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Lübben MK, Klingl A, Nickelsen J, Ostermeier M. CLEM, a universal tool for analyzing structural organization in thylakoid membranes. PHYSIOLOGIA PLANTARUM 2024; 176:e14417. [PMID: 38945684 DOI: 10.1111/ppl.14417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 05/15/2024] [Indexed: 07/02/2024]
Abstract
Chlorophyll (Chl) plays a crucial role in photosynthesis, functioning as a photosensitizer. As an integral component of this process, energy absorbed by this pigment is partly emitted as red fluorescence. This signal can be readily imaged by fluorescence microscopy and provides a visualization of photosynthetic activity. However, due to limited resolution, signals cannot be assigned to specific subcellular/organellar membrane structures. By correlating fluorescence micrographs with transmission electron microscopy, researchers can identify sub-cellular compartments and membranes, enabling the monitoring of Chl distribution within thylakoid membrane substructures in cyanobacteria, algae, and higher plant single cells. Here, we describe a simple and effective protocol for correlative light-electron microscopy (CLEM) based on the autofluorescence of Chl and demonstrate its application to selected photosynthetic model organisms. Our findings illustrate the potential of this technique to identify areas of high Chl concentration and photochemical activity, such as grana regions in vascular plants, by mapping stacked thylakoids.
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Affiliation(s)
- Maximilian K Lübben
- Department of Molecular Plant Science, LMU Munich, Planegg-Martinsried, Germany
| | - Andreas Klingl
- Plant Development, LMU Munich, Planegg-Martinsried, Germany
| | - Jörg Nickelsen
- Department of Molecular Plant Science, LMU Munich, Planegg-Martinsried, Germany
| | - Matthias Ostermeier
- Department of Molecular Plant Science, LMU Munich, Planegg-Martinsried, Germany
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2
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Garty Y, Bussi Y, Levin-Zaidman S, Shimoni E, Kirchhoff H, Charuvi D, Nevo R, Reich Z. Thylakoid membrane stacking controls electron transport mode during the dark-to-light transition by adjusting the distances between PSI and PSII. NATURE PLANTS 2024; 10:512-524. [PMID: 38396112 DOI: 10.1038/s41477-024-01628-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 01/23/2024] [Indexed: 02/25/2024]
Abstract
The balance between linear electron transport (LET) and cyclic electron transport (CET) plays an essential role in plant adaptation and protection against photo-induced damage. This balance is largely maintained by phosphorylation-driven alterations in the PSII-LHCII assembly and thylakoid membrane stacking. During the dark-to-light transition, plants shift this balance from CET, which prevails to prevent overreduction of the electron transport chain and consequent photo-induced damage, towards LET, which enables efficient CO2 assimilation and biomass production. Using freeze-fracture cryo-scanning electron microscopy and transmission electron microscopy of Arabidopsis leaves, we reveal unique membrane regions possessing characteristics of both stacked and unstacked regions of the thylakoid network that form during this transition. A notable consequence of the morphological attributes of these regions, which we refer to as 'stacked thylakoid doublets', is an overall increase in the proximity and connectivity of the two photosystems (PSI and PSII) that drive LET. This, in turn, reduces diffusion distances and barriers for the mobile carriers that transfer electrons between the two PSs, thereby maximizing LET and optimizing the plant's ability to utilize light energy. The mechanics described here for the shift between CET and LET during the dark-to-light transition are probably also used during chromatic adaptation mediated by state transitions.
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Affiliation(s)
- Yuval Garty
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Yuval Bussi
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Smadar Levin-Zaidman
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Helmut Kirchhoff
- Institute of Biological Chemistry, Washington State University, Pullman, WA, USA
| | - Dana Charuvi
- Institute of Plant Sciences, Agricultural Research Organization, Volcani Institute, Rishon LeZion, Israel
| | - Reinat Nevo
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Ziv Reich
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
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3
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Manna P, Hoffmann M, Davies T, Richardson KH, Johnson MP, Schlau-Cohen GS. Energetic driving force for LHCII clustering in plant membranes. SCIENCE ADVANCES 2023; 9:eadj0807. [PMID: 38134273 PMCID: PMC10745693 DOI: 10.1126/sciadv.adj0807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/21/2023] [Indexed: 12/24/2023]
Abstract
Plants capture and convert solar energy in a complex network of membrane proteins. Under high light, the luminal pH drops and induces a reorganization of the protein network, particularly clustering of the major light-harvesting complex (LHCII). While the structures of the network have been resolved in exquisite detail, the thermodynamics that control the assembly and reorganization had not been determined, largely because the interaction energies of membrane proteins have been inaccessible. Here, we describe a method to quantify these energies and its application to LHCII. Using single-molecule measurements, LHCII proteoliposomes, and statistical thermodynamic modeling, we quantified the LHCII-LHCII interaction energy as ~-5 kBT at neutral pH and at least -7 kBT at acidic pH. These values revealed an enthalpic thermodynamic driving force behind LHCII clustering. Collectively, this work captures the interactions that drive the organization of membrane protein networks from the perspective of equilibrium statistical thermodynamics, which has a long and rich tradition in biology.
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Affiliation(s)
- Premashis Manna
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Madeline Hoffmann
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Thomas Davies
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | | | - Matthew P. Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
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4
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Colpo A, Molinari A, Boldrini P, Živčak M, Brestič M, Demaria S, Baldisserotto C, Pancaldi S, Ferroni L. Thylakoid membrane appression in the giant chloroplast of Selaginella martensii Spring: A lycophyte challenges grana paradigms in shade-adapted species. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 336:111833. [PMID: 37595894 DOI: 10.1016/j.plantsci.2023.111833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 07/17/2023] [Accepted: 08/15/2023] [Indexed: 08/20/2023]
Abstract
In vascular plants, the thylakoid architecture is dominated by the highly structured multiple membrane layers known as grana. The structural diversity of the thylakoid system among plant species is mainly determined by the adaptation to the growth light regime, according to a paradigm stating that shade-tolerant species are featured by a high membrane extension with an enhanced number of thylakoid layers per granum. In this study, the thylakoid system was analysed in Selaginella martensii Spring, a shade-adapted rainforest species belonging to lycophytes, a diminutive plant lineage, sister clade of all other vascular plants (euphyllophytes, including ferns and seed plants). The species is characterized by giant cup-shaped chloroplasts in the upper epidermis and, quantitatively less important, disk-shaped chloroplasts in the mesophyll and lower epidermis. The study aimed at the quantitative assessment of the thylakoid appression exploiting a combination of complementary methods, including electron microscopy, selective thylakoid solubilisation, electron paramagnetic resonance, and simultaneous analysis of fast chlorophyll a fluorescence and P700 redox state. With a chlorophyll a/b ratio of 2.6 and PSI/PSII ratio of 0.31, the plant confirmed two typical hallmarks of shade-adaptation. The morphometric analysis of electron micrographs revealed a 33% fraction of non-appressed thylakoid domains. However, contrasting with the structural paradigm of thylakoid shade-adaptation in angiosperms, S. martensii privileges the increase in the granum diameter in place of the increase in the number of layers building the granum. The very wide grana diameter, 727 nm on average, largely overcame the threshold of 500 nm currently hypothesized to allow an effective diffusion of long-range electron carriers. The fraction of non-appressed membranes based on the selective solubilisation of thylakoids with digitonin was 26%, lower than the morphometric determination, indicating the presence of non-appressed domains inaccessible to the detergent, most probably because of the high three-dimensional complexity of the thylakoid system in S. martensii. Particularly, strong irregularity of grana stacks is determined by assembling thylakoid layers of variable width that tend to slide apart from each other as the number of stacked layers increases.
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Affiliation(s)
- Andrea Colpo
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121 Ferrara, Italy
| | - Alessandra Molinari
- Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Paola Boldrini
- Center of Electron Microscopy, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Marek Živčak
- Department of Plant Physiology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture, A. Hlinku 2, Nitra, 949 76, Slovak Republic
| | - Marian Brestič
- Department of Plant Physiology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture, A. Hlinku 2, Nitra, 949 76, Slovak Republic
| | - Sara Demaria
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121 Ferrara, Italy
| | - Costanza Baldisserotto
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121 Ferrara, Italy
| | - Simonetta Pancaldi
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121 Ferrara, Italy
| | - Lorenzo Ferroni
- Department of Environmental and Prevention Sciences, University of Ferrara, Corso Ercole I d'Este 32, 44121 Ferrara, Italy.
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Paweł R, Aleksandra U, Elżbieta R. Enzymatic kinetics of photosystem II with DCBQ as a substrate in extended Michaelis-Menten model. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2023; 247:112780. [PMID: 37678075 DOI: 10.1016/j.jphotobiol.2023.112780] [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: 06/13/2023] [Revised: 08/17/2023] [Accepted: 08/24/2023] [Indexed: 09/09/2023]
Abstract
This study aimed to examine enzymatic kinetics of photosystem II (PSII) of maize mesophyll chloroplasts using the artificial electron acceptor 2,6-dichloro-1,4-benzoquinone (DCBQ) as a substrate. We extended Michealis-Menten kinetics model assuming that DCBQ can accept electrons from PSII in two ways: from a QB directly or from QA by docking in the QB site. We used a Clark oxygen electrode for measuring the PSII activity, depending on the concentration of DCBQ. We found that: [1] DCBQ acts as an electron acceptor or [2] as an inhibitor for PSII. At a concentration < 0.2 mM, DCBQ accepted electrons from the QB at a rate of 889 electrons/s, while at >> 0.2 mM it replaced QB following which the activity decreased to zero. DCBQ located in the QB also increased the affinity of the substrate to PSII. We determined the kinetic parameters for the chloroplasts of plants growing under high and low light intensity, to change thylakoid stacking and thus the rate of electron transport. The parameter KmB, which is a measure of the affinity of DCBQ to PSII, showed quantitative changes based on light intensity, while K was proportional to the size of the plastoquinone pool. We believe that our model can be applied as a tool to study "State transitions" and induced changes in grana stacking in plants exposed to various stresses, which will facilitate the regulation of electron transfer pathways through an appropriate balance between linear and cyclic electron transport.
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Affiliation(s)
- Rogowski Paweł
- Department of Molecular Plant Physiology, Institute of Environmental Biology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Urban Aleksandra
- Department of Molecular Plant Physiology, Institute of Environmental Biology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Romanowska Elżbieta
- Department of Molecular Plant Physiology, Institute of Environmental Biology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
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6
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Liu XL, Hu YY, Li K, Chen MQ, Wang P. Reconstituted LH2 in multilayer membranes induced by poly-L-lysine: structure of supramolecular and electronic states. ARAB J CHEM 2023. [DOI: 10.1016/j.arabjc.2023.104600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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7
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Zhao Y, Peng X, Wang D, Zhang H, Xin Q, Wu M, Xu X, Sun F, Xing Z, Wang L, Yu P, Xie J, Li J, Tan H, Ding C, Li J. Chloroplast-inspired Scaffold for Infected Bone Defect Therapy: Towards Stable Photothermal Properties and Self-Defensive Functionality. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2204535. [PMID: 36109177 PMCID: PMC9631053 DOI: 10.1002/advs.202204535] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Indexed: 06/02/2023]
Abstract
Bone implant-associated infections induced by bacteria frequently result in repair failure and threaten the health of patients. Although black phosphorus (BP) material with superior photothermal conversion ability is booming in the treatment of bone disease, the development of BP-based bone scaffolds with excellent photothermal stability and antibacterial properties simultaneously remains a challenge. In nature, chloroplasts cannot only convert light into chemical energy, but also hold a protective and defensive envelope membrane. Inspired by this, a self-defensive bone scaffold with stable photothermal property is developed for infected bone defect therapy. Similar to thylakoid and stroma lamella in chloroplasts, BP is integrated with chitosan and polycaprolactone fiber networks. The mussel-inspired polydopamine multifunctional "envelope membrane" wrapped above not only strengthens the photothermal stability of BP-based scaffolds, but also realizes the in situ anchoring of silver nanoparticles. Bacteria-triggered infection of femur defects in vivo can be commendably inhibited at the early stage via these chloroplast-inspired implants, which then effectively promotes endogenous repair of the defect area under mild hyperthermia induced by near-infrared irradiation. This chloroplast-inspired strategy shows outstanding performance for infected bone defect therapy and provides a reference for the functionality of other biomedical materials.
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Affiliation(s)
- Yao Zhao
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Xu Peng
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
- Experimental and Research Animal InstituteSichuan UniversityChengdu610065China
| | - Dingqian Wang
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Hongbo Zhang
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Qiangwei Xin
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Mingzhen Wu
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Xiaoyang Xu
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Fan Sun
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Zeyuan Xing
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Luning Wang
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Peng Yu
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Jing Xie
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Jiehua Li
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Hong Tan
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Chunmei Ding
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Jianshu Li
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
- State Key Laboratory of Oral DiseasesWest China Hospital of StomatologyMed‐X Center for MaterialsSichuan UniversityChengdu610041China
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8
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Gu L, Grodzinski B, Han J, Marie T, Zhang Y, Song YC, Sun Y. Granal thylakoid structure and function: explaining an enduring mystery of higher plants. THE NEW PHYTOLOGIST 2022; 236:319-329. [PMID: 35832001 PMCID: PMC9805053 DOI: 10.1111/nph.18371] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 07/07/2022] [Indexed: 05/11/2023]
Abstract
In higher plants, photosystems II and I are found in grana stacks and unstacked stroma lamellae, respectively. To connect them, electron carriers negotiate tortuous multi-media paths and are subject to macromolecular blocking. Why does evolution select an apparently unnecessary, inefficient bipartition? Here we systematically explain this perplexing phenomenon. We propose that grana stacks, acting like bellows in accordions, increase the degree of ultrastructural control on photosynthesis through thylakoid swelling/shrinking induced by osmotic water fluxes. This control coordinates with variations in stomatal conductance and the turgor of guard cells, which act like an accordion's air button. Thylakoid ultrastructural dynamics regulate macromolecular blocking/collision probability, direct diffusional pathlengths, division of function of Cytochrome b6 f complex between linear and cyclic electron transport, luminal pH via osmotic water fluxes, and the separation of pH dynamics between granal and lamellar lumens in response to environmental variations. With the two functionally asymmetrical photosystems located distantly from each other, the ultrastructural control, nonphotochemical quenching, and carbon-reaction feedbacks maximally cooperate to balance electron transport with gas exchange, provide homeostasis in fluctuating light environments, and protect photosystems in drought. Grana stacks represent a dry/high irradiance adaptation of photosynthetic machinery to improve fitness in challenging land environments. Our theory unifies many well-known but seemingly unconnected phenomena of thylakoid structure and function in higher plants.
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Affiliation(s)
- Lianhong Gu
- Environmental Sciences Division and Climate Change Science InstituteOak Ridge National LaboratoryOak RidgeTN37831USA
| | - Bernard Grodzinski
- Department of Plant AgricultureUniversity of GuelphGuelphONN1G 2W1Canada
| | - Jimei Han
- School of Integrative Plant ScienceCornell UniversityIthacaNY14853USA
| | - Telesphore Marie
- Department of Plant AgricultureUniversity of GuelphGuelphONN1G 2W1Canada
| | | | - Yang C. Song
- Department of Hydrology and Atmospheric SciencesUniversity of ArizonaTucsonAZ85721USA
| | - Ying Sun
- School of Integrative Plant ScienceCornell UniversityIthacaNY14853USA
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9
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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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10
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Bukhanov E, Shabanov AV, Volochaev MN, Pyatina SA. The Role of Periodic Structures in Light Harvesting. PLANTS 2021; 10:plants10091967. [PMID: 34579499 PMCID: PMC8473174 DOI: 10.3390/plants10091967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/08/2021] [Accepted: 09/17/2021] [Indexed: 11/29/2022]
Abstract
The features of light propagation in plant leaves depend on the long-period ordering in chloroplasts and the spectral characteristics of pigments. This work demonstrates a method of determining the hidden ordered structure. Transmission spectra have been determined using transfer matrix method. A band gap was found in the visible spectral range. The effective refractive index and dispersion in the absorption spectrum area of chlorophyll were taken into account to show that the density of photon states increases, while the spectrum shifts towards the wavelength range of effective photosynthesis.
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Affiliation(s)
- Eugene Bukhanov
- Kirensky Institute of Physics FRC «KSC of SB RAS», Academgorodok str. 50/12, 660036 Krasnoyarsk, Russia; (A.V.S.); (M.N.V.)
- Federal Research Center «KSC of SB RAS», Academgorodok str. 50, 660036 Krasnoyarsk, Russia;
- Correspondence: ; Tel.: +7-913-554-3030
| | - Alexandr V. Shabanov
- Kirensky Institute of Physics FRC «KSC of SB RAS», Academgorodok str. 50/12, 660036 Krasnoyarsk, Russia; (A.V.S.); (M.N.V.)
| | - Mikhail N. Volochaev
- Kirensky Institute of Physics FRC «KSC of SB RAS», Academgorodok str. 50/12, 660036 Krasnoyarsk, Russia; (A.V.S.); (M.N.V.)
| | - Svetlana A. Pyatina
- Federal Research Center «KSC of SB RAS», Academgorodok str. 50, 660036 Krasnoyarsk, Russia;
- Institute of Fundamental Biology and Biotechnology, Siberian Federal University, 79 Svobodnyi av., 660041 Krasnoyarsk, Russia
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11
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Karlický V, Kmecová Materová Z, Kurasová I, Nezval J, Štroch M, Garab G, Špunda V. Accumulation of geranylgeranylated chlorophylls in the pigment-protein complexes of Arabidopsis thaliana acclimated to green light: effects on the organization of light-harvesting complex II and photosystem II functions. PHOTOSYNTHESIS RESEARCH 2021; 149:233-252. [PMID: 33948813 PMCID: PMC8382614 DOI: 10.1007/s11120-021-00827-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
Light quality significantly influences plant metabolism, growth and development. Recently, we have demonstrated that leaves of barley and other plant species grown under monochromatic green light (500-590 nm) accumulated a large pool of chlorophyll a (Chl a) intermediates with incomplete hydrogenation of their phytyl chains. In this work, we studied accumulation of these geranylgeranylated Chls a and b in pigment-protein complexes (PPCs) of Arabidopsis plants acclimated to green light and their structural-functional consequences on the photosynthetic apparatus. We found that geranylgeranylated Chls are present in all major PPCs, although their presence was more pronounced in light-harvesting complex II (LHCII) and less prominent in supercomplexes of photosystem II (PSII). Accumulation of geranylgeranylated Chls hampered the formation of PSII and PSI super- and megacomplexes in the thylakoid membranes as well as their assembly into chiral macrodomains; it also lowered the temperature stability of the PPCs, especially that of LHCII trimers, which led to their monomerization and an anomaly in the photoprotective mechanism of non-photochemical quenching. Role of geranylgeranylated Chls in adverse effects on photosynthetic apparatus of plants acclimated to green light is discussed.
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Affiliation(s)
- Václav Karlický
- Department of Physics, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic.
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic.
| | - Zuzana Kmecová Materová
- Department of Physics, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic
| | - Irena Kurasová
- Department of Physics, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic
| | - Jakub Nezval
- Department of Physics, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic
| | - Michal Štroch
- Department of Physics, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic
| | - Győző Garab
- Department of Physics, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic.
- Biological Research Center, Institute of Plant Biology, Temesvári körút 62, 6726, Szeged, Hungary.
| | - Vladimír Špunda
- Department of Physics, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00, Ostrava, Czech Republic.
- Global Change Research Institute, Czech Academy of Sciences, Bělidla 986/4a, 603 00, Brno, Czech Republic.
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12
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Szabó M, Zavafer A. Photoinhibition, photo-ecophysiology, and biophysics, a special issue in honor of Wah Soon Chow. PHOTOSYNTHESIS RESEARCH 2021; 149:1-3. [PMID: 34338942 DOI: 10.1007/s11120-021-00865-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- Milán Szabó
- Institute of Plant Biology, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Szeged, Hungary.
- Climate Change Cluster, University of Technology Sydney, Ultimo, 2007, Australia.
| | - Alonso Zavafer
- Research School of Biology, Australian National University, Canberra, 2600, Australia.
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Saucedo-García M, González-Córdova CD, Ponce-Pineda IG, Cano-Ramírez D, Romero-Colín FM, Arroyo-Pérez EE, King-Díaz B, Zavafer A, Gavilanes-Ruíz M. Effects of MPK3 and MPK6 kinases on the chloroplast architecture and function induced by cold acclimation in Arabidopsis. PHOTOSYNTHESIS RESEARCH 2021; 149:201-212. [PMID: 34132948 DOI: 10.1007/s11120-021-00852-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 05/21/2021] [Indexed: 06/12/2023]
Abstract
Exposure to low, non-freezing temperatures develops freezing tolerance in many plant species. Such process is called cold acclimation. Molecular changes undergone during cold acclimation are orchestrated by signalling networks including MAP kinases. Structure and function of chloroplasts are affected by low temperatures. The aim of this work was to study how the MAP kinases MPK3 and MPK6 are involved in the chloroplast performance upon a long period of cold acclimation. We used Arabidopsis thaliana wild type and mpk3 and mpk6 mutants. Adult plants were acclimated during 7 days at 4 °C and then measurements of PSII performance and chloroplast ultrastructure were carried out. Only the mpk6 acclimated plants showed a high freezing sensitivity. No differences in the PSII function were observed in the plants from the three genotypes exposed to non-acclimated or acclimated conditions. The acclimation of wild-type plants produced severe alterations in the ultrastructure of chloroplast and thylakoids, which was more accentuated in the mpk plants. However, only the mpk6 mutant was unable to internalize the damaged chloroplasts into the vacuole. These results indicate that cold acclimation induces alterations in the chloroplast architecture leading to preserve an optimal performance of PSII. MPK3 and MPK6 are necessary to regulate these morphological changes, but besides, MPK6 is needed to the vacuolization of the damaged chloroplasts, suggesting a role in the chloroplast recycling during cold acclimation. The latter could be quite relevant, since it could explain why this mutant is the only one showing an extremely low freezing tolerance.
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Affiliation(s)
- Mariana Saucedo-García
- Instituto de Ciencias Agropecuarias, Universidad Autónoma del Estado de Hidalgo, Tulancingo, Hidalgo, México
| | - Carla D González-Córdova
- Dpto. de Bioquímica, Conjunto E. Facultad de Química, Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria Universitaria, Coyoacán, 04510, México City, México
| | - I Giordano Ponce-Pineda
- Dpto. de Bioquímica, Conjunto E. Facultad de Química, Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria Universitaria, Coyoacán, 04510, México City, México
| | - Dora Cano-Ramírez
- Dpto. de Bioquímica, Conjunto E. Facultad de Química, Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria Universitaria, Coyoacán, 04510, México City, México
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB3 0LJ, UK
| | - Fernanda M Romero-Colín
- Dpto. de Bioquímica, Conjunto E. Facultad de Química, Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria Universitaria, Coyoacán, 04510, México City, México
| | - Erik E Arroyo-Pérez
- Dpto. de Bioquímica, Conjunto E. Facultad de Química, Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria Universitaria, Coyoacán, 04510, México City, México
| | - Beatriz King-Díaz
- Dpto. de Bioquímica, Conjunto E. Facultad de Química, Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria Universitaria, Coyoacán, 04510, México City, México
| | - Alonso Zavafer
- Research School of Biology, the Australian National University, Canberra, ACT, 2600, Australia
- Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, 2001, Australia
| | - Marina Gavilanes-Ruíz
- Dpto. de Bioquímica, Conjunto E. Facultad de Química, Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria Universitaria, Coyoacán, 04510, México City, México.
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14
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Pashayeva A, Wu G, Huseynova I, Lee CH, Zulfugarov IS. Role of Thylakoid Protein Phosphorylation in Energy-Dependent Quenching of Chlorophyll Fluorescence in Rice Plants. Int J Mol Sci 2021; 22:ijms22157978. [PMID: 34360743 PMCID: PMC8347447 DOI: 10.3390/ijms22157978] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/18/2021] [Accepted: 07/23/2021] [Indexed: 11/16/2022] Open
Abstract
Under natural environments, light quality and quantity are extremely varied. To respond and acclimate to such changes, plants have developed a multiplicity of molecular regulatory mechanisms. Non-photochemical quenching of chlorophyll fluorescence (NPQ) and thylakoid protein phosphorylation are two mechanisms that protect vascular plants. To clarify the role of thylakoid protein phosphorylation in energy-dependent quenching of chlorophyll fluorescence (qE) in rice plants, we used a direct Western blot assay after BN-PAGE to detect all phosphoproteins by P-Thr antibody as well as by P-Lhcb1 and P-Lhcb2 antibodies. Isolated thylakoids in either the dark- or the light-adapted state from wild type (WT) and PsbS-KO rice plants were used for this approach to detect light-dependent interactions between PsbS, PSII, and LHCII proteins. We observed that the bands corresponding to the phosphorylated Lhcb1 and Lhcb2 as well as the other phosphorylated proteins were enhanced in the PsbS-KO mutant after illumination. The qE relaxation became slower in WT plants after 10 min HL treatment, which correlated with Lhcb1 and Lhcb2 protein phosphorylation in the LHCII trimers under the same experimental conditions. Thus, we concluded that light-induced phosphorylation of PSII core and Lhcb1/Lhcb2 proteins is enhanced in rice PsbS-KO plants which might be due to more reactive-oxygen-species production in this mutant.
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Affiliation(s)
- Aynura Pashayeva
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev Str., Baku AZ 1073, Azerbaijan; (A.P.); (I.H.)
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 46241, Korea;
| | - Guangxi Wu
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 46241, Korea;
| | - Irada Huseynova
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev Str., Baku AZ 1073, Azerbaijan; (A.P.); (I.H.)
| | - Choon-Hwan Lee
- Department of Integrated Biological Science, Department of Molecular Biology, Pusan National University, Busan 46241, Korea;
- Correspondence: (C.-H.L.); or (I.S.Z.)
| | - Ismayil S. Zulfugarov
- Institute of Molecular Biology and Biotechnologies, Azerbaijan National Academy of Sciences, 11 Izzat Nabiyev Str., Baku AZ 1073, Azerbaijan; (A.P.); (I.H.)
- Correspondence: (C.-H.L.); or (I.S.Z.)
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15
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Kramer M, Rodriguez-Heredia M, Saccon F, Mosebach L, Twachtmann M, Krieger-Liszkay A, Duffy C, Knell RJ, Finazzi G, Hanke GT. Regulation of photosynthetic electron flow on dark to light transition by ferredoxin:NADP(H) oxidoreductase interactions. eLife 2021; 10:56088. [PMID: 33685582 PMCID: PMC7984839 DOI: 10.7554/elife.56088] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 02/25/2021] [Indexed: 01/12/2023] Open
Abstract
During photosynthesis, electron transport is necessary for carbon assimilation and must be regulated to minimize free radical damage. There is a longstanding controversy over the role of a critical enzyme in this process (ferredoxin:NADP(H) oxidoreductase, or FNR), and in particular its location within chloroplasts. Here we use immunogold labelling to prove that FNR previously assigned as soluble is in fact membrane associated. We combined this technique with a genetic approach in the model plant Arabidopsis to show that the distribution of this enzyme between different membrane regions depends on its interaction with specific tether proteins. We further demonstrate a correlation between the interaction of FNR with different proteins and the activity of alternative photosynthetic electron transport pathways. This supports a role for FNR location in regulating photosynthetic electron flow during the transition from dark to light.
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Affiliation(s)
- Manuela Kramer
- School of Biochemistry and Chemistry, Queen Mary University of London, London, United Kingdom.,Department of Plant Physiology, Faculty of Biology and Chemistry, University of Osnabrück, Osnabrück, Germany
| | | | - Francesco Saccon
- School of Biochemistry and Chemistry, Queen Mary University of London, London, United Kingdom
| | - Laura Mosebach
- Institute of Plant Biology and Biotechnology, University of Münster, Münster, Germany
| | - Manuel Twachtmann
- Department of Plant Physiology, Faculty of Biology and Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Anja Krieger-Liszkay
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Paris, France
| | - Chris Duffy
- School of Biochemistry and Chemistry, Queen Mary University of London, London, United Kingdom
| | - Robert J Knell
- School of Biochemistry and Chemistry, Queen Mary University of London, London, United Kingdom
| | - Giovanni Finazzi
- Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat a` l'Energie Atomique et aux Energies Alternatives (CEA), Université Grenoble Alpes, Institut National Recherche Agronomique (INRA), Institut de Recherche en Sciences et Technologies pour le Vivant (iRTSV), CEA Grenoble, Grenoble, France
| | - Guy Thomas Hanke
- School of Biochemistry and Chemistry, Queen Mary University of London, London, United Kingdom.,Department of Plant Physiology, Faculty of Biology and Chemistry, University of Osnabrück, Osnabrück, Germany
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16
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Rantala M, Rantala S, Aro EM. Composition, phosphorylation and dynamic organization of photosynthetic protein complexes in plant thylakoid membrane. Photochem Photobiol Sci 2021; 19:604-619. [PMID: 32297616 DOI: 10.1039/d0pp00025f] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The photosystems (PS), catalyzing the photosynthetic reactions of higher plants, are unevenly distributed in the thylakoid membrane: PSII, together with its light harvesting complex (LHC)II, is enriched in the appressed grana stacks, while PSI-LHCI resides in the non-appressed stroma thylakoids, which wind around the grana stacks. The two photosystems interact in a third membrane domain, the grana margins, which connect the grana and stroma thylakoids and allow the loosely bound LHCII to serve as an additional antenna for PSI. The light harvesting is balanced by reversible phosphorylation of LHCII proteins. Nevertheless, light energy also damages PSII and the repair process is regulated by reversible phosphorylation of PSII core proteins. Here, we discuss the detailed composition and organization of PSII-LHCII and PSI-LHCI (super)complexes in the thylakoid membrane of angiosperm chloroplasts and address the role of thylakoid protein phosphorylation in dynamics of the entire protein complex network of the photosynthetic membrane. Finally, we scrutinize the phosphorylation-dependent dynamics of the protein complexes in context of thylakoid ultrastructure and present a model on the reorganization of the entire thylakoid network in response to changes in thylakoid protein phosphorylation.
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Affiliation(s)
- Marjaana Rantala
- Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520, Turku, Finland
| | - Sanna Rantala
- Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520, Turku, Finland
| | - Eva-Mari Aro
- Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20520, Turku, Finland.
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17
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Li M, Mukhopadhyay R, Svoboda V, Oung HMO, Mullendore DL, Kirchhoff H. Measuring the dynamic response of the thylakoid architecture in plant leaves by electron microscopy. PLANT DIRECT 2020; 4:e00280. [PMID: 33195966 PMCID: PMC7644818 DOI: 10.1002/pld3.280] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/15/2020] [Accepted: 09/29/2020] [Indexed: 05/19/2023]
Abstract
UNLABELLED The performance of the photosynthesis machinery in plants, including light harvesting, electron transport, and protein repair, is controlled by structural changes in the thylakoid membrane system inside the chloroplasts. In particular, the structure of the stacked grana area of thylakoid membranes is highly dynamic, changing in response to different environmental cues such as light intensity. For example, the aqueous thylakoid lumen enclosed by thylakoid membranes in grana has been documented to swell in the presence of light. However, light-induced alteration of the stromal gap in the stacked grana (partition gap) and of the unstacked stroma lamellae has not been well characterized. Light-induced changes in the entire thylakoid membrane system, including the lumen in both stacked and unstacked domains as well as the partition gap, are presented here, and the functional implications are discussed. This structural analysis was made possible by development of a robust semi-automated image analysis method combined with optimized plant tissue fixation techniques for transmission electron microscopy generating quantitative structural results for the analysis of thylakoid ultrastructure. SIGNIFICANCE STATEMENT A methodical pipeline ranging from optimized leaf tissue preparation for electron microscopy to quantitative image analysis was established. This methodical development was employed to study details of light-induced changes in the plant thylakoid ultrastructure. It was found that the lumen of the entire thylakoid system (stacked and unstacked domains) undergoes light-induced swelling, whereas adjacent membranes on the stroma side in stacked grana thylakoid approach each other.
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Affiliation(s)
- Meng Li
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
- Present address:
School of OceanographyUniversity of WashingtonSeattleWAUSA
| | - Roma Mukhopadhyay
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
| | - Václav Svoboda
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
| | | | | | - Helmut Kirchhoff
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
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18
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Specific thylakoid protein phosphorylations are prerequisites for overwintering of Norway spruce ( Picea abies) photosynthesis. Proc Natl Acad Sci U S A 2020; 117:17499-17509. [PMID: 32690715 PMCID: PMC7395503 DOI: 10.1073/pnas.2004165117] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Coping of evergreen conifers in boreal forests with freezing temperatures on bright winter days puts the photosynthetic machinery in great risk of oxidative damage. To survive harsh winter conditions, conifers have evolved a unique but poorly characterized photoprotection mechanism, a sustained form of nonphotochemical quenching (sustained NPQ). Here we focused on functional properties and underlying molecular mechanisms related to the development of sustained NPQ in Norway spruce (Picea abies). Data were collected during 4 consecutive years (2016 to 2019) from trees growing in sun and shade habitats. When day temperatures dropped below -4 °C, the specific N-terminally triply phosphorylated LHCB1 isoform (3p-LHCII) and phosphorylated PSBS (p-PSBS) could be detected in the thylakoid membrane. Development of sustained NPQ coincided with the highest level of 3p-LHCII and p-PSBS, occurring after prolonged coincidence of bright winter days and temperatures close to -10 °C. Artificial induction of both the sustained NPQ and recovery from naturally induced sustained NPQ provided information on differential dynamics and light-dependence of 3p-LHCII and p-PSBS accumulation as prerequisites for sustained NPQ. Data obtained collectively suggest three components related to sustained NPQ in spruce: 1) Freezing temperatures induce 3p-LHCII accumulation independently of light, which is suggested to initiate destacking of appressed thylakoid membranes due to increased electrostatic repulsion of adjacent membranes; 2) p-PSBS accumulation is both light- and temperature-dependent and closely linked to the initiation of sustained NPQ, which 3) in concert with PSII photoinhibition, is suggested to trigger sustained NPQ in spruce.
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19
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Negi S, Perrine Z, Friedland N, Kumar A, Tokutsu R, Minagawa J, Berg H, Barry AN, Govindjee G, Sayre R. Light regulation of light-harvesting antenna size substantially enhances photosynthetic efficiency and biomass yield in green algae †. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:584-603. [PMID: 32180283 DOI: 10.1111/tpj.14751] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 02/06/2020] [Accepted: 03/09/2020] [Indexed: 05/25/2023]
Abstract
One of the major factors limiting biomass productivity in algae is the low thermodynamic efficiency of photosynthesis. The greatest thermodynamic inefficiencies in photosynthesis occur during the conversion of light into chemical energy. At full sunlight the light-harvesting antenna captures photons at a rate nearly 10 times faster than the rate-limiting step in photosynthetic electron transport. Excess captured energy is dissipated by non-productive pathways including the production of reactive oxygen species. Substantial improvements in photosynthetic efficiency have been achieved by reducing the optical cross-section of the light-harvesting antenna by selectively reducing chlorophyll b levels and peripheral light-harvesting complex subunits. Smaller light-harvesting antenna, however, may not exhibit optimal photosynthetic performance in low or fluctuating light environments. We describe a translational control system to dynamically adjust light-harvesting antenna sizes for enhanced photosynthetic performance. By expressing a chlorophyllide a oxygenase (CAO) gene having a 5' mRNA extension encoding a Nab1 translational repressor binding site in a CAO knockout line it was possible to continuously alter chlorophyll b levels and correspondingly light-harvesting antenna sizes by light-activated Nab1 repression of CAO expression as a function of growth light intensity. Significantly, algae having light-regulated antenna sizes had substantially higher photosynthetic rates and two-fold greater biomass productivity than the parental wild-type strains as well as near wild-type ability to carry out state transitions and non-photochemical quenching. These results have broad implications for enhanced algae and plant biomass productivity.
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Affiliation(s)
- Sangeeta Negi
- New Mexico Consortium and Los Alamos National Laboratory, Los Alamos, NM, 87544, USA
| | - Zoee Perrine
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
| | | | - Anil Kumar
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
| | - Ryutaro Tokutsu
- Division of Environmental Photobiology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
- CREST (Core Research for Evolutional Science and Technology), Japan Science and Technology Agency (JST), 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
| | - Jun Minagawa
- Division of Environmental Photobiology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
- CREST (Core Research for Evolutional Science and Technology), Japan Science and Technology Agency (JST), 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
| | - Howard Berg
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
| | - Amanda N Barry
- Los Alamos National Laboratory, Los Alamos, NM, 87544, USA
| | - Govindjee Govindjee
- Department of Biochemistry, Department of Plant Biology, Center of Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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20
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Zavafer A, González-Solís A, Palacios-Bahena S, Saucedo-García M, Tapia de Aquino C, Vázquez-Santana S, King-Díaz B, Gavilanes-Ruiz M. Organized Disassembly of Photosynthesis During Programmed Cell Death Mediated By Long Chain Bases. Sci Rep 2020; 10:10360. [PMID: 32587330 PMCID: PMC7316715 DOI: 10.1038/s41598-020-65186-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 04/27/2020] [Indexed: 11/09/2022] Open
Abstract
In plants, pathogen triggered programmed cell death (PCD) is frequently mediated by polar lipid molecules referred as long chain bases (LCBs) or ceramides. PCD interceded by LCBs is a well-organized process where several cell organelles play important roles. In fact, light-dependent reactions in the chloroplast have been proposed as major players during PCD, however, the functional aspects of the chloroplast during PCD are largely unknown. For this reason, we investigated events that lead to disassembly of the chloroplast during PCD mediated by LCBs. To do so, LCB elevation was induced with Pseudomonas syringae pv. tomato (a non-host pathogen) or Fumonisin B1 in Phaseolus vulgaris. Then, we performed biochemical tests to detect PCD triggering events (phytosphingosine rises, MPK activation and H2O2 generation) followed by chloroplast structural and functional tests. Observations of the chloroplast, via optical phenotyping methods combined with microscopy, indicated that the loss of photosynthetic linear electron transport coincides with the organized ultrastructure disassembly. In addition, structural changes occurred in parallel with accumulation of H2O2 inside the chloroplast. These features revealed the collapse of chloroplast integrity and function as a mechanism leading to the irreversible execution of the PCD promoted by LCBs.
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Affiliation(s)
- Alonso Zavafer
- Climate Change Cluster, University of Technology Sydney, Faculty of Science Building 4, Level 6 Corner of Thomas and, Harris St, Ultimo NSW 2007, Sydney, Australia
| | - Ariadna González-Solís
- Dpto. de Bioquímica, Facultad de Química, Conjunto E. Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, 04510, Ciudad de México, México
| | - Silvia Palacios-Bahena
- Dpto. de Bioquímica, Facultad de Química, Conjunto E. Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, 04510, Ciudad de México, México
| | - Mariana Saucedo-García
- Instituto de Ciencias Agropecuarias, Universidad Autónoma del Estado de Hidalgo, Tulancingo, Hidalgo, México
| | - Cinthya Tapia de Aquino
- Dpto. de Bioquímica, Facultad de Química, Conjunto E. Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, 04510, Ciudad de México, México
| | - Sonia Vázquez-Santana
- Dpto. de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, 04510, Ciudad de México, México
| | - Beatriz King-Díaz
- Dpto. de Bioquímica, Facultad de Química, Conjunto E. Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, 04510, Ciudad de México, México
| | - Marina Gavilanes-Ruiz
- Dpto. de Bioquímica, Facultad de Química, Conjunto E. Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, 04510, Ciudad de México, México.
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21
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Wood WHJ, Johnson MP. Modeling the Role of LHCII-LHCII, PSII-LHCII, and PSI-LHCII Interactions in State Transitions. Biophys J 2020; 119:287-299. [PMID: 32621865 DOI: 10.1016/j.bpj.2020.05.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/28/2020] [Accepted: 05/04/2020] [Indexed: 02/08/2023] Open
Abstract
The light-dependent reactions of photosynthesis take place in the plant chloroplast thylakoid membrane, a complex three-dimensional structure divided into the stacked grana and unstacked stromal lamellae domains. Plants regulate the macro-organization of photosynthetic complexes within the thylakoid membrane to adapt to changing environmental conditions and avoid oxidative stress. One such mechanism is the state transition that regulates photosynthetic light harvesting and electron transfer. State transitions are driven by changes in the phosphorylation of light harvesting complex II (LHCII), which cause a decrease in grana diameter and stacking, a decrease in energetic connectivity between photosystem II (PSII) reaction centers, and an increase in the relative LHCII antenna size of photosystem I (PSI) compared to PSII. Phosphorylation is believed to drive these changes by weakening the intramembrane lateral PSII-LHCII and LHCII-LHCII interactions and the intermembrane stacking interactions between these complexes, while simultaneously increasing the affinity of LHCII for PSI. We investigated the relative roles and contributions of these three types of interaction to state transitions using a lattice-based model of the thylakoid membrane based on existing structural data, developing a novel algorithm to simulate protein complex dynamics. Monte Carlo simulations revealed that state transitions are unlikely to lead to a large-scale migration of LHCII from the grana to the stromal lamellae. Instead, the increased light harvesting capacity of PSI is largely due to the more efficient recruitment of LHCII already residing in the stromal lamellae into PSI-LHCII supercomplexes upon its phosphorylation. Likewise, the increased light harvesting capacity of PSII upon dephosphorylation was found to be driven by a more efficient recruitment of LHCII already residing in the grana into functional PSII-LHCII clusters, primarily driven by lateral interactions.
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Affiliation(s)
- William H J Wood
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Matthew P Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom.
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22
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Lattice Models for Protein Organization throughout Thylakoid Membrane Stacks. Biophys J 2020; 118:2680-2693. [PMID: 32413311 DOI: 10.1016/j.bpj.2020.03.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 03/14/2020] [Accepted: 03/24/2020] [Indexed: 11/21/2022] Open
Abstract
Proteins in photosynthetic membranes can organize into patterned arrays that span the membrane's lateral size. Attractions between proteins in different layers of a membrane stack can play a key role in this ordering, as was suggested by microscopy and fluorescence spectroscopy and demonstrated by computer simulations of a coarse-grained model. The architecture of thylakoid membranes, however, also provides opportunities for interlayer interactions that instead disfavor the high protein densities of ordered arrangements. Here, we explore the interplay between these opposing driving forces and, in particular, the phase transitions that emerge in the periodic geometry of stacked thylakoid membrane disks. We propose a lattice model that roughly accounts for proteins' attraction within a layer and across the stromal gap, steric repulsion across the lumenal gap, and regulation of protein density by exchange with the stroma lamellae. Mean-field analysis and computer simulation reveal rich phase behavior for this simple model, featuring a broken-symmetry striped phase that is disrupted at both high and low extremes of chemical potential. The resulting sensitivity of microscopic protein arrangement to the thylakoid's mesoscale vertical structure raises intriguing possibilities for regulation of photosynthetic function.
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23
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Herritt MT, Fritschi FB. Characterization of Photosynthetic Phenotypes and Chloroplast Ultrastructural Changes of Soybean ( Glycine max) in Response to Elevated Air Temperatures. FRONTIERS IN PLANT SCIENCE 2020; 11:153. [PMID: 32210985 PMCID: PMC7069378 DOI: 10.3389/fpls.2020.00153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/31/2020] [Indexed: 05/28/2023]
Abstract
Heat stress negatively affects photosynthesis in crop plants. Chlorophyll fluorescence provides information about the efficiency of the light-dependent reactions of photosynthesis and can be measured non-destructively and rapidly. Four soybean (Glycine max) genotypes were grown in controlled environments at 28/20°C (control), followed by imposition of control, 38/28°C, and 45/28°C day/night temperature regimes for 7 days. Coordinated chlorophyll fluorescence, gas exchange, and chloroplast ultrastructure measurements were conducted over the course of the 7-day temperature treatments and revealed contrasting responses among the different genotypes. Although generally similar, the extent of the impact of elevated temperatures on net photosynthesis differed among genotypes. Despite dramatic effects on photosynthetic light reactions, net photosynthetic rates were not reduced by exposure to 45°C on the 1st day of treatment imposition. Temporal dynamics of light reaction characteristics over the course of the 7-day heat-wave simulation revealed distinct responses among the genotypes. Similarly, chloroplast ultrastructure examination identified contrasting responses of DT97-4290 and PI603166, particularly with respect to starch characteristics. These changes were positively associated with differences in the percent area of chloroplasts that were occupied by starch grains. Elevated temperature increased number and size of starch grains on the 1st day of DT97-4290 which was coordinated with increased minimum chlorophyll fluorescence (F0) and reduced leaf net CO2 assimilation (A). Whereas on the 7th day the elevated temperature treatment showed reduced numbers and sizes of starch grains in chloroplasts and was coordinated with similar levels of F0 and A to the control treatment. Unlike starch dynamics of PI603166 which elevated temperature had little effect on. The genotypic differences in photosynthetic and chloroplast ultrastructure responses to elevated temperatures identified here are of interest for the development of more tolerant soybean cultivars and to facilitate the dissection of molecular mechanisms underpinning heat stress tolerance of soybean photosynthesis.
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Affiliation(s)
- Matthew T. Herritt
- US Arid Land Agricultural Research Center, United States Department of Agriculture, Agricultural Research Service, Maricopa, AZ, United States
| | - Felix B. Fritschi
- Division of Plant Science, University of Missouri, Columbia, MO, United States
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Zsiros O, Ünnep R, Nagy G, Almásy L, Patai R, Székely NK, Kohlbrecher J, Garab G, Dér A, Kovács L. Role of Protein-Water Interface in the Stacking Interactions of Granum Thylakoid Membranes-As Revealed by the Effects of Hofmeister Salts. FRONTIERS IN PLANT SCIENCE 2020; 11:1257. [PMID: 32922427 PMCID: PMC7456932 DOI: 10.3389/fpls.2020.01257] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/30/2020] [Indexed: 05/08/2023]
Abstract
The thylakoid membranes of vascular plants are differentiated into stacked granum and unstacked stroma regions. The formation of grana is triggered by the macrodomain formation of photosystem II and light-harvesting complex II (PSII-LHCII) and thus their lateral segregation from the photosystem I-light-harvesting complex I (PSI-LHCI) super-complexes and the ATP-synthase; which is then stabilized by stacking interactions of the adjacent PSII-LHCII enriched regions of the thylakoid membranes. The self-assembly and dynamics of this highly organized membrane system and the nature of forces acting between the PSII-LHCII macrodomains are not well understood. By using circular dichroism (CD) spectroscopy, small-angle neutron scattering (SANS) and transmission electron microscopy (TEM), we investigated the effects of Hofmeister salts on the organization of pigment-protein complexes and on the ultrastructure of thylakoid membranes. We found that the kosmotropic agent (NH4)2SO4 and the Hofmeister-neutral NaCl, up to 2 M concentrations, hardly affected the macro-organization of the protein complexes and the membrane ultrastructure. In contrast, chaotropic salts, NaClO4, and NaSCN destroyed the mesoscopic structures, the multilamellar organization of the thylakoid membranes and the chiral macrodomains of the protein complexes but without noticeably affecting the short-range, pigment-pigment excitonic interactions. Comparison of the concentration- and time-dependences of SANS, TEM and CD parameters revealed the main steps of the disassembly of grana in the presence of chaotropes. It begins with a rapid diminishment of the long-range periodic order of the grana membranes, apparently due to an increased stacking disorder of the thylakoid membranes, as reflected by SANS experiments. SANS measurements also allowed discrimination between the cationic and anionic effects-in stacking and disorder, respectively. This step is followed by a somewhat slower disorganization of the TEM ultrastructure, due to the gradual loss of stacked membrane pairs. Occurring last is the stepwise decrease and disappearance of the long-range chiral order of the protein complexes, the rate of which was faster in LHCII-deficient membranes. These data are interpreted in terms of a theory, from our laboratory, according to which Hofmeister salts primarily affect the hydrophylic-hydrophobic interactions of proteins, and the stroma-exposed regions of the intrinsic membrane proteins, in particular-pointing to the role of protein-water interface in the stacking interactions of granum thylakoid membranes.
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Affiliation(s)
- Ottó Zsiros
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | - Renáta Ünnep
- Neutron Spectroscopy Department, Centre for Energy Research, Budapest, Hungary
| | - Gergely Nagy
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, Villigen PSI, Switzerland
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Budapest, Hungary
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - László Almásy
- Neutron Spectroscopy Department, Centre for Energy Research, Budapest, Hungary
| | - Roland Patai
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Noémi K. Székely
- Jülich Centre for Neutron Science at MLZ, Forschungszentrum Jülich GmbH, Garching, Germany
| | - Joachim Kohlbrecher
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, Villigen PSI, Switzerland
| | - Győző Garab
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
- Department of Physics, Faculty of Science, University of Ostrava, Ostrava, Czechia
- *Correspondence: Győző Garab, ; András Dér, ; László Kovács,
| | - András Dér
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
- *Correspondence: Győző Garab, ; András Dér, ; László Kovács,
| | - László Kovács
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
- *Correspondence: Győző Garab, ; András Dér, ; László Kovács,
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25
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Bussi Y, Shimoni E, Weiner A, Kapon R, Charuvi D, Nevo R, Efrati E, Reich Z. Fundamental helical geometry consolidates the plant photosynthetic membrane. Proc Natl Acad Sci U S A 2019; 116:22366-22375. [PMID: 31611387 PMCID: PMC6825288 DOI: 10.1073/pnas.1905994116] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Plant photosynthetic (thylakoid) membranes are organized into complex networks that are differentiated into 2 distinct morphological and functional domains called grana and stroma lamellae. How the 2 domains join to form a continuous lamellar system has been the subject of numerous studies since the mid-1950s. Using different electron tomography techniques, we found that the grana and stroma lamellae are connected by an array of pitch-balanced right- and left-handed helical membrane surfaces of different radii and pitch. Consistent with theoretical predictions, this arrangement is shown to minimize the surface and bending energies of the membranes. Related configurations were proposed to be present in the rough endoplasmic reticulum and in dense nuclear matter phases theorized to exist in neutron star crusts, where the right- and left-handed helical elements differ only in their handedness. Pitch-balanced helical elements of alternating handedness may thus constitute a fundamental geometry for the efficient packing of connected layers or sheets.
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Affiliation(s)
- Yuval Bussi
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Allon Weiner
- Centre d'Immunologie et des Maladies Infectieuses, Cimi-Paris, INSERM, Sorbonne Université, 75013 Paris, France
| | - Ruti Kapon
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dana Charuvi
- Institute of Plant Sciences, Agricultural Research Organization - Volcani Center, 7505101 Rishon LeZion, Israel
| | - Reinat Nevo
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Efi Efrati
- Department of Physics of Complex Systems, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Ziv Reich
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel;
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26
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Macroorganisation and flexibility of thylakoid membranes. Biochem J 2019; 476:2981-3018. [DOI: 10.1042/bcj20190080] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 09/19/2019] [Accepted: 10/03/2019] [Indexed: 02/07/2023]
Abstract
Abstract
The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.
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Mezzenga R, Seddon JM, Drummond CJ, Boyd BJ, Schröder-Turk GE, Sagalowicz L. Nature-Inspired Design and Application of Lipidic Lyotropic Liquid Crystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900818. [PMID: 31222858 DOI: 10.1002/adma.201900818] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/16/2019] [Indexed: 05/20/2023]
Abstract
Amphiphilic lipids aggregate in aqueous solution into a variety of structural arrangements. Among the plethora of ordered structures that have been reported, many have also been observed in nature. In addition, due to their unique morphologies, the hydrophilic and hydrophobic domains, very high internal interfacial surface area, and the multitude of possible order-order transitions depending on environmental changes, very promising applications have been developed for these systems in recent years. These include crystallization in inverse bicontinuous cubic phases for membrane protein structure determination, generation of advanced materials, sustained release of bioactive molecules, and control of chemical reactions. The outstanding diverse functionalities of lyotropic liquid crystalline phases found in nature and industry are closely related to the topology, including how their nanoscopic domains are organized. This leads to notable examples of correlation between structure and macroscopic properties, which is itself central to the performance of materials in general. The physical origin of the formation of the known classes of lipidic lyotropic liquid crystalline phases, their structure, and their occurrence in nature are described, and their application in materials science and engineering, biology, medical, and pharmaceutical products, and food science and technology are exemplified.
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Affiliation(s)
- Raffaele Mezzenga
- ETH Zurich Department of Health Sciences and Technology, Schmelzbergstrasse 9, LFO E23, Zurich, 8092, Switzerland
- ETH Zurich Department of Materials, Wolfgang-Pauli-Strasse 10, Zurich, 8093, Switzerland
| | - John M Seddon
- Chemistry Department, Imperial College London, MSRH, Wood Lane, London, W12 0BZ, UK
| | - Calum J Drummond
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria, 3000, Australia
| | - Ben J Boyd
- Drug Delivery, Disposition and Dynamics and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria, 3052, Australia
| | - Gerd E Schröder-Turk
- College of Science, Health, Engineering and Education, Murdoch University, 90 South St, Murdoch, WA, 6150, Australia
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958, Frederiksberg C, Denmark
- Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Lund, 22100, Sweden
| | - Laurent Sagalowicz
- Institute of Materials Science, Nestlé Research Center, CH-1000, Lausanne 26, Switzerland
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28
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Strašková A, Steinbach G, Konert G, Kotabová E, Komenda J, Tichý M, Kaňa R. Pigment-protein complexes are organized into stable microdomains in cyanobacterial thylakoids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:148053. [PMID: 31344362 DOI: 10.1016/j.bbabio.2019.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/28/2019] [Accepted: 07/18/2019] [Indexed: 02/03/2023]
Abstract
Thylakoids are the place of the light-photosynthetic reactions. To gain maximal efficiency, these reactions are conditional to proper pigment-pigment and protein-protein interactions. In higher plants thylakoids, the interactions lead to a lateral asymmetry in localization of protein complexes (i.e. granal/stromal thylakoids) that have been defined as a domain-like structures characteristic by different biochemical composition and function (Albertsson P-Å. 2001,Trends Plant Science 6: 349-354). We explored this complex organization of thylakoid pigment-proteins at single cell level in the cyanobacterium Synechocystis sp. PCC 6803. Our 3D confocal images captured heterogeneous distribution of all main photosynthetic pigment-protein complexes (PPCs), Photosystem I (fluorescently tagged by YFP), Photosystem II and Phycobilisomes. The acquired images depicted cyanobacterial thylakoid membrane as a stable, mosaic-like structure formed by microdomains (MDs). These microcompartments are of sub-micrometer in sizes (~0.5-1.5 μm), typical by particular PPCs ratios and importantly without full segregation of observed complexes. The most prevailing MD is represented by MD with high Photosystem I content which allows also partial separation of Photosystems like in higher plants thylakoids. We assume that MDs stability (in minutes) provides optimal conditions for efficient excitation/electron transfer. The cyanobacterial MDs thus define thylakoid membrane organization as a system controlled by co-localization of three main PPCs leading to formation of thylakoid membrane mosaic. This organization might represent evolutional and functional precursor for the granal/stromal spatial heterogeneity in photosystems that is typical for higher plant thylakoids.
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Affiliation(s)
- A Strašková
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - G Steinbach
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - G Konert
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - E Kotabová
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - J Komenda
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - M Tichý
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - R Kaňa
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic.
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29
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Kowalewska Ł, Bykowski M, Mostowska A. Spatial organization of thylakoid network in higher plants. BOTANY LETTERS 2019. [PMID: 0 DOI: 10.1080/23818107.2019.1619195] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- Łucja Kowalewska
- Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Michał Bykowski
- Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Agnieszka Mostowska
- Department of Plant Anatomy and Cytology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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30
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Doltchinkova V, Andreeva T, Georgieva K, Mihailova G, Balashev K. Desiccation-induced alterations in surface topography of thylakoids from resurrection plant Haberlea rhodopensis studied by atomic force microscopy, electrokinetic and optical measurements. PHYSIOLOGIA PLANTARUM 2019; 166:585-595. [PMID: 30043985 DOI: 10.1111/ppl.12807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
With their ability to survive complete desiccation, resurrection plants are a suitable model system for studying the mechanisms of drought tolerance. In the present study, we investigated desiccation-induced alterations in surface topography of thylakoids isolated from well-hydrated, moderately dehydrated, severely desiccated and rehydrated Haberlea rhodopensis plants by means of atomic force microscopy (AFM), electrokinetic and optical measurements. According to our knowledge, so far, there were no reports on the characterization of surface topography and polydispersity of thylakoid membranes from resurrection plants using AFM and dynamic light scattering. To study the physicochemical properties of thylakoids from well-hydrated H. rhodopensis plants, we used spinach thylakoids for comparison as a classical model from higher plants. The thylakoids from well-hydrated H. rhodopensis had a grainy surface, significantly different from the well-structured spinach thylakoids with distinct grana and lamella, they had twice smaller cross-sectional area and were 1.5 times less voluminous than that of spinach. Significant differences in their physicochemical properties were observed. The dehydration and subsequent rehydration of plants affected the size, shape, morphology, roughness and therefore the structure of the studied thylakoids. Drought resulted in significant enhancement of negative charges on the outer surface of thylakoid membranes which correlated with the increased roughness of thylakoid surface. This enhancement in surface charge density could be due to the partial unstacking of thylakoids exposing more negatively charged groups from protein complexes on the membrane surface that prevent from possible aggregation upon drought stress.
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Affiliation(s)
- Virjinia Doltchinkova
- Department of Biophysics and Radiobiology, Faculty of Biology, Sofia University "St. Kliment Ohridski", 1164, Sofia, Bulgaria
| | - Tonya Andreeva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Katya Georgieva
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Gergana Mihailova
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Konstantin Balashev
- Laboratory of Biophysical Chemistry, Department of Physical Chemistry, Faculty of Chemistry and Pharmacia, Sofia University "St. Kliment Ohridski", 1164, Sofia, Bulgaria
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31
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López-Pozo M, Gasulla F, García-Plazaola JI, Fernández-Marín B. Unraveling metabolic mechanisms behind chloroplast desiccation tolerance: Chlorophyllous fern spore as a new promising unicellular model. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 281:251-260. [PMID: 30824058 DOI: 10.1016/j.plantsci.2018.11.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/25/2018] [Accepted: 11/20/2018] [Indexed: 05/15/2023]
Abstract
Fern spores are unicellular structures produced by the sporophyte generation that give rise to the haploid gametophyte. When released from the sporangium, spores are desiccation tolerant (DT) in the royal fern (Osmunda regalis) and contain fully developed chloroplasts. As a consequence, this type of spores is called chlorophyllous spores (CS). Upon transfer to germination conditions, CS initiate a process of imbibition that suppresses DT in 72 h, before the germination starts. In parallel to such change in DT, thylakoids undergo a profound remodelling in composition and function. Firstly, sustained quenching of chlorophyll fluorescence is relaxed, giving rise to photochemically active CS, while lipid composition shifts from that of a resting structure to a metabolically active cell. Basically trigalactolipids decreased in favour of monogalactolipids, with a parallel desaturation of fatty acids. Storage lipids such as triacylglycerol were quickly depleted. These results highlight the importance of the structure of thylakoids lipid as a key to protect membrane integrity during desiccation, together with the saturation of fatty acids and the constitutive chlorophyll quenching to prevent oxidative damage. The CS used here, in which the same cell shifts from DT to sensitive strategy in 72 h, reveal their potential as unicellular models for future studies on DT.
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Affiliation(s)
- M López-Pozo
- Dpto. Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, 48940, Bilbao, Spain.
| | - F Gasulla
- Dpto. de Ciencias de la Vida, Universidad de Alcalá, 28805, Alcalá de Henares, Madrid, Spain
| | - J I García-Plazaola
- Dpto. Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, 48940, Bilbao, Spain
| | - B Fernández-Marín
- Dpto. Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, 48940, Bilbao, Spain
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32
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Koochak H, Puthiyaveetil S, Mullendore DL, Li M, Kirchhoff H. The structural and functional domains of plant thylakoid membranes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:412-429. [PMID: 30312499 DOI: 10.1111/tpj.14127] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/24/2018] [Accepted: 10/01/2018] [Indexed: 05/07/2023]
Abstract
In plants, the stacking of part of the photosynthetic thylakoid membrane generates two main subcompartments: the stacked grana core and unstacked stroma lamellae. However, a third distinct domain, the grana margin, has been postulated but its structural and functional identity remains elusive. Here, an optimized thylakoid fragmentation procedure combined with detailed ultrastructural, biochemical, and functional analyses reveals the distinct composition of grana margins. It is enriched with lipids, cytochrome b6 f complex, and ATPase while depleted in photosystems and light-harvesting complexes. A quantitative method is introduced that is based on Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) and dot immunoblotting for quantifying various photosystem II (PSII) assembly forms in different thylakoid subcompartments. The results indicate that the grana margin functions as a degradation and disassembly zone for photodamaged PSII. In contrast, the stacked grana core region contains fully assembled and functional PSII holocomplexes. The stroma lamellae, finally, contain monomeric PSII as well as a significant fraction of dimeric holocomplexes that identify this membrane area as the PSII repair zone. This structural organization and the heterogeneous PSII distribution support the idea that the stacking of thylakoid membranes leads to a division of labor that establishes distinct membrane areas with specific functions.
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Affiliation(s)
- Haniyeh Koochak
- Institute of Biological Chemistry, Washington State University, PO Box 646340, Pullman, WA, 99164-6340, USA
| | - Sujith Puthiyaveetil
- Institute of Biological Chemistry, Washington State University, PO Box 646340, Pullman, WA, 99164-6340, USA
| | - Daniel L Mullendore
- Franceschi Microscopy and Imaging Center, Washington State University, Pullman, WA, 99164, USA
| | - Meng Li
- Institute of Biological Chemistry, Washington State University, PO Box 646340, Pullman, WA, 99164-6340, USA
| | - Helmut Kirchhoff
- Institute of Biological Chemistry, Washington State University, PO Box 646340, Pullman, WA, 99164-6340, USA
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33
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Petrova N, Todinova S, Paunov M, Kovács L, Taneva S, Krumova S. Thylakoid membrane unstacking increases LHCII thermal stability and lipid phase fluidity. J Bioenerg Biomembr 2018; 50:425-435. [PMID: 30607760 DOI: 10.1007/s10863-018-9783-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 12/20/2018] [Indexed: 11/26/2022]
Abstract
Thylakoids are highly protein-enriched membranes that harbor a number of multicomponent photosynthetic complexes. Similarly to other biological membranes the protein constituents are heterogeneously distributed laterally in the plane of the membrane, however the specific segregation into stacked (grana patches) and unstacked (stroma lamellae) membrane layers is a unique feature of the thylakoid. Both the lateral and the vertical arrangements of the integral membrane proteins within the three-dimensional thylakoid ultrastructure are thought to have important physiological function. In this work we explore the role of membrane stacking for the thermal stability of the photosynthetic complexes in thylakoid membranes. By means of circular dichroism and differential scanning calorimetry we demonstrate that the thermal stability of the monomeric and trimeric forms of the major light harvesting complex of photosystem II (LHCII) increases upon unstacking. This effect was suggested to be due to the detachment of LHCII from photosystem II and consequent attachment to photosystem I subunits and/or the fluidization of the lipid matrix upon unstacking. The changes in the physical properties of the protein and lipid membrane components upon unstacking result in strongly reduced photosystem II excitation energy utilization.
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Affiliation(s)
- Nia Petrova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Svetla Todinova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Momchil Paunov
- Department of Biophysics and Radiobiology, Faculty of Biology, Sofia University "St. Kliment Ohridski", Sofia, Bulgaria
| | - Lászlo Kovács
- Biological Research Centre, Institute of Plant Biology, Szeged, Hungary
| | - Stefka Taneva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Sashka Krumova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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34
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Jäger S, Büchel C. Cation-dependent changes in the thylakoid membrane appression of the diatom Thalassiosira pseudonana. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1860:41-51. [PMID: 30447184 DOI: 10.1016/j.bbabio.2018.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 09/21/2018] [Accepted: 11/04/2018] [Indexed: 11/16/2022]
Abstract
Diatoms show a special organisation of their plastid membranes, such that their thylakoids span the entire plastid in bands of three. While in higher plants the interaction of the light harvesting complex II and photosystem II with divalent cations (especially Mg2+) was found to take part in the interplay of electrostatic attraction and repulsion in grana membrane appression, for diatoms the key players in maintaining proper membrane distances were not identified so far. In this work, we investigated the changes in the thylakoid architecture of Thalassiosira pseudonana in reaction to different salts by using circular dichroism and fluorescence spectroscopy in combination with other techniques. We show that divalent cations have an important influence on optimal pigment organisation and thus also on maintaining membrane appression. Thereby, monovalent cations are far less effective. The concentration needed is in a physiological range and fits well with the values obtained for higher plant grana stacking, despite the fact that strict protein segregation as seen in higher plant grana is missing.
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Affiliation(s)
- Stefanie Jäger
- Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt, Germany
| | - Claudia Büchel
- Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt, Germany.
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35
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Plastid terminal oxidase requires translocation to the grana stacks to act as a sink for electron transport. Proc Natl Acad Sci U S A 2018; 115:9634-9639. [PMID: 30181278 DOI: 10.1073/pnas.1719070115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The plastid terminal oxidase (PTOX) has been shown to be an important sink for photosynthetic electron transport in stress-tolerant plants. However, overexpression studies in stress-sensitive species have previously failed to induce significant activity of this protein. Here we show that overexpression of PTOX from the salt-tolerant brassica species Eutrema salsugineum does not, alone, result in activity, but that overexpressing plants show faster induction and a greater final level of PTOX activity once exposed to salt stress. This implies that an additional activation step is required before activity is induced. We show that that activation involves the translocation of the protein from the unstacked stromal lamellae to the thylakoid grana and a protection of the protein from trypsin digestion. This represents an important activation step and opens up possibilities in the search for stress-tolerant crops.
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Seiwert D, Witt H, Ritz S, Janshoff A, Paulsen H. The Nonbilayer Lipid MGDG and the Major Light-Harvesting Complex (LHCII) Promote Membrane Stacking in Supported Lipid Bilayers. Biochemistry 2018; 57:2278-2288. [PMID: 29577715 DOI: 10.1021/acs.biochem.8b00118] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The thylakoid membrane of algae and land plants is characterized by its intricate architecture, comprising tightly appressed membrane stacks termed grana. The contributions of individual components to grana stack formation are not yet fully elucidated. As an in vitro model, we use supported lipid bilayers made of thylakoid lipid mixtures to study the effect of major light-harvesting complex (LHCII), different lipids, and ions on membrane stacking, seen as elevated structures forming on top of the planar membrane surface in the presence of LHCII protein. These structures were examined by confocal laser scanning microscopy, atomic force microscopy, and fluorescence recovery after photobleaching, revealing multilamellar LHCII-membrane stacks composed of connected lipid bilayers. Both native-like and non-native interactions between the LHCII complexes may contribute to membrane appression in the supported bilayers. However, applying in vivo-like salt conditions to uncharged glycolipid membranes drastically increased the level of stack formation due to enforced LHCII-LHCII interactions, which is in line with recent crystallographic and cryo-electron microscopic data [Wan, T., et al. (2014) Mol. Plant 7, 916-919; Albanese, P., et al. (2017) Sci. Rep. 7, 10067-10083]. Furthermore, we observed the nonbilayer lipid MGDG to strongly promote membrane stacking, pointing to the long-term proposed function of MGDG in stabilizing the inner membrane leaflet of highly curved margins in the periphery of each grana disc because of its negative intrinsic curvature [Murphy, D. J. (1982) FEBS Lett. 150, 19-26].
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Affiliation(s)
- Dennis Seiwert
- Institute of Molecular Physiology , Johannes Gutenberg University Mainz , Johannes-von-Müller-Weg 6 , 55128 Mainz , Germany
| | - Hannes Witt
- Institute of Physical Chemistry , University of Goettingen , Tammannstrasse 6 , 37077 Goettingen , Germany
| | - Sandra Ritz
- Microscopy Core Facility , Institute of Molecular Biology , Ackermannweg 4 , 55128 Mainz , Germany
| | - Andreas Janshoff
- Institute of Physical Chemistry , University of Goettingen , Tammannstrasse 6 , 37077 Goettingen , Germany
| | - Harald Paulsen
- Institute of Molecular Physiology , Johannes Gutenberg University Mainz , Johannes-von-Müller-Weg 6 , 55128 Mainz , Germany
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37
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Schwarz EM, Tietz S, Froehlich JE. Photosystem I-LHCII megacomplexes respond to high light and aging in plants. PHOTOSYNTHESIS RESEARCH 2018; 136:107-124. [PMID: 28975583 PMCID: PMC5851685 DOI: 10.1007/s11120-017-0447-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 09/21/2017] [Indexed: 05/18/2023]
Abstract
Photosystem II is known to be a highly dynamic multi-protein complex that participates in a variety of regulatory and repair processes. In contrast, photosystem I (PSI) has, until quite recently, been thought of as relatively static. We report the discovery of plant PSI-LHCII megacomplexes containing multiple LHCII trimers per PSI reaction center. These PSI-LHCII megacomplexes respond rapidly to changes in light intensity, as visualized by native gel electrophoresis. PSI-LHCII megacomplex formation was found to require thylakoid stacking, and to depend upon growth light intensity and leaf age. These factors were, in turn, correlated with changes in PSI/PSII ratios and, intriguingly, PSI-LHCII megacomplex dynamics appeared to depend upon PSII core phosphorylation. These findings suggest new functions for PSI and a new level of regulation involving specialized subpopulations of photosystem I which have profound implications for current models of thylakoid dynamics.
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Affiliation(s)
- Eliezer M Schwarz
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
| | - Stephanie Tietz
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - John E Froehlich
- Department of Energy 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
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Spetea C, Herdean A, Allorent G, Carraretto L, Finazzi G, Szabo I. An update on the regulation of photosynthesis by thylakoid ion channels and transporters in Arabidopsis. PHYSIOLOGIA PLANTARUM 2017; 161:16-27. [PMID: 28332210 DOI: 10.1111/ppl.12568] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/08/2017] [Accepted: 02/20/2017] [Indexed: 05/07/2023]
Abstract
In natural, variable environments, plants rapidly adjust photosynthesis for optimal balance between light absorption and utilization. There is increasing evidence suggesting that ion fluxes across the chloroplast thylakoid membrane play an important role in this regulation by affecting the proton motive force and consequently photosynthesis and thylakoid membrane ultrastructure. This article presents an update on the thylakoid ion channels and transporters characterized in Arabidopsis thaliana as being involved in these processes, as well as an outlook at the evolutionary conservation of their functions in other photosynthetic organisms. This is a contribution to shed light on the thylakoid network of ion fluxes and how they help plants to adjust photosynthesis in variable light environments.
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Affiliation(s)
- Cornelia Spetea
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, 40530, Sweden
| | - Andrei Herdean
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, 40530, Sweden
| | - Guillaume Allorent
- Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), Université Grenoble Alpes (UGA), Grenoble, 38100, France
| | - Luca Carraretto
- Department of Biology, University of Padova, Padova, Italy
- CNR Institute of Neuroscience, Padova, Italy
| | - Giovanni Finazzi
- Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), Université Grenoble Alpes (UGA), Grenoble, 38100, France
| | - Ildikò Szabo
- Department of Biology, University of Padova, Padova, Italy
- CNR Institute of Neuroscience, Padova, Italy
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Effects of catalase on chloroplast arrangement in Opuntia streptacantha chlorenchyma cells under salt stress. Sci Rep 2017; 7:8656. [PMID: 28819160 PMCID: PMC5561099 DOI: 10.1038/s41598-017-08744-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/13/2017] [Indexed: 01/23/2023] Open
Abstract
In arid and semiarid regions, low precipitation rates lead to soil salinity problems, which may limit plant establishment, growth, and survival. Herein, we investigated the NaCl stress effect on chlorophyll fluorescence, photosynthetic-pigments, movement and chloroplasts ultrastructure in chlorenchyma cells of Opuntia streptacantha cladodes. Cladodes segments were exposed to salt stress at 0, 100, 200, and 300 mM NaCl for 8, 16, and 24 h. The results showed that salt stress reduced chlorophyll content, F v /F m , ΦPSII, and qP values. Under the highest salt stress treatments, the chloroplasts were densely clumped toward the cell center and thylakoid membranes were notably affected. We analyzed the effect of exogenous catalase in salt-stressed cladode segments during 8, 16, and 24 h. The catalase application to salt-stressed cladodes counteracted the NaCl adverse effects, increasing the chlorophyll fluorescence parameters, photosynthetic-pigments, and avoided chloroplast clustering. Our results indicate that salt stress triggered the chloroplast clumping and affected the photosynthesis in O. streptacantha chlorenchyma cells. The exogenous catalase reverted the H2O2 accumulation and clustering of chloroplast, which led to an improvement of the photosynthetic efficiency. These data suggest that H2O2 detoxification by catalase is important to protect the chloroplast, thus conserving the photosynthetic activity in O. streptacantha under stress.
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40
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Kirchhoff H, Li M, Puthiyaveetil S. Sublocalization of Cytochrome b 6f Complexes in Photosynthetic Membranes. TRENDS IN PLANT SCIENCE 2017; 22:574-582. [PMID: 28483636 DOI: 10.1016/j.tplants.2017.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 05/17/2023]
Abstract
It is well established that the majority of energy-converting photosynthetic protein complexes in plant thylakoid membrane are nonhomogenously distributed between stacked and unstacked membrane regions. Yet, the sublocalization of the central cytochrome b6f complex remains controversial. We present a structural model that explains the variation in cytochrome b6f sublocalization data. Small changes in the distance between adjacent membranes in stacked grana regions either allow or restrict access of cytochrome b6f complexes to grana. If the width of the gap falls below a certain threshold, then the steric hindrance prevents cytochrome b6f access to grana. Evidence is presented that the width of stromal gap is variable, demonstrating that the postulated mechanism can regulate the lateral distribution of the cytochrome b6f complexes.
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Affiliation(s)
- Helmut Kirchhoff
- Insitute of Biological Chemistry, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA.
| | - Meng Li
- Insitute of Biological Chemistry, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA
| | - Sujith Puthiyaveetil
- Insitute of Biological Chemistry, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA; Current address: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, IN 47907, USA
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Caspari OD, Meyer MT, Tolleter D, Wittkopp TM, Cunniffe NJ, Lawson T, Grossman AR, Griffiths H. Pyrenoid loss in Chlamydomonas reinhardtii causes limitations in CO2 supply, but not thylakoid operating efficiency. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3903-3913. [PMID: 28911055 PMCID: PMC5853600 DOI: 10.1093/jxb/erx197] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The pyrenoid of the unicellular green alga Chlamydomonas reinhardtii is a microcompartment situated in the centre of the cup-shaped chloroplast, containing up to 90% of cellular Rubisco. Traversed by a network of dense, knotted thylakoid tubules, the pyrenoid has been proposed to influence thylakoid biogenesis and ultrastructure. Mutants that are unable to assemble a pyrenoid matrix, due to expressing a vascular plant version of the Rubisco small subunit, exhibit severe growth and photosynthetic defects and have an ineffective carbon-concentrating mechanism (CCM). The present study set out to determine the cause of photosynthetic limitation in these pyrenoid-less lines. We tested whether electron transport and light use were compromised as a direct structural consequence of pyrenoid loss or as a metabolic effect downstream of lower CCM activity and resulting CO2 limitation. Thylakoid organization was unchanged in the mutants, including the retention of intrapyrenoid-type thylakoid tubules, and photosynthetic limitations associated with the absence of the pyrenoid were rescued by exposing cells to elevated CO2 levels. These results demonstrate that Rubisco aggregation in the pyrenoid functions as an essential element for CO2 delivery as part of the CCM, and does not play other roles in maintenance of photosynthetic membrane energetics.
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Affiliation(s)
- Oliver D Caspari
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK
- Correspondence:
| | - Moritz T Meyer
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK
| | - Dimitri Tolleter
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
| | - Tyler M Wittkopp
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Nik J Cunniffe
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK
| | - Tracy Lawson
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK
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Kanduč M, Schlaich A, de Vries AH, Jouhet J, Maréchal E, Demé B, Netz RR, Schneck E. Tight cohesion between glycolipid membranes results from balanced water-headgroup interactions. Nat Commun 2017; 8:14899. [PMID: 28367975 PMCID: PMC5382269 DOI: 10.1038/ncomms14899] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 02/07/2017] [Indexed: 01/20/2023] Open
Abstract
Membrane systems that naturally occur as densely packed membrane stacks contain high amounts of glycolipids whose saccharide headgroups display multiple small electric dipoles in the form of hydroxyl groups. Experimentally, the hydration repulsion between glycolipid membranes is of much shorter range than that between zwitterionic phospholipids whose headgroups are dominated by a single large dipole. Using solvent-explicit molecular dynamics simulations, here we reproduce the experimentally observed, different pressure-versus-distance curves of phospholipid and glycolipid membrane stacks and show that the water uptake into the latter is solely driven by the hydrogen bond balance involved in non-ideal water/sugar mixing. Water structuring effects and lipid configurational perturbations, responsible for the longer-range repulsion between phospholipid membranes, are inoperative for the glycolipids. Our results explain the tight cohesion between glycolipid membranes at their swelling limit, which we here determine by neutron diffraction, and their unique interaction characteristics, which are essential for the biogenesis of photosynthetic membranes. Glycolipids are commonly found in densely stacked biological membranes, which show unusually strong self-cohesion compared to phospholipid membranes. Here, the authors attribute this phenomenon to the lack of long-range repulsion between glycolipid membranes, a consequence of the headgroup architecture.
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Affiliation(s)
- Matej Kanduč
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.,Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Alexander Schlaich
- Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Alex H de Vries
- Groningen Biomolecular Sciences and Biotechnology (GBB) Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRA, Université Grenoble Alpes, CEA Grenoble, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Eric Maréchal
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRA, Université Grenoble Alpes, CEA Grenoble, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Bruno Demé
- Institut Laue-Langevin, 71 avenue des Martyrs, F-38042 Grenoble Cedex 9, France
| | - Roland R Netz
- Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D-14476 Potsdam, Germany
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Puthiyaveetil S, van Oort B, Kirchhoff H. Surface charge dynamics in photosynthetic membranes and the structural consequences. NATURE PLANTS 2017; 3:17020. [PMID: 28263304 DOI: 10.1038/nplants.2017.20] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 02/03/2017] [Indexed: 05/22/2023]
Abstract
The strict stacking of plant photosynthetic membranes into granal structures plays a vital role in energy conversion. The molecular forces that lead to grana stacking, however, are poorly understood. Here we evaluate the interplay between repulsive electrostatic (Fel) and attractive van der Waals (FvdWaals) forces in grana stacking. In contrast to previous reports, we find that the physicochemical balance between attractive and repulsive forces fully explains grana stacking. Extending the force balance analysis to lateral interactions within the oxygen-evolving photosystem II (PSII)-light harvesting complex II (LHCII) supercomplex reveals that supercomplex stability is very sensitive to Fel changes. Fel is highly dynamic, increasing up to 1.7-fold on addition of negative charges by phosphorylation of grana-hosted proteins. We show that this leads to specific destabilization of the supercomplex, and that changes in Fel have contrasting effects on vertical stacking and lateral intramembrane organization. This enables discrete biological control of these central structural features.
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Affiliation(s)
- Sujith Puthiyaveetil
- Institute of Biological Chemistry, Washington State University, PO Box 646340, Pullman, Washington 99164-6340, USA
| | - Bart van Oort
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Helmut Kirchhoff
- Institute of Biological Chemistry, Washington State University, PO Box 646340, Pullman, Washington 99164-6340, USA
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44
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Castorinis A. The rotational model: a new hypothesis for thylakoid stacking. INTERNATIONAL JOURNAL OF PLANT BIOLOGY 2016. [DOI: 10.4081/pb.2016.6237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The most enigmatic feature of mature thylakoids of Angiosperms is the presence of piles of membranous discs forming the cylindrical structures known as grana. Although some models aim to elucidate their formation, until now the mechanism governing the architecture of thylakoid stacks remains obscure. In this work a new model is presented aiming to explain the way thylakoids stack. In comparison with previous models, this model proposes a dynamic mechanism for the rapid selfassembly of thylakoid stacks and their subsequent disassembly under the influence of a variety of physicochemical factors and is consistent with the evolutionary origin of these membranes and their ontogenetic continuity. The model proposes that, under the influence of attractive electrostatic forces, the membranes come closer in a parallel alignment and the photosystem II/light harvesting complexes migrate laterally forming circular aggregates. Finally the thylakoids rotate around the vertical axis of the superimposed aggregates, under the action of a torque.
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45
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Bastien O, Botella C, Chevalier F, Block MA, Jouhet J, Breton C, Girard-Egrot A, Maréchal E. New Insights on Thylakoid Biogenesis in Plant Cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 323:1-30. [DOI: 10.1016/bs.ircmb.2015.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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46
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Dutta S, Cruz JA, Jiao Y, Chen J, Kramer DM, Osteryoung KW. Non-invasive, whole-plant imaging of chloroplast movement and chlorophyll fluorescence reveals photosynthetic phenotypes independent of chloroplast photorelocation defects in chloroplast division mutants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 84:428-42. [PMID: 26332826 DOI: 10.1111/tpj.13009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/20/2015] [Indexed: 05/23/2023]
Abstract
Leaf chloroplast movement is thought to optimize light capture and to minimize photodamage. To better understand the impact of chloroplast movement on photosynthesis, we developed a technique based on the imaging of reflectance from leaf surfaces that enables continuous, high-sensitivity, non-invasive measurements of chloroplast movement in multiple intact plants under white actinic light. We validated the method by measuring photorelocation responses in Arabidopsis chloroplast division mutants with drastically enlarged chloroplasts, and in phototropin mutants with impaired photorelocation but normal chloroplast morphology, under different light regimes. Additionally, we expanded our platform to permit simultaneous image-based measurements of chlorophyll fluorescence and chloroplast movement. We show that chloroplast division mutants with enlarged, less-mobile chloroplasts exhibit greater photosystem II photodamage than is observed in the wild type, particularly under fluctuating high levels of light. Comparison between division mutants and the severe photorelocation mutant phot1-5 phot2-1 showed that these effects are not entirely attributable to diminished photorelocation responses, as previously hypothesized, implying that altered chloroplast morphology affects other photosynthetic processes. Our dual-imaging platform also allowed us to develop a straightforward approach to correct non-photochemical quenching (NPQ) calculations for interference from chloroplast movement. This correction method should be generally useful when fluorescence and reflectance are measured in the same experiments. The corrected data indicate that the energy-dependent (qE) and photoinhibitory (qI) components of NPQ contribute differentially to the NPQ phenotypes of the chloroplast division and photorelocation mutants. This imaging technology thus provides a platform for analyzing the contributions of chloroplast movement, chloroplast morphology and other phenotypic attributes to the overall photosynthetic performance of higher plants.
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Affiliation(s)
- Siddhartha Dutta
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824-1312, USA
| | - Jeffrey A Cruz
- MSU-DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824-1312, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824-1312, USA
| | - Yuhua Jiao
- MSU-DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824-1312, USA
| | - Jin Chen
- MSU-DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824-1312, USA
- Department of Computer Sciences and Engineering, Michigan State University, East Lansing, MI, 48824-1312, USA
| | - David M Kramer
- MSU-DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824-1312, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824-1312, USA
| | - Katherine W Osteryoung
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824-1312, USA
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47
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Voitsekhovskaja OV, Tyutereva EV. Chlorophyll b in angiosperms: Functions in photosynthesis, signaling and ontogenetic regulation. JOURNAL OF PLANT PHYSIOLOGY 2015; 189:51-64. [PMID: 26513460 DOI: 10.1016/j.jplph.2015.09.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 05/22/2023]
Abstract
Chlorophyll b (Chlb) is an antenna chlorophyll. The binding of Chlb by antenna proteins is crucial for the correct assembly of the antenna complexes in thylakoid membranes. Since the levels of the proteins of major and minor antenna are affected to different extents by Chlb binding, the availability of Chlb influences the composition and the size of antenna complexes which in turn determine the supramolecular organization of the thylakoid membranes in grana. Therefore, Chlb synthesis levels have a major impact on lateral mobility and diffusion of membrane molecules, and thus affect not only light harvesting and thermal energy dissipation processes, but also linear electron transport and repair processes in grana. Furthermore, in angiosperms Chlb synthesis affects plant functions beyond chloroplasts. First, the stability of pigment-protein complexes in the antennae, which depends on Chlb, is an important factor in the regulation of plant ontogenesis, and Chlb levels were recently shown to influence plant ontogenetic signaling. Second, the amounts of minor antenna proteins in chloroplasts, which depend on the availability of Chlb, were recently shown to affect ABA levels and signaling in plants. These mechanisms can be examined in mutants where Chlb synthesis is reduced or abolished. The dramatic effects caused by the lack of Chlb on plant productivity are interpreted in this review in light of the pleiotropic effects on photosynthesis and signaling, and the potential to manipulate Chlb biosynthesis for the improvement of crop production is discussed.
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Affiliation(s)
- O V Voitsekhovskaja
- Komarov Botanical Institute, Russian Academy of Sciences, Plant Ecological Physiology, ul. Professora Popova, 2, 197376 St. Petersburg, Russia.
| | - E V Tyutereva
- Komarov Botanical Institute, Russian Academy of Sciences, Plant Ecological Physiology, ul. Professora Popova, 2, 197376 St. Petersburg, Russia
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48
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Pale-green phenotype of atl31atl6 double mutant leaves is caused by disruption of 5-aminolevulinic acid biosynthesis in Arabidopsis thaliana. PLoS One 2015; 10:e0117662. [PMID: 25706562 PMCID: PMC4338271 DOI: 10.1371/journal.pone.0117662] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/29/2014] [Indexed: 11/19/2022] Open
Abstract
Arabidopsis ubiquitin ligases ATL31 and homologue ATL6 control the carbon/nitrogen nutrient and pathogen responses. A mutant with the loss-of-function of both atl31 and atl6 developed light intensity-dependent pale-green true leaves, whereas the single knockout mutants did not. Plastid ultrastructure and Blue Native-PAGE analyses revealed that pale-green leaves contain abnormal plastid structure with highly reduced levels of thylakoid proteins. In contrast, the pale-green leaves of the atl31/atl6 mutant showed normal Fv/Fm. In the pale-green leaves of the atl31/atl6, the expression of HEMA1, which encodes the key enzyme for 5-aminolevulinic acid synthesis, the rate-limiting step in chlorophyll biosynthesis, was markedly down-regulated. The expression of key transcription factor GLK1, which directly promotes HEMA1 transcription, was also significantly decreased in atl31/atl6 mutant. Finally, application of 5-aminolevulinic acid to the atl31/atl6 mutants resulted in recovery to a green phenotype. Taken together, these findings indicate that the 5-aminolevulinic acid biosynthesis step was inhibited through the down-regulation of chlorophyll biosynthesis-related genes in the pale-green leaves of atl31/atl6 mutant.
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Caffarri S, Tibiletti T, Jennings RC, Santabarbara S. A comparison between plant photosystem I and photosystem II architecture and functioning. Curr Protein Pept Sci 2015; 15:296-331. [PMID: 24678674 PMCID: PMC4030627 DOI: 10.2174/1389203715666140327102218] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 11/22/2013] [Accepted: 03/16/2014] [Indexed: 01/31/2023]
Abstract
Oxygenic photosynthesis is indispensable both for the development and maintenance of life on earth by converting
light energy into chemical energy and by producing molecular oxygen and consuming carbon dioxide. This latter
process has been responsible for reducing the CO2 from its very high levels in the primitive atmosphere to the present low
levels and thus reducing global temperatures to levels conducive to the development of life. Photosystem I and photosystem
II are the two multi-protein complexes that contain the pigments necessary to harvest photons and use light energy to
catalyse the primary photosynthetic endergonic reactions producing high energy compounds. Both photosystems are
highly organised membrane supercomplexes composed of a core complex, containing the reaction centre where electron
transport is initiated, and of a peripheral antenna system, which is important for light harvesting and photosynthetic activity
regulation. If on the one hand both the chemical reactions catalysed by the two photosystems and their detailed structure
are different, on the other hand they share many similarities. In this review we discuss and compare various aspects of
the organisation, functioning and regulation of plant photosystems by comparing them for similarities and differences as
obtained by structural, biochemical and spectroscopic investigations.
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Affiliation(s)
| | | | | | - Stefano Santabarbara
- Laboratoire de Génétique et de Biophysique des Plantes (LGBP), Aix-Marseille Université, Faculté des Sciences de Luminy, 163 Avenue de Luminy, 13009, Marseille, France.
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Engel BD, Schaffer M, Kuhn Cuellar L, Villa E, Plitzko JM, Baumeister W. Native architecture of the Chlamydomonas chloroplast revealed by in situ cryo-electron tomography. eLife 2015; 4. [PMID: 25584625 PMCID: PMC4292175 DOI: 10.7554/elife.04889] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/08/2014] [Indexed: 12/19/2022] Open
Abstract
Chloroplast function is orchestrated by the organelle's intricate architecture. By combining cryo-focused ion beam milling of vitreous Chlamydomonas cells with cryo-electron tomography, we acquired three-dimensional structures of the chloroplast in its native state within the cell. Chloroplast envelope inner membrane invaginations were frequently found in close association with thylakoid tips, and the tips of multiple thylakoid stacks converged at dynamic sites on the chloroplast envelope, implicating lipid transport in thylakoid biogenesis. Subtomogram averaging and nearest neighbor analysis revealed that RuBisCO complexes were hexagonally packed within the pyrenoid, with ∼15 nm between their centers. Thylakoid stacks and the pyrenoid were connected by cylindrical pyrenoid tubules, physically bridging the sites of light-dependent photosynthesis and light-independent carbon fixation. Multiple parallel minitubules were bundled within each pyrenoid tubule, possibly serving as conduits for the targeted one-dimensional diffusion of small molecules such as ATP and sugars between the chloroplast stroma and the pyrenoid matrix. DOI:http://dx.doi.org/10.7554/eLife.04889.001 Many organisms can harvest light to produce their own energy through a process called photosynthesis. In plant and algal cells, photosynthesis takes place within the chloroplasts, which are compartments that contain stacks of structures called thylakoids. Inside the thylakoids, proteins absorb energy from light and convert it into biochemical energy that can be used by the cell. This energy then powers a series of reactions that result in carbon dioxide being incorporated into energy-rich sugars. The enzyme RuBisCO is essential for this process, and is believed to be the most abundant protein on Earth. In land plants, RuBisCO is found throughout the chloroplast, but in algae it is limited to a specialized area called the pyrenoid. Much of our current knowledge of chloroplast structure comes from transmission electron microscopy (TEM) images. However, the traditional methods used to prepare cells for TEM can damage their internal structures. Also, previous studies have focused primarily on the chloroplasts of land plants, even though aquatic organisms—including the alga Chlamydomonas—account for over 50% of photosynthesis on the planet. Here, Engel et al. provide the first three-dimensional structures of Chlamydomonas chloroplasts in their natural state. They used several recently-developed techniques to study cells that were preserved in a close-to-living condition. The cells were rapidly frozen, thinned with a technique called cryo-focused ion beam milling, and then imaged by a type of TEM called cryo-electron tomography. The three-dimensional images provide many insights into the Chlamydomonas chloroplast, including evidence that lipids and proteins move between the membrane that surrounds the chloroplast—called the chloroplast envelope—and the tips of the thylakoids. These images show how thylakoids may be built by the transport of molecules from the chloroplast envelope. In addition, the images reveal the detailed structures of the tubes that connect the thylakoids to the pyrenoid, which could explain how the two stages of photosynthesis (light harvesting and the conversion of carbon dioxide) can be coordinated even though they occur at different places within the chloroplast. Engel et al. also observed that RuBisCO enzymes are arranged in a hexagonal pattern inside the pyrenoid, but are spaced too far apart to make direct contact with each other. To understand how the pyrenoid is assembled, a future goal will be to determine what causes RuBisCO to be arranged in this way. DOI:http://dx.doi.org/10.7554/eLife.04889.002
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Affiliation(s)
- Benjamin D Engel
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Miroslava Schaffer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Luis Kuhn Cuellar
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Elizabeth Villa
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
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