 DOI: 10.3389/fpls.2021.756009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 09/09/2021] [Indexed: 06/11/2023]
Abstract
Granum is a basic structural unit of the thylakoid membrane network of plant chloroplasts. It is composed of multiple flattened membranes forming a stacked arrangement of a cylindrical shape. Grana membranes are composed of lipids and tightly packed pigment-protein complexes whose primary role is the catalysis of photosynthetic light reactions. These membranes are highly dynamic structures capable of adapting to changing environmental conditions by fine-tuning photochemical efficiency, manifested by the structural reorganization of grana stacks. Due to a nanometer length scale of the structural granum features, the application of high-resolution electron microscopic techniques is essential for a detailed analysis of the granum architecture. This mini-review overviews recent approaches to quantitative grana structure analyses from electron microscopy data, highlighting the basic manual measurements and semi-automated workflows. We outline and define structural parameters used by different authors, for instance, granum height and diameter, thylakoid thickness, end-membrane length, Stacking Repeat Distance, and Granum Lateral Irregularity. This article also presents insights into efficient and effective measurements of grana stacks visualized on 2D micrographs. The information on how to correctly interpret obtained data, taking into account the 3D nature of grana stacks projected onto 2D space of electron micrograph, is also given. Grana ultrastructural observations reveal key features of this intriguing membrane arrangement, broadening our knowledge of the thylakoid network's remarkable plasticity.
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Affiliation(s)
- Radosław Mazur
- Department of Metabolic Regulation, Institute of Biochemistry, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Agnieszka Mostowska
- Department of Plant Anatomy and Cytology, Institute of Plant Experimental Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Łucja Kowalewska
- Department of Plant Anatomy and Cytology, Institute of Plant Experimental Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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28
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Flannery SE, Pastorelli F, Wood WHJ, Hunter CN, Dickman MJ, Jackson PJ, Johnson MP. Comparative proteomics of thylakoids from Arabidopsis grown in laboratory and field conditions. PLANT DIRECT 2021; 5:e355. [PMID: 34712896 PMCID: PMC8528093 DOI: 10.1002/pld3.355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/21/2021] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
Compared to controlled laboratory conditions, plant growth in the field is rarely optimal since it is frequently challenged by large fluctuations in light and temperature which lower the efficiency of photosynthesis and lead to photo-oxidative stress. Plants grown under natural conditions therefore place an increased onus on the regulatory mechanisms that protect and repair the delicate photosynthetic machinery. Yet, the exact changes in thylakoid proteome composition which allow plants to acclimate to the natural environment remain largely unexplored. Here, we use quantitative label-free proteomics to demonstrate that field-grown Arabidopsis plants incorporate aspects of both the low and high light acclimation strategies previously observed in laboratory-grown plants. Field plants showed increases in the relative abundance of ATP synthase, cytochrome b 6 f, ferredoxin-NADP+ reductases (FNR1 and FNR2) and their membrane tethers TIC62 and TROL, thylakoid architecture proteins CURT1A, CURT1B, RIQ1, and RIQ2, the minor monomeric antenna complex CP29.3, rapidly-relaxing non-photochemical quenching (qE)-related proteins PSBS and VDE, the photosystem II (PSII) repair machinery and the cyclic electron transfer complexes NDH, PGRL1B, and PGR5, in addition to decreases in the amounts of LHCII trimers composed of LHCB1.1, LHCB1.2, LHCB1.4, and LHCB2 proteins and CP29.2, all features typical of a laboratory high light acclimation response. Conversely, field plants also showed increases in the abundance of light harvesting proteins LHCB1.3 and CP29.1, zeaxanthin epoxidase (ZEP) and the slowly-relaxing non-photochemical quenching (qI)-related protein LCNP, changes previously associated with a laboratory low light acclimation response. Field plants also showed distinct changes to the proteome including the appearance of stress-related proteins ELIP1 and ELIP2 and changes to proteins that are largely invariant under laboratory conditions such as state transition related proteins STN7 and TAP38. We discuss the significance of these alterations in the thylakoid proteome considering the unique set of challenges faced by plants growing under natural conditions.
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Affiliation(s)
- Sarah E. Flannery
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldSheffieldUK
| | - Federica Pastorelli
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldSheffieldUK
| | - William H. J. Wood
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldSheffieldUK
| | - C. Neil Hunter
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldSheffieldUK
| | - Mark J. Dickman
- Department of Chemical and Biological EngineeringUniversity of SheffieldSheffieldUK
| | - Philip J. Jackson
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldSheffieldUK
- Department of Chemical and Biological EngineeringUniversity of SheffieldSheffieldUK
| | - Matthew P. Johnson
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldSheffieldUK
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29
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Chadee A, Alber NA, Dahal K, Vanlerberghe GC. The Complementary Roles of Chloroplast Cyclic Electron Transport and Mitochondrial Alternative Oxidase to Ensure Photosynthetic Performance. FRONTIERS IN PLANT SCIENCE 2021; 12:748204. [PMID: 34650584 PMCID: PMC8505746 DOI: 10.3389/fpls.2021.748204] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/30/2021] [Indexed: 05/29/2023]
Abstract
Chloroplasts use light energy and a linear electron transport (LET) pathway for the coupled generation of NADPH and ATP. It is widely accepted that the production ratio of ATP to NADPH is usually less than required to fulfill the energetic needs of the chloroplast. Left uncorrected, this would quickly result in an over-reduction of the stromal pyridine nucleotide pool (i.e., high NADPH/NADP+ ratio) and under-energization of the stromal adenine nucleotide pool (i.e., low ATP/ADP ratio). These imbalances could cause metabolic bottlenecks, as well as increased generation of damaging reactive oxygen species. Chloroplast cyclic electron transport (CET) and the chloroplast malate valve could each act to prevent stromal over-reduction, albeit in distinct ways. CET avoids the NADPH production associated with LET, while the malate valve consumes the NADPH associated with LET. CET could operate by one of two different pathways, depending upon the chloroplast ATP demand. The NADH dehydrogenase-like pathway yields a higher ATP return per electron flux than the pathway involving PROTON GRADIENT REGULATION5 (PGR5) and PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE1 (PGRL1). Similarly, the malate valve could couple with one of two different mitochondrial electron transport pathways, depending upon the cytosolic ATP demand. The cytochrome pathway yields a higher ATP return per electron flux than the alternative oxidase (AOX) pathway. In both Arabidopsis thaliana and Chlamydomonas reinhardtii, PGR5/PGRL1 pathway mutants have increased amounts of AOX, suggesting complementary roles for these two lesser-ATP yielding mechanisms of preventing stromal over-reduction. These two pathways may become most relevant under environmental stress conditions that lower the ATP demands for carbon fixation and carbohydrate export.
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Affiliation(s)
- Avesh Chadee
- Department of Biological Sciences, and Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, Canada
| | - Nicole A. Alber
- Department of Biological Sciences, and Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, Canada
| | - Keshav Dahal
- Fredericton Research and Development Centre, Agriculture and Agri-Food Canada, Fredericton, NB, Canada
| | - Greg C. Vanlerberghe
- Department of Biological Sciences, and Department of Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, Canada
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30
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Anderson CM, Mattoon EM, Zhang N, Becker E, McHargue W, Yang J, Patel D, Dautermann O, McAdam SAM, Tarin T, Pathak S, Avenson TJ, Berry J, Braud M, Niyogi KK, Wilson M, Nusinow DA, Vargas R, Czymmek KJ, Eveland AL, Zhang R. High light and temperature reduce photosynthetic efficiency through different mechanisms in the C 4 model Setaria viridis. Commun Biol 2021; 4:1092. [PMID: 34531541 PMCID: PMC8446033 DOI: 10.1038/s42003-021-02576-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 08/03/2021] [Indexed: 11/09/2022] Open
Abstract
C4 plants frequently experience high light and high temperature conditions in the field, which reduce growth and yield. However, the mechanisms underlying these stress responses in C4 plants have been under-explored, especially the coordination between mesophyll (M) and bundle sheath (BS) cells. We investigated how the C4 model plant Setaria viridis responded to a four-hour high light or high temperature treatment at photosynthetic, transcriptomic, and ultrastructural levels. Although we observed a comparable reduction of photosynthetic efficiency in high light or high temperature treated leaves, detailed analysis of multi-level responses revealed important differences in key pathways and M/BS specificity responding to high light and high temperature. We provide a systematic analysis of high light and high temperature responses in S. viridis, reveal different acclimation strategies to these two stresses in C4 plants, discover unique light/temperature responses in C4 plants in comparison to C3 plants, and identify potential targets to improve abiotic stress tolerance in C4 crops.
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Affiliation(s)
| | - Erin M Mattoon
- Donald Danforth Plant Science Center, St. Louis, MO, USA.,Plant and Microbial Biosciences Program, Division of Biology and Biomedical Sciences, Washington University in Saint Louis, St. Louis, MO, USA
| | - Ningning Zhang
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | - Eric Becker
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | | | - Jiani Yang
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | - Dhruv Patel
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Oliver Dautermann
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Scott A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Tonantzin Tarin
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA.,Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Sunita Pathak
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | - Tom J Avenson
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Jeffrey Berry
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | - Maxwell Braud
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | - Krishna K Niyogi
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.,Howard Hughes Medical Institute, Berkeley, CA, USA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | | | - Rodrigo Vargas
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA
| | - Kirk J Czymmek
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | | | - Ru Zhang
- Donald Danforth Plant Science Center, St. Louis, MO, USA.
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31
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Terashima I, Matsuo M, Suzuki Y, Yamori W, Kono M. Photosystem I in low light-grown leaves of Alocasia odora, a shade-tolerant plant, is resistant to fluctuating light-induced photoinhibition. PHOTOSYNTHESIS RESEARCH 2021; 149:69-82. [PMID: 33817762 DOI: 10.1007/s11120-021-00832-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/22/2021] [Indexed: 05/15/2023]
Abstract
When intact green leaves are exposed to the fluctuating light, in which high light (HL) and low light (LL) alternate, photosystem I (PSI) is readily damaged. This PSI inhibition is mostly alleviated by the addition of far-red (FR) light. Here, we grew Alocasia odora, a shade-tolerant species, at several light levels and examined their photosynthetic traits in relation to the fluctuating light-induced PSI inhibition. We found that, even in the absence of FR, PSI in LL-grown leaves was resistant to the fluctuating light. LL leaves showed higher chlorophyll (Chl) contents on leaf area basis, lower Chl a/b ratios, lower cytochrome f/P700 ratios, and lower PSII/PSI excitation ratios assessed by the 77 K fluorescence. Also, P700 in the HL phase of the fluctuating light was more oxidized. The results of the regression analyses of the PSI photoinhibition to these traits indicate that the lower electron flow rate to P700 and more excitation energy transfer to PSI protect PSI in LL-grown leaves. Both of these contribute oxidization of P700 to the efficient quencher form P700+. These features may be common in LL-grown shade-tolerant species, which are often exposed to strong sunflecks in their natural habitats.
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Affiliation(s)
- Ichiro Terashima
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Mitsutoshi Matsuo
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yoshihiro Suzuki
- Department of Biological Sciences, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka-City, Kanagawa, 259-1293, Japan
| | - Wataru Yamori
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
- Institute for Sustainable Agro-ecosystem Services (ISAS), Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Midori-cho, Nishitokyo-City, Tokyo, 188-0002, Japan
| | - Masaru Kono
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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