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Marulanda Valencia W, Pandit A. Photosystem II Subunit S (PsbS): A Nano Regulator of Plant Photosynthesis. J Mol Biol 2024; 436:168407. [PMID: 38109993 DOI: 10.1016/j.jmb.2023.168407] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/26/2023] [Accepted: 12/13/2023] [Indexed: 12/20/2023]
Abstract
Light is required for photosynthesis, but plants are often exposed to excess light, which can lead to photodamage and eventually cell death. To prevent this, they evolved photoprotective feedback mechanisms that regulate photosynthesis and trigger processes that dissipate light energy as heat, called non-photochemical quenching (NPQ). In excess light conditions, the light reaction and activity of Photosystem II (PSII) generates acidification of the thylakoid lumen, which is sensed by special pH-sensitive proteins called Photosystem II Subunit S (PsbS), actuating a photoprotective "switch" in the light-harvesting antenna. Despite its central role in regulating photosynthetic energy conversion, the molecular mechanism of PsbS as well as its interaction with partner proteins are not well understood. This review summarizes the current knowledge on the molecular structure and mechanistic aspects of the light-stress sensor PsbS and addresses open questions and challenges in the field regarding a full understanding of its functional mechanism and role in NPQ.
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Affiliation(s)
| | - Anjali Pandit
- Leiden Inst. of Chemistry, Gorlaeus Laboratory, Einsteinweg 55, 2300 RA Leiden, The Netherlands.
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2
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Li DH, Wilson S, Mastroianni G, Ruban AV. Altered lipid acyl chain length controls energy dissipation in light-harvesting complex II proteoliposomes by hydrophobic mismatch. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2023; 246:112758. [PMID: 37531665 DOI: 10.1016/j.jphotobiol.2023.112758] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 08/04/2023]
Abstract
In plants, the major light-harvesting antenna complex (LHCII) is vital for both light harvesting and photoprotection in photosystem II. Previously, we proposed that the thylakoid membrane itself could switch LHCII into the photoprotective state, qE, via a process known as hydrophobic mismatch. The decrease in the membrane thickness that followed the formation of ΔpH was a key fact that prompted this idea. To test this, we made proteoliposomes from lipids with altered acyl chain length (ACL). Here, we show that ACL regulates the average chlorophyll fluorescence lifetime of LHCII. For liposomes made of lipids with an ACL of 18 carbons, the lifetime was ∼2 ns, like that for the thylakoid membrane. Furthermore, LHCII appears to be quenched in proteoliposomes with an ACL both shorter and longer than 18 carbons. The proteoliposomes made of short ACL lipids display structural heterogeneity revealing two quenched conformations of LHCII, each having characteristic 77 K fluorescence spectra. One conformation spectrally resembles isolated LHCII aggregates, whilst the other resembles LHCII immobilized in polyacrylamide gels. Overall, the decrease in the ACL appears to produce quenched conformations of LHCII, which renders plausible the idea that the trigger of qE is the hydrophobic mismatch.
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Affiliation(s)
- Dan-Hong Li
- Department of Biochemistry, School of Biological and Behavioural Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
| | - Sam Wilson
- Department of Biochemistry, School of Biological and Behavioural Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
| | - Giulia Mastroianni
- Department of Biochemistry, School of Biological and Behavioural Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
| | - Alexander V Ruban
- Department of Biochemistry, School of Biological and Behavioural Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
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3
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Meredith SA, Yoneda T, Hancock AM, Connell SD, Evans SD, Morigaki K, Adams PG. Model Lipid Membranes Assembled from Natural Plant Thylakoids into 2D Microarray Patterns as a Platform to Assess the Organization and Photophysics of Light-Harvesting Proteins. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006608. [PMID: 33690933 DOI: 10.1002/smll.202006608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/14/2021] [Indexed: 06/12/2023]
Abstract
Natural photosynthetic "thylakoid" membranes found in green plants contain a large network of light-harvesting (LH) protein complexes. Rearrangement of this photosynthetic machinery, laterally within stacked membranes called "grana", alters protein-protein interactions leading to changes in the energy balance within the system. Preparation of an experimentally accessible model system that allows the detailed investigation of these complex interactions can be achieved by interfacing thylakoid membranes and synthetic lipids into a template comprised of polymerized lipids in a 2D microarray pattern on glass surfaces. This paper uses this system to interrogate the behavior of LH proteins at the micro- and nanoscale and assesses the efficacy of this model. A combination of fluorescence lifetime imaging and atomic force microscopy reveals the differences in photophysical state and lateral organization between native thylakoid and hybrid membranes, the mechanism of LH protein incorporation into the developing hybrid membranes, and the nanoscale structure of the system. The resulting model system within each corral is a high-quality supported lipid bilayer that incorporates laterally mobile LH proteins. Photosynthetic activity is assessed in the hybrid membranes versus proteoliposomes, revealing that commonly used photochemical assays to test the electron transfer activity of photosystem II may actually produce false-positive results.
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Affiliation(s)
- Sophie A Meredith
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Takuro Yoneda
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Rokkodaicho 1-1, Nada, Kobe, 657-8501, Japan
| | - Ashley M Hancock
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Simon D Connell
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Stephen D Evans
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Kenichi Morigaki
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Rokkodaicho 1-1, Nada, Kobe, 657-8501, Japan
| | - Peter G Adams
- School of Physics and Astronomy and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
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Nicol L, Croce R. The PsbS protein and low pH are necessary and sufficient to induce quenching in the light-harvesting complex of plants LHCII. Sci Rep 2021; 11:7415. [PMID: 33795805 PMCID: PMC8016914 DOI: 10.1038/s41598-021-86975-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/11/2021] [Indexed: 11/10/2022] Open
Abstract
Photosynthesis is tightly regulated in order to withstand dynamic light environments. Under high light intensities, a mechanism known as non-photochemical quenching (NPQ) dissipates excess excitation energy, protecting the photosynthetic machinery from damage. An obstacle that lies in the way of understanding the molecular mechanism of NPQ is the large gap between in vitro and in vivo studies. On the one hand, the complexity of the photosynthetic membrane makes it challenging to obtain molecular information from in vivo experiments. On the other hand, a suitable in vitro system for the study of quenching is not available. Here we have developed a minimal NPQ system using proteoliposomes. With this, we demonstrate that the combination of low pH and PsbS is both necessary and sufficient to induce quenching in LHCII, the main antenna complex of plants. This proteoliposome system can be further exploited to gain more insight into how PsbS and other factors (e.g. zeaxanthin) influence the quenching mechanism observed in LHCII.
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Affiliation(s)
- Lauren Nicol
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Roberta Croce
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
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Pawlak K, Paul S, Liu C, Reus M, Yang C, Holzwarth AR. On the PsbS-induced quenching in the plant major light-harvesting complex LHCII studied in proteoliposomes. PHOTOSYNTHESIS RESEARCH 2020; 144:195-208. [PMID: 32266611 DOI: 10.1007/s11120-020-00740-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
Non-photochemical quenching (NPQ) in photosynthetic organisms provides the necessary photoprotection that allows them to cope with largely and quickly varying light intensities. It involves deactivation of excited states mainly at the level of the antenna complexes of photosystem II using still largely unknown molecular mechanisms. In higher plants the main contribution to NPQ is the so-called qE-quenching, which can be switched on and off in a few seconds. This quenching mechanism is affected by the low pH-induced activation of the small membrane protein PsbS which interacts with the major light-harvesting complex of photosystem II (LHCII). We are reporting here on a mechanistic study of the PsbS-induced LHCII quenching using ultrafast time-resolved chlorophyll (Chl) fluorescence. It is shown that the PsbS/LHCII interaction in reconstituted proteoliposomes induces highly effective and specific quenching of the LHCII excitation by a factor ≥ 20 via Chl-Chl charge-transfer (CT) state intermediates which are weakly fluorescent. Their characteristics are very broad fluorescence bands pronouncedly red-shifted from the typical unquenched LHCII fluorescence maximum. The observation of PsbS-induced Chl-Chl CT-state emission from LHCII in the reconstituted proteoliposomes is highly reminiscent of the in vivo quenching situation and also of LHCII quenching in vitro in aggregated LHCII, indicating a similar quenching mechanism in all those situations. The PsbS mutant lacking the two proton sensing Glu residues induced significant, but much smaller, quenching than wild type. Added zeaxanthin had only minor effects on the yield of quenching in the proteoliposomes. Overall our study shows that PsbS co-reconstituted with LHCII in liposomes represents an excellent in vitro model system with characteristics that are reflecting closely the in vivo qE-quenching situation.
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Affiliation(s)
- Krzysztof Pawlak
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim, Germany
| | - Suman Paul
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim, Germany
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, 10691, Stockholm, Sweden
| | - Cheng Liu
- Key Laboratory of Plant Resources, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Michael Reus
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim, Germany
| | - Chunhong Yang
- Key Laboratory of Plant Resources, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Alfred R Holzwarth
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim, Germany.
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Perozeni F, Cazzaniga S, Ballottari M. In vitro and in vivo investigation of chlorophyll binding sites involved in non-photochemical quenching in Chlamydomonas reinhardtii. PLANT, CELL & ENVIRONMENT 2019; 42:2522-2535. [PMID: 30997927 PMCID: PMC6767442 DOI: 10.1111/pce.13566] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 04/16/2019] [Indexed: 06/09/2023]
Abstract
Non-photochemical quenching (NPQ) of the light energy absorbed is one of the main photoprotective mechanisms evolved by oxygenic photosynthetic organisms to avoid photodamage, at a cost of reduced photosynthetic efficiency. Tuning of NPQ has been reported as a promising biotechnological strategy to increase productivity in both higher plants and unicellular microalgae. Engineering of NPQ induction requires the comprehension of its molecular mechanism(s), strongly debated in the last three decades with several different models proposed. In this work, the molecular details of NPQ induction was investigated at intramolecular level by in vitro and in vitro site-specific mutagenesis on chlorophyll binding sites of the Light-Harvesting Complex Stress-Related 3 (LHCSR3) protein, the pigment binding complexes identified as the quencher during NPQ induction in the model organism for green algae Chlamydomonas reinhardtii. The results obtained demonstrate a correlation between the quenching activity of LHCSR3 variants in vitro and the NPQ phenotypes observed in vivo. In particular, multiple quenching sites in LHCSR3 cooperatively dissipating the excitation energy were revealed with a peculiar role of Chl 613, a chromophore located a close distance to carotenoid binding site L1.
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Akhtar P, Görföl F, Garab G, Lambrev PH. Dependence of chlorophyll fluorescence quenching on the lipid-to-protein ratio in reconstituted light-harvesting complex II membranes containing lipid labels. Chem Phys 2019. [DOI: 10.1016/j.chemphys.2019.03.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Adams PG, Vasilev C, Hunter CN, Johnson MP. Correlated fluorescence quenching and topographic mapping of Light-Harvesting Complex II within surface-assembled aggregates and lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2018; 1859:1075-1085. [PMID: 29928860 PMCID: PMC6135645 DOI: 10.1016/j.bbabio.2018.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 06/11/2018] [Accepted: 06/15/2018] [Indexed: 01/30/2023]
Abstract
Light-Harvesting Complex II (LHCII) is a chlorophyll-protein antenna complex that efficiently absorbs solar energy and transfers electronic excited states to photosystems I and II. Under excess light intensity LHCII can adopt a photoprotective state in which excitation energy is safely dissipated as heat, a process known as Non-Photochemical Quenching (NPQ). In vivo NPQ is triggered by combinatorial factors including transmembrane ΔpH, PsbS protein and LHCII-bound zeaxanthin, leading to dramatically shortened LHCII fluorescence lifetimes. In vitro, LHCII in detergent solution or in proteoliposomes can reversibly adopt an NPQ-like state, via manipulation of detergent/protein ratio, lipid/protein ratio, pH or pressure. Previous spectroscopic investigations revealed changes in exciton dynamics and protein conformation that accompany quenching, however, LHCII-LHCII interactions have not been extensively studied. Here, we correlated fluorescence lifetime imaging microscopy (FLIM) and atomic force microscopy (AFM) of trimeric LHCII adsorbed to mica substrates and manipulated the environment to cause varying degrees of quenching. AFM showed that LHCII self-assembled onto mica forming 2D-aggregates (25-150 nm width). FLIM determined that LHCII in these aggregates were in a quenched state, with much lower fluorescence lifetimes (~0.25 ns) compared to free LHCII in solution (2.2-3.9 ns). LHCII-LHCII interactions were disrupted by thylakoid lipids or phospholipids, leading to intermediate fluorescent lifetimes (0.6-0.9 ns). To our knowledge, this is the first in vitro correlation of nanoscale membrane imaging with LHCII quenching. Our findings suggest that lipids could play a key role in modulating the extent of LHCII-LHCII interactions within the thylakoid membrane and so the propensity for NPQ activation.
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Affiliation(s)
- Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
| | - Cvetelin Vasilev
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Matthew P Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
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Krishnan M, Moolenaar GF, Gupta KBSS, Goosen N, Pandit A. Large-scale in vitro production, refolding and dimerization of PsbS in different microenvironments. Sci Rep 2017; 7:15200. [PMID: 29123155 PMCID: PMC5680255 DOI: 10.1038/s41598-017-15068-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/17/2017] [Indexed: 11/09/2022] Open
Abstract
Plants adapt to fluctuating light conditions by a process called non-photochemical quenching (NPQ), where membrane protein PsbS plays a crucial role and transforms a change in the pH-gradient across the thylakoid membrane under excess light conditions into a photoprotective state, leading to de-excitation of antenna chlorophylls. The PsbS activation mechanism is elusive and has been proposed to involve a monomerization step and protonation of specific residues. To elucidate its function, it is essential to produce PsbS in large quantities, stabilize PsbS in a membrane-mimicking environment and analyze its pH-dependent conformational structure. We present an approach for large-scale in-vitro production and spectroscopic characterization of PsbS under controlled, non-crystalline conditions. We produced PsbS of the moss Physcomitrella patens in milligram quantities in E. coli, refolded PsbS in several detergent types and analyzed its conformation at neutral and low pH by Dynamic Light Scattering and NMR spectroscopy. Our results reveal that at both pH conditions, PsbS exist as dimers or in apparent monomer-dimer equilibria. Lowering of the pH induces conformational changes, destabilizes the dimer state and shifts the equilibria towards the monomeric form. In vivo, a similar response upon thylakoid lumen acidification may tune PsbS activity in a gradual manner.
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Affiliation(s)
- Maithili Krishnan
- Leiden University, Leiden Institute of Chemistry, Gorlaeus Laboratories, Einsteinweg, 55 2333 CC, Leiden, The Netherlands
| | - Geri F Moolenaar
- Leiden University, Leiden Institute of Chemistry, Gorlaeus Laboratories, Einsteinweg, 55 2333 CC, Leiden, The Netherlands
| | - Karthick Babu Sai Sankar Gupta
- Leiden University, Leiden Institute of Chemistry, Gorlaeus Laboratories, Einsteinweg, 55 2333 CC, Leiden, The Netherlands
| | - Nora Goosen
- Leiden University, Leiden Institute of Chemistry, Gorlaeus Laboratories, Einsteinweg, 55 2333 CC, Leiden, The Netherlands
| | - Anjali Pandit
- Leiden University, Leiden Institute of Chemistry, Gorlaeus Laboratories, Einsteinweg, 55 2333 CC, Leiden, The Netherlands.
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Natali A, Gruber JM, Dietzel L, Stuart MCA, van Grondelle R, Croce R. Light-harvesting Complexes (LHCs) Cluster Spontaneously in Membrane Environment Leading to Shortening of Their Excited State Lifetimes. J Biol Chem 2016; 291:16730-9. [PMID: 27252376 DOI: 10.1074/jbc.m116.730101] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Indexed: 11/06/2022] Open
Abstract
The light reactions of photosynthesis, which include light-harvesting and charge separation, take place in the amphiphilic environment of the thylakoid membrane. The light-harvesting complex II (LHCII) is the main responsible for light absorption in plants and green algae and is involved in photoprotective mechanisms that regulate the amount of excited states in the membrane. The dual function of LHCII has been extensively studied in detergent micelles, but recent results have indicated that the properties of this complex differ in a lipid environment. In this work we checked these suggestions by studying LHCII in liposomes. By combining bulk and single molecule measurements, we monitored the fluorescence characteristics of liposomes containing single complexes up to densely packed proteoliposomes. We show that the natural lipid environment per se does not alter the properties of LHCII, which for single complexes remain very similar to that in detergent. However, we show that LHCII has the strong tendency to cluster in the membrane and that protein interactions and the extent of crowding modulate the lifetimes of the excited state in the membrane. Finally, the presence of LHCII monomers at low concentrations of complexes per liposome is discussed.
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Affiliation(s)
- Alberto Natali
- From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - J Michael Gruber
- From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Lars Dietzel
- Institute of Molecular Biosciences, Goethe-University Frankfurt/M, 60438 Frankfurt, Germany, and
| | - Marc C A Stuart
- Electron Microscopy, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Rienk van Grondelle
- From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Roberta Croce
- From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands,
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