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Flannery SE, Hepworth C, Wood WHJ, Pastorelli F, Hunter CN, Dickman MJ, Jackson PJ, Johnson MP. Developmental acclimation of the thylakoid proteome to light intensity in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:223-244. [PMID: 33118270 PMCID: PMC7898487 DOI: 10.1111/tpj.15053] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/13/2020] [Accepted: 10/21/2020] [Indexed: 05/03/2023]
Abstract
Photosynthetic acclimation, the ability to adjust the composition of the thylakoid membrane to optimise the efficiency of electron transfer to the prevailing light conditions, is crucial to plant fitness in the field. While much is known about photosynthetic acclimation in Arabidopsis, to date there has been no study that combines both quantitative label-free proteomics and photosynthetic analysis by gas exchange, chlorophyll fluorescence and P700 absorption spectroscopy. Using these methods we investigated how the levels of 402 thylakoid proteins, including many regulatory proteins not previously quantified, varied upon long-term (weeks) acclimation of Arabidopsis to low (LL), moderate (ML) and high (HL) growth light intensity and correlated these with key photosynthetic parameters. We show that changes in the relative abundance of cytb6 f, ATP synthase, FNR2, TIC62 and PGR6 positively correlate with changes in estimated PSII electron transfer rate and CO2 assimilation. Improved photosynthetic capacity in HL grown plants is paralleled by increased cyclic electron transport, which positively correlated with NDH, PGRL1, FNR1, FNR2 and TIC62, although not PGR5 abundance. The photoprotective acclimation strategy was also contrasting, with LL plants favouring slowly reversible non-photochemical quenching (qI), which positively correlated with LCNP, while HL plants favoured rapidly reversible quenching (qE), which positively correlated with PSBS. The long-term adjustment of thylakoid membrane grana diameter positively correlated with LHCII levels, while grana stacking negatively correlated with CURT1 and RIQ protein abundance. The data provide insights into how Arabidopsis tunes photosynthetic electron transfer and its regulation during developmental acclimation to light intensity.
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Affiliation(s)
- Sarah E. Flannery
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldFirth CourtWestern BankSheffieldUK
| | - Christopher Hepworth
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldFirth CourtWestern BankSheffieldUK
| | - William H. J. Wood
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldFirth CourtWestern BankSheffieldUK
| | - Federica Pastorelli
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldFirth CourtWestern BankSheffieldUK
| | - Christopher N. Hunter
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldFirth CourtWestern BankSheffieldUK
| | - Mark J. Dickman
- Department of Chemical and Biological EngineeringChELSI InstituteUniversity of SheffieldSheffieldUK
| | - Philip J. Jackson
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldFirth CourtWestern BankSheffieldUK
- Department of Chemical and Biological EngineeringChELSI InstituteUniversity of SheffieldSheffieldUK
| | - Matthew P. Johnson
- Department of Molecular Biology and BiotechnologyUniversity of SheffieldFirth CourtWestern BankSheffieldUK
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2
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Abstract
A universal design principle underlies photosynthetic antenna systems
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Affiliation(s)
- Christopher D P Duffy
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
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3
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Saccon F, Giovagnetti V, Shukla MK, Ruban AV. Rapid regulation of photosynthetic light harvesting in the absence of minor antenna and reaction centre complexes. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3626-3637. [PMID: 32149343 PMCID: PMC7307847 DOI: 10.1093/jxb/eraa126] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/02/2020] [Indexed: 05/25/2023]
Abstract
Plants are subject to dramatic fluctuations in the intensity of sunlight throughout the day. When the photosynthetic machinery is exposed to high light, photons are absorbed in excess, potentially leading to oxidative damage of its delicate membrane components. A photoprotective molecular process called non-photochemical quenching (NPQ) is the fastest response carried out in the thylakoid membranes to harmlessly dissipate excess light energy. Despite having been intensely studied, the site and mechanism of this essential regulatory process are still debated. Here, we show that the main NPQ component called energy-dependent quenching (qE) is present in plants with photosynthetic membranes largely enriched in the major trimeric light-harvesting complex (LHC) II, while being deprived of all minor LHCs and most photosystem core proteins. This fast and reversible quenching depends upon thylakoid lumen acidification (ΔpH). Enhancing ΔpH amplifies the extent of the quenching and restores qE in the membranes lacking PSII subunit S protein (PsbS), whereas the carotenoid zeaxanthin modulates the kinetics and amplitude of the quenching. These findings highlight the self-regulatory properties of the photosynthetic light-harvesting membranes in vivo, where the ability to switch reversibly between the harvesting and dissipative states is an intrinsic property of the major LHCII.
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Affiliation(s)
- Francesco Saccon
- Queen Mary University of London, School of Biological and Chemical Sciences, London, UK
| | - Vasco Giovagnetti
- Queen Mary University of London, School of Biological and Chemical Sciences, London, UK
| | - Mahendra K Shukla
- Queen Mary University of London, School of Biological and Chemical Sciences, London, UK
| | - Alexander V Ruban
- Queen Mary University of London, School of Biological and Chemical Sciences, London, UK
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4
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Grebe S, Trotta A, Bajwa AA, Suorsa M, Gollan PJ, Jansson S, Tikkanen M, Aro EM. The unique photosynthetic apparatus of Pinaceae: analysis of photosynthetic complexes in Picea abies. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:3211-3225. [PMID: 30938447 PMCID: PMC6598058 DOI: 10.1093/jxb/erz127] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/13/2019] [Indexed: 05/07/2023]
Abstract
Pinaceae are the predominant photosynthetic species in boreal forests, but so far no detailed description of the protein components of the photosynthetic apparatus of these gymnosperms has been available. In this study we report a detailed characterization of the thylakoid photosynthetic machinery of Norway spruce (Picea abies (L.) Karst). We first customized a spruce thylakoid protein database from translated transcript sequences combined with existing protein sequences derived from gene models, which enabled reliable tandem mass spectrometry identification of P. abies thylakoid proteins from two-dimensional large pore blue-native/SDS-PAGE. This allowed a direct comparison of the two-dimensional protein map of thylakoid protein complexes from P. abies with the model angiosperm Arabidopsis thaliana. Although the subunit composition of P. abies core PSI and PSII complexes is largely similar to that of Arabidopsis, there was a high abundance of a smaller PSI subcomplex, closely resembling the assembly intermediate PSI* complex. In addition, the evolutionary distribution of light-harvesting complex (LHC) family members of Pinaceae was compared in silico with other land plants, revealing that P. abies and other Pinaceae (also Gnetaceae and Welwitschiaceae) have lost LHCB4, but retained LHCB8 (formerly called LHCB4.3). The findings reported here show the composition of the photosynthetic apparatus of P. abies and other Pinaceae members to be unique among land plants.
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Affiliation(s)
- Steffen Grebe
- Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
| | - Andrea Trotta
- Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
| | - Azfar A Bajwa
- Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
| | - Marjaana Suorsa
- Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
| | - Peter J Gollan
- Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
| | - Stefan Jansson
- Umeå University, Faculty of Science and Technology, Department of Plant Physiology, Umeå Plant Science Centre (UPSC), Umeå, Sweden
| | - Mikko Tikkanen
- Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
| | - Eva-Mari Aro
- Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland
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5
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Osmond B, Chow WS, Pogson BJ, Robinson SA. Probing functional and optical cross-sections of PSII in leaves during state transitions using fast repetition rate light induced fluorescence transients. FUNCTIONAL PLANT BIOLOGY : FPB 2019; 46:567-583. [PMID: 32172734 DOI: 10.1071/fp18054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 02/07/2019] [Indexed: 05/11/2023]
Abstract
Plants adjust the relative sizes of PSII and PSI antennae in response to the spectral composition of weak light favouring either photosystem by processes known as state transitions (ST), attributed to a discrete antenna migration involving phosphorylation of light-harvesting chlorophyll-protein complexes in PSII. Here for the first time we monitored the extent and dynamics of ST in leaves from estimates of optical absorption cross-section (relative PSII antenna size; aPSII). These estimates were obtained from in situ measurements of functional absorption cross-section (σPSII) and maximum photochemical efficiency of PSII (φPSII); i.e. aPSII = σPSII/φPSII (Kolber et al. 1998) and other parameters from a light induced fluorescence transient (LIFT) device (Osmond et al. 2017). The fast repetition rate (FRR) QA flash protocol of this instrument monitors chlorophyll fluorescence yields with reduced QA irrespective of the redox state of plastoquinone (PQ), as well as during strong ~1 s white light pulses that fully reduce the PQ pool. Fitting this transient with the FRR model monitors kinetics of PSII → PQ, PQ → PSI, and the redox state of the PQ pool in the 'PQ pool control loop' that underpins ST, with a time resolution of a few seconds. All LIFT/FRR criteria confirmed the absence of ST in antenna mutant chlorina-f2 of barley and asLhcb2-12 of Arabidopsis, as well as STN7 kinase mutants stn7 and stn7/8. In contrast, wild-type barley and Arabidopsis genotypes Col, npq1, npq4, OEpsbs, pgr5 bkg and pgr5, showed normal ST. However, the extent of ST (and by implication the size of the phosphorylated LHCII pool participating in ST) deduced from changes in a'PSII and other parameters with reduced QA range up to 35%. Estimates from strong WL pulses in the same assay were only ~10%. The larger estimates of ST from the QA flash are discussed in the context of contemporary dynamic structural models of ST involving formation and participation of PSII and PSI megacomplexes in an 'energetically connected lake' of phosphorylated LHCII trimers (Grieco et al. 2015). Despite the absence of ST, asLhcb2-12 displays normal wild-type modulation of electron transport rate (ETR) and the PQ pool during ST assays, reflecting compensatory changes in antenna LHCIIs in this genotype. Impaired LHCII phosphorylation in stn7 and stn7/8 accelerates ETR from PSII →PQ, over-reducing the PQ pool and abolishing the yield difference between the QA flash and WL pulse, with implications for photochemical and thermal phases of the O-J-I-P transient.
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Affiliation(s)
- Barry Osmond
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia; and Division of Plant Sciences, Research School of Biology, The Australian National University, 46 Sullivan's Creek Road, Acton, ACT 2601, Australia; and Corresponding author.
| | - Wah Soon Chow
- Division of Plant Sciences, Research School of Biology, The Australian National University, 46 Sullivan's Creek Road, Acton, ACT 2601, Australia
| | - Barry J Pogson
- Division of Plant Sciences, Research School of Biology, The Australian National University, 46 Sullivan's Creek Road, Acton, ACT 2601, Australia
| | - Sharon A Robinson
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
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6
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Townsend AJ, Ware MA, Ruban AV. Dynamic interplay between photodamage and photoprotection in photosystem II. PLANT, CELL & ENVIRONMENT 2018; 41:1098-1112. [PMID: 29210070 DOI: 10.1111/pce.13107] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 06/07/2023]
Abstract
Photoinhibition is the light-induced reduction in photosynthetic efficiency and is usually associated with damage to the D1 photosystem II (PSII) reaction centre protein. This damage must either be repaired, through the PSII repair cycle, or prevented in the first place by nonphotochemical quenching (NPQ). Both NPQ and D1 repair contribute to light tolerance because they ensure the long-term maintenance of the highest quantum yield of PSII. However, the relative contribution of each of these processes is yet to be elucidated. The application of a pulse amplitude modulation fluorescence methodology, called protective NPQ, enabled us to evaluate of the protective effectiveness of the processes. Within this study, the contribution of NPQ and D1 repair to the photoprotective capacity of Arabidopsis thaliana was elucidated by using inhibitors and mutants known to affect each process. We conclude that NPQ contributes a greater amount to the maintenance of a high PSII yield than D1 repair under short periods of illumination. This research further supports the role of protective components of NPQ during light fluctuations and the value of protective NPQ and qPd as unambiguous fluorescence parameters, as opposed to qI and Fv /Fm , for quantifying photoinactivation of reaction centre II and light tolerance of photosynthetic organisms.
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Affiliation(s)
- Alexandra J Townsend
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E14NS, UK
| | - Maxwell A Ware
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E14NS, UK
| | - Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E14NS, UK
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7
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Townsend AJ, Saccon F, Giovagnetti V, Wilson S, Ungerer P, Ruban AV. The causes of altered chlorophyll fluorescence quenching induction in the Arabidopsis mutant lacking all minor antenna complexes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:666-675. [PMID: 29548769 DOI: 10.1016/j.bbabio.2018.03.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/01/2018] [Accepted: 03/10/2018] [Indexed: 01/18/2023]
Abstract
Non-photochemical quenching (NPQ) of chlorophyll fluorescence is the process by which excess light energy is harmlessly dissipated within the photosynthetic membrane. The fastest component of NPQ, known as energy-dependent quenching (qE), occurs within minutes, but the site and mechanism of qE remain of great debate. Here, the chlorophyll fluorescence of Arabidopsis thaliana wild type (WT) plants was compared to mutants lacking all minor antenna complexes (NoM). Upon illumination, NoM exhibits altered chlorophyll fluorescence quenching induction (i.e. from the dark-adapted state) characterised by three different stages: (i) a fast quenching component, (ii) transient fluorescence recovery and (iii) a second quenching component. The initial fast quenching component originates in light harvesting complex II (LHCII) trimers and is dependent upon PsbS and the formation of a proton gradient across the thylakoid membrane (ΔpH). Transient fluorescence recovery is likely to occur in both WT and NoM plants, but it cannot be overcome in NoM due to impaired ΔpH formation and a reduced zeaxanthin synthesis rate. Moreover, an enhanced fluorescence emission peak at ~679 nm in NoM plants indicates detachment of LHCII trimers from the bulk antenna system, which could also contribute to the transient fluorescence recovery. Finally, the second quenching component is triggered by both ΔpH and PsbS and enhanced by zeaxanthin synthesis. This study indicates that minor antenna complexes are not essential for qE, but reveals their importance in electron stransport, ΔpH formation and zeaxanthin synthesis.
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Affiliation(s)
- Alexandra J Townsend
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK
| | - Francesco Saccon
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK
| | - Vasco Giovagnetti
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK
| | - Sam Wilson
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK
| | - Petra Ungerer
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK
| | - Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK.
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8
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Belgio E, Trsková E, Kotabová E, Ewe D, Prášil O, Kaňa R. High light acclimation of Chromera velia points to photoprotective NPQ. PHOTOSYNTHESIS RESEARCH 2018; 135:263-274. [PMID: 28405863 DOI: 10.1007/s11120-017-0385-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/06/2017] [Indexed: 05/13/2023]
Abstract
It has previously been shown that the long-term treatment of Arabidopsis thaliana with the chloroplast inhibitor lincomycin leads to photosynthetic membranes enriched in antennas, strongly reduced in photosystem II reaction centers (PSII) and with enhanced nonphotochemical quenching (NPQ) (Belgio et al. Biophys J 102:2761-2771, 2012). Here, a similar physiological response was found in the microalga Chromera velia grown under high light (HL). In comparison to cells acclimated to low light, HL cells displayed a severe re-organization of the photosynthetic membrane characterized by (1) a reduction of PSII but similar antenna content; (2) partial uncoupling of antennas from PSII; (3) enhanced NPQ. The decrease in the number of PSII represents a rather unusual acclimation response compared to other phototrophs, where a smaller PSII antenna size is more commonly found under high light. Despite the diminished PSII content, no net damage could be detected on the basis of the Photosynthesis versus irradiance curve and electron transport rates pointing at the excess capacity of PSII. We therefore concluded that the photoinhibition is minimized under high light by a lower PSII content and that cells are protected by NPQ in the antennas.
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Affiliation(s)
- Erica Belgio
- Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81, Třeboň, Czech Republic.
| | - Eliška Trsková
- Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 31, 37005, Czech Budejovice, Czech Republic
| | - Eva Kotabová
- Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81, Třeboň, Czech Republic
| | - Daniela Ewe
- Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81, Třeboň, Czech Republic
| | - Ondřej Prášil
- Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 31, 37005, Czech Budejovice, Czech Republic
| | - Radek Kaňa
- Centre Algatech, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 31, 37005, Czech Budejovice, Czech Republic
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9
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Sacharz J, Giovagnetti V, Ungerer P, Mastroianni G, Ruban AV. The xanthophyll cycle affects reversible interactions between PsbS and light-harvesting complex II to control non-photochemical quenching. NATURE PLANTS 2017; 3:16225. [PMID: 28134919 DOI: 10.1038/nplants.2016.225] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/22/2016] [Indexed: 05/19/2023]
Abstract
To maintain high photosynthetic rates, plants must adapt to their light environment on a timescale of seconds to minutes. Therefore, the light-harvesting antenna system of photosystem II in thylakoid membranes, light-harvesting complex II (LHCII), has a feedback mechanism, which determines the proportion of absorbed energy dissipated as heat: non-photochemical chlorophyll fluorescence quenching (NPQ). This is crucial to prevent photo-oxidative damage to photosystem II (PSII) and is controlled by the transmembrane pH differences (ΔpH). High ΔpH activates NPQ by protonation of the protein PsbS and the enzymatic de-epoxidation of LHCII-bound violaxanthin to zeaxanthin. But the precise role of PsbS and its interactions with different LHCII complexes remain uncertain. We have investigated PsbS-LHCII interactions in native thylakoid membranes using magnetic-bead-linked antibody pull-downs. The interaction of PsbS with the antenna system is affected by both ΔpH and the level of zeaxanthin. In the presence of ΔpH alone, PsbS is found to be mainly associated with the trimeric LHCII protein polypeptides, Lhcb1, Lhcb2 and Lhcb3. However, a combination of ΔpH and zeaxanthin increases the proportion of PsbS bound to the minor LHCII antenna complex proteins Lhcb4, Lhcb5 and Lhcb6. This pattern of interaction is not influenced by the presence of PSII reactions centres. Similar to LHCII particles in the photosynthetic membrane, PsbS protein forms clusters in the NPQ state. NPQ recovery in the dark requires uncoupling of PsbS. We suggest that PsbS acts as a 'seeding' centre for the LHCII antenna rearrangement that is involved in NPQ.
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Affiliation(s)
- Joanna Sacharz
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Vasco Giovagnetti
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Petra Ungerer
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Giulia Mastroianni
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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10
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Ware MA, Belgio E, Ruban AV. Photoprotective capacity of non-photochemical quenching in plants acclimated to different light intensities. PHOTOSYNTHESIS RESEARCH 2015; 126:261-74. [PMID: 25702085 DOI: 10.1007/s11120-015-0102-4] [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: 11/28/2014] [Accepted: 02/15/2015] [Indexed: 05/20/2023]
Abstract
Arabidopsis plants grown at low light were exposed to a gradually increasing actinic light routine. This method allows for the discerning of the photoprotective component of NPQ, pNPQ and photoinhibition. They exhibited lower values of Photosystem II (PSII) yield in comparison to high-light grown plants, and higher calculated dark fluorescence level (F'o calc.) than the measured one (F'o act.). As a result, in low-light grown plants, the values of qP measured in the dark appeared higher than 1. Normally, F'o act. and F'o calc. match well at moderate light intensities but F'o act. becomes higher at increasing intensities due to reaction centre (RCII) damage; this indicates the onset of photoinhibition. To explain the unusual increase of qP in the dark in low-light grown plants, we have undertaken an analysis of PSII antenna size using biochemical and spectroscopic approaches. Sucrose gradient separation of thylakoid membrane complexes and fast fluorescence induction experiments illustrated that the relative PSII cross section does not increase appreciably with the rise in PSII antenna size in the low-light grown plants. This suggests that part of the increased LHCII antenna is less efficiently coupled to the RCII. A model based upon the existence of an uncoupled population LHCII is proposed to explain the discrepancies in calculated and measured values of F'o.
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Affiliation(s)
- Maxwell A Ware
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Erica Belgio
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
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11
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Horn A, Hennig J, Ahmed YL, Stier G, Wild K, Sattler M, Sinning I. Structural basis for cpSRP43 chromodomain selectivity and dynamics in Alb3 insertase interaction. Nat Commun 2015; 6:8875. [PMID: 26568381 PMCID: PMC4660199 DOI: 10.1038/ncomms9875] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/12/2015] [Indexed: 01/21/2023] Open
Abstract
Canonical membrane protein biogenesis requires co-translational delivery of ribosome-associated proteins to the Sec translocase and depends on the signal recognition particle (SRP) and its receptor (SR). In contrast, high-throughput delivery of abundant light-harvesting chlorophyll a,b-binding proteins (LHCPs) in chloroplasts to the Alb3 insertase occurs post-translationally via a soluble transit complex including the cpSRP43/cpSRP54 heterodimer (cpSRP). Here we describe the molecular mechanisms of tethering cpSRP to the Alb3 insertase by specific interaction of cpSRP43 chromodomain 3 with a linear motif in the Alb3 C-terminal tail. Combining NMR spectroscopy, X-ray crystallography and biochemical analyses, we dissect the structural basis for selectivity of chromodomains 2 and 3 for their respective ligands cpSRP54 and Alb3, respectively. Negative cooperativity in ligand binding can be explained by dynamics in the chromodomain interface. Our study provides a model for membrane recruitment of the transit complex and may serve as a prototype for a functional gain by the tandem arrangement of chromodomains. The chloroplast signal recognition particle delivers LHCPs to the thylakoid membrane by interaction of cpSRP43 with the Alb3 insertase. Here the authors decipher the specific recognition of the Alb3 C-terminal tail within the interface of two communicating chromodomains by structural biochemistry.
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Affiliation(s)
- Annemarie Horn
- Heidelberg University Biochemistry Center (BZH), INF 328, Heidelberg D-69120, Germany
| | - Janosch Hennig
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstrasse 4, Garching DE-85747, Germany.,Institute of Structural Biology, Helmholtz Center Munich, Ingolstädter Landstrasse 1, Neuherberg D-85764, Germany
| | - Yasar L Ahmed
- Heidelberg University Biochemistry Center (BZH), INF 328, Heidelberg D-69120, Germany
| | - Gunter Stier
- Heidelberg University Biochemistry Center (BZH), INF 328, Heidelberg D-69120, Germany
| | - Klemens Wild
- Heidelberg University Biochemistry Center (BZH), INF 328, Heidelberg D-69120, Germany
| | - Michael Sattler
- Center for Integrated Protein Science Munich at Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Lichtenbergstrasse 4, Garching DE-85747, Germany.,Institute of Structural Biology, Helmholtz Center Munich, Ingolstädter Landstrasse 1, Neuherberg D-85764, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), INF 328, Heidelberg D-69120, Germany
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12
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Belgio E, Ungerer P, Ruban AV. Light-harvesting superstructures of green plant chloroplasts lacking photosystems. PLANT, CELL & ENVIRONMENT 2015; 38:2035-47. [PMID: 25737144 DOI: 10.1111/pce.12528] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/23/2015] [Indexed: 05/26/2023]
Abstract
The light-harvesting antenna of higher plant photosystem II (LHCII) is the major photosynthetic membrane component encoded by an entire family of homologous nuclear genes. On the contrary, the great majority of proteins of photosystems and electron transport components are encoded by the chloroplast genome. In this work, we succeeded in gradually inhibiting the expression of the chloroplast genes that led to the disappearance of the photosystem complexes, mimicking almost total photoinhibition. The treated plants, despite displaying only some early signs of senescence, sustained their metabolism and growth for several weeks. The only major remaining membrane component was LHCII antenna that formed superstructures - stacks of dozens of thylakoids or supergrana. Freeze-fracture electron microscopy revealed specific organization, directly displaying frequently bifurcated membranes with reduced or totally absent photosystem II (PSII) reaction centre complexes. Our findings show that it is possible to accumulate large amounts of light-harvesting membranes, organized into three-dimensional structures, in the absence of reaction centre complexes. This points to the reciprocal role of LHCII and PSII in self-assembly of the three-dimensional matrix of the photosynthetic membrane, dictating its size and flexible adaptation to the light environment.
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Affiliation(s)
- Erica Belgio
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Petra Ungerer
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
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13
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Nelson CJ, Millar AH. Protein turnover in plant biology. NATURE PLANTS 2015; 1:15176. [PMID: 27246884 DOI: 10.1038/nplants.2015.176] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 10/14/2015] [Indexed: 05/20/2023]
Abstract
The protein content of plant cells is constantly being updated. This process is driven by the opposing actions of protein degradation, which defines the half-life of each polypeptide, and protein synthesis. Our understanding of the processes that regulate protein synthesis and degradation in plants has advanced significantly over the past decade. Post-transcriptional modifications that influence features of the mRNA populations, such as poly(A) tail length and secondary structure, contribute to the regulation of protein synthesis. Post-translational modifications such as phosphorylation, ubiquitination and non-enzymatic processes such as nitrosylation and carbonylation, govern the rate of degradation. Regulators such as the plant TOR kinase, and effectors such as the E3 ligases, allow plants to balance protein synthesis and degradation under developmental and environmental change. Establishing an integrated understanding of the processes that underpin changes in protein abundance under various physiological and developmental scenarios will accelerate our ability to model and rationally engineer plants.
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Affiliation(s)
- Clark J Nelson
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Hwy, Crawley 6009, Perth, Western Australia, Australia
| | - A Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Hwy, Crawley 6009, Perth, Western Australia, Australia
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14
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Akhtar P, Dorogi M, Pawlak K, Kovács L, Bóta A, Kiss T, Garab G, Lambrev PH. Pigment interactions in light-harvesting complex II in different molecular environments. J Biol Chem 2015; 290:4877-4886. [PMID: 25525277 PMCID: PMC4335227 DOI: 10.1074/jbc.m114.607770] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/16/2014] [Indexed: 11/06/2022] Open
Abstract
Extraction of plant light-harvesting complex II (LHCII) from the native thylakoid membrane or from aggregates by the use of surfactants brings about significant changes in the excitonic circular dichroism (CD) spectrum and fluorescence quantum yield. To elucidate the cause of these changes, e.g. trimer-trimer contacts or surfactant-induced structural perturbations, we compared the CD spectra and fluorescence kinetics of LHCII aggregates, artificial and native LHCII-lipid membranes, and LHCII solubilized in different detergents or trapped in polymer gel. By this means we were able to identify CD spectral changes specific to LHCII-LHCII interactions, at (-)-437 and (+)-484 nm, and changes specific to the interaction with the detergent n-dodecyl-β-maltoside (β-DM) or membrane lipids, at (+)-447 and (-)-494 nm. The latter change is attributed to the conformational change of the LHCII-bound carotenoid neoxanthin, by analyzing the CD spectra of neoxanthin-deficient plant thylakoid membranes. The neoxanthin-specific band at (-)-494 nm was not pronounced in LHCII in detergent-free gels or solubilized in the α isomer of DM but was present when LHCII was reconstituted in membranes composed of phosphatidylcholine or plant thylakoid lipids, indicating that the conformation of neoxanthin is sensitive to the molecular environment. Neither the aggregation-specific CD bands, nor the surfactant-specific bands were positively associated with the onset of fluorescence quenching, which could be triggered without invoking such spectral changes. Significant quenching was not active in reconstituted LHCII proteoliposomes, whereas a high degree of energetic connectivity, depending on the lipid:protein ratio, in these membranes allows for efficient light harvesting.
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Affiliation(s)
- Parveen Akhtar
- Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged and
| | - Márta Dorogi
- Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged and
| | - Krzysztof Pawlak
- Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged and
| | - László Kovács
- Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged and
| | - Attila Bóta
- Hungarian Academy of Sciences, Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Magyar tudósok körútja 2, 1117 Budapest, Hungary
| | - Teréz Kiss
- Hungarian Academy of Sciences, Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Magyar tudósok körútja 2, 1117 Budapest, Hungary
| | - Győző Garab
- Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged and
| | - Petar H Lambrev
- Hungarian Academy of Sciences, Biological Research Centre, Temesvári krt. 62, 6726 Szeged and.
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15
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Economic photoprotection in photosystem II that retains a complete light-harvesting system with slow energy traps. Nat Commun 2014; 5:4433. [PMID: 25014663 DOI: 10.1038/ncomms5433] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 06/18/2014] [Indexed: 11/08/2022] Open
Abstract
The light-harvesting antenna of higher plant photosystem II has an intrinsic capability for self-defence against intense sunlight. The thermal dissipation of excess energy can be measured as the non-photochemical quenching of chlorophyll fluorescence. It has recently been proposed that the transition between the light-harvesting and self-defensive modes is associated with a reorganization of light-harvesting complexes. Here we show that despite structural changes, the photosystem II cross-section does not decrease. Our study reveals that the efficiency of energy trapping by the non-photochemical quencher(s) is lower than the efficiency of energy capture by the reaction centres. Consequently, the photoprotective mechanism works effectively for closed rather than open centres. This type of defence preserves the exceptional efficiency of electron transport in a broad range of light intensities, simultaneously ensuring high photosynthetic productivity and, under hazardous light conditions, sufficient photoprotection for both the reaction centre and the light-harvesting pigments of the antenna.
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16
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Johnson MP, Vasilev C, Olsen JD, Hunter CN. Nanodomains of cytochrome b6f and photosystem II complexes in spinach grana thylakoid membranes. THE PLANT CELL 2014; 26:3051-61. [PMID: 25035407 PMCID: PMC4145131 DOI: 10.1105/tpc.114.127233] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/06/2014] [Accepted: 06/24/2014] [Indexed: 05/18/2023]
Abstract
The cytochrome b6f (cytb6f) complex plays a central role in photosynthesis, coupling electron transport between photosystem II (PSII) and photosystem I to the generation of a transmembrane proton gradient used for the biosynthesis of ATP. Photosynthesis relies on rapid shuttling of electrons by plastoquinone (PQ) molecules between PSII and cytb6f complexes in the lipid phase of the thylakoid membrane. Thus, the relative membrane location of these complexes is crucial, yet remains unknown. Here, we exploit the selective binding of the electron transfer protein plastocyanin (Pc) to the lumenal membrane surface of the cytb6f complex using a Pc-functionalized atomic force microscope (AFM) probe to identify the position of cytb6f complexes in grana thylakoid membranes from spinach (Spinacia oleracea). This affinity-mapping AFM method directly correlates membrane surface topography with Pc-cytb6f interactions, allowing us to construct a map of the grana thylakoid membrane that reveals nanodomains of colocalized PSII and cytb6f complexes. We suggest that the close proximity between PSII and cytb6f complexes integrates solar energy conversion and electron transfer by fostering short-range diffusion of PQ in the protein-crowded thylakoid membrane, thereby optimizing photosynthetic efficiency.
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Affiliation(s)
- Matthew P Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Cvetelin Vasilev
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - John D Olsen
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
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17
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Trans-thylakoid ∆pH dependent oscillation of F(PSI)/F(PSII) under continuous irradiance in isolated thylakoids. J Bioenerg Biomembr 2013; 46:71-82. [PMID: 24214386 DOI: 10.1007/s10863-013-9533-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 10/10/2013] [Indexed: 10/26/2022]
Abstract
Energy distribution between photosystems (PSI & PSII) under prolonged and continuous white light irradiance was assessed by monitoring the progress of their fluorescence emission (FPSI/FPSII) at 77 K. Our observations indicate FPSI/FPSII to oscillate with the progress of irradiance treatments at all intensities tested (100, 200, 500, and 800 μE m(-2) S(-1)). The amplitude of the oscillation increased with the progress, whereas the periodicity of the oscillation increased with the intensity of the incident irradiance. Spectral analysis indicated fluctuation of FPSI to be the major determinant of the observed oscillation. The first rise and fall of FPSI/FPSII overlapped with phosphorylation and dephosphorylation of LHCII, but oscillation of FPSI/FPSII continued for several cycles without any further phosphorylation of LHCII. Moreover, in presence of DCMU where linear electron flow (LEF) is suppressed and LHCII phosphorylation is completely abolished, the oscillation of FPSI/FPSII was not abolished. These data indicated that LHCII phosphorylation was not essential for the observed oscillation of energy distribution between the photosystems. In contrast, in the presence of inhibitors of cyclic electron flow (CEF) like Antimycin A (AA) and rotenone, the oscillation of FPSI/FPSII was either abolished or severely dampened. Additionally, the oscillation was also abolished in presence of uncouplers like NH4Cl and nigericin that cancels the trans-thylakoid ∆pH. Thus, trans-thylakoid ∆pH, generated through CEF, appear to be an important determinant of oscillation of FPSI/FPSII in isolated thylakoids. The phenomenon of oscillation could be associated with a CEF mediated chromatic adaptation of PSI in presence of excess irradiance.
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18
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Ilioaia C, Duffy CDP, Johnson MP, Ruban AV. Changes in the Energy Transfer Pathways within Photosystem II Antenna Induced by Xanthophyll Cycle Activity. J Phys Chem B 2013; 117:5841-7. [DOI: 10.1021/jp402469d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Cristian Ilioaia
- Institut de
Biologie et de Technologie
de Saclay, CEA Saclay, 91191 Gif/Yvette
Cedex, France
| | - Christopher D. P. Duffy
- School of
Biological and Chemical
Sciences, Queen Mary University of London, Mile End, Bancroft Road, London E1 4NS, United Kingdom
| | - Matthew P. Johnson
- Department of Molecular Biology
and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Alexander V. Ruban
- School of
Biological and Chemical
Sciences, Queen Mary University of London, Mile End, Bancroft Road, London E1 4NS, United Kingdom
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19
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Anderson JM, Horton P, Kim EH, Chow WS. Towards elucidation of dynamic structural changes of plant thylakoid architecture. Philos Trans R Soc Lond B Biol Sci 2013; 367:3515-24. [PMID: 23148278 DOI: 10.1098/rstb.2012.0373] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Long-term acclimation of shade versus sun plants modulates the composition, function and structural organization of the architecture of the thylakoid membrane network. Significantly, these changes in the macroscopic structural organization of shade and sun plant chloroplasts during long-term acclimation are also mimicked following rapid transitions in irradiance: reversible ultrastructural changes in the entire thylakoid membrane network increase the number of grana per chloroplast, but decrease the number of stacked thylakoids per granum in seconds to minutes in leaves. It is proposed that these dynamic changes depend on reversible macro-reorganization of some light-harvesting complex IIb and photosystem II supracomplexes within the plant thylakoid network owing to differential phosphorylation cycles and other biochemical changes known to ensure flexibility in photosynthetic function in vivo. Some lingering grana enigmas remain: elucidation of the mechanisms involved in the dynamic architecture of the thylakoid membrane network under fluctuating irradiance and its implications for function merit extensive further studies.
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Affiliation(s)
- Jan M Anderson
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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20
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Belgio E, Johnson M, Jurić S, Ruban A. Higher plant photosystem II light-harvesting antenna, not the reaction center, determines the excited-state lifetime-both the maximum and the nonphotochemically quenched. Biophys J 2012; 102:2761-71. [PMID: 22735526 PMCID: PMC3379028 DOI: 10.1016/j.bpj.2012.05.004] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 05/02/2012] [Accepted: 05/07/2012] [Indexed: 11/28/2022] Open
Abstract
The maximum chlorophyll fluorescence lifetime in isolated photosystem II (PSII) light-harvesting complex (LHCII) antenna is 4 ns; however, it is quenched to 2 ns in intact thylakoid membranes when PSII reaction centers (RCIIs) are closed (Fm). It has been proposed that the closed state of RCIIs is responsible for the quenching. We investigated this proposal using a new, to our knowledge, model system in which the concentration of RCIIs was highly reduced within the thylakoid membrane. The system was developed in Arabidopsis thaliana plants under long-term treatment with lincomycin, a chloroplast protein synthesis inhibitor. The treatment led to 1), a decreased concentration of RCIIs to 10% of the control level and, interestingly, an increased antenna component; 2), an average reduction in the yield of photochemistry to 0.2; and 3), an increased nonphotochemical chlorophyll fluorescence quenching (NPQ). Despite these changes, the average fluorescence lifetimes measured in Fm and Fm' (with NPQ) states were nearly identical to those obtained from the control. A 77 K fluorescence spectrum analysis of treated PSII membranes showed the typical features of preaggregation of LHCII, indicating that the state of LHCII antenna in the dark-adapted photosynthetic membrane is sufficient to determine the 2 ns Fm lifetime. Therefore, we conclude that the closed RCs do not cause quenching of excitation in the PSII antenna, and play no role in the formation of NPQ.
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Affiliation(s)
- Erica Belgio
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Matthew P. Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Snježana Jurić
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Alexander V. Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
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21
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Dinç E, Ceppi MG, Tóth SZ, Bottka S, Schansker G. The chl a fluorescence intensity is remarkably insensitive to changes in the chlorophyll content of the leaf as long as the chl a/b ratio remains unaffected. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:770-9. [PMID: 22342617 DOI: 10.1016/j.bbabio.2012.02.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 12/23/2011] [Accepted: 02/02/2012] [Indexed: 10/14/2022]
Abstract
The effects of changes in the chlorophyll (chl) content on the kinetics of the OJIP fluorescence transient were studied using two different approaches. An extensive chl loss (up to 5-fold decrease) occurs in leaves suffering from either an Mg(2+) or SO(4)(2-) deficiency. The effects of these treatments on the chl a/b ratio, which is related to antenna size, were very limited. This observation was confirmed by the identical light intensity dependencies of the K, J and I-steps of the fluorescence rise for three of the four treatments and by the absence of changes in the F(685 nm)/F(695 nm)-ratio of fluorescence emission spectra measured at 77K. Under these conditions, the F(0) and F(M)-values were essentially insensitive to the chl content. A second experimental approach consisted of the treatment of wheat leaves with specifically designed antisense oligodeoxynucleotides that interfered with the translation of mRNA of the genes coding for chl a/b binding proteins. This way, leaves with a wide range of chl a/b ratios were created. Under these conditions, an inverse proportional relationship between the F(M) values and the chl a/b ratio was observed. A strong effect of the chl a/b ratio on the fluorescence intensity was also observed for barley Chlorina f2 plants that lack chl b. The data suggest that the chl a/b ratio (antenna size) is a more important determinant of the maximum fluorescence intensity than the chl content of the leaf.
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Affiliation(s)
- Emine Dinç
- Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, Hungary
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22
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Johnson MP, Zia A, Ruban AV. Elevated ΔpH restores rapidly reversible photoprotective energy dissipation in Arabidopsis chloroplasts deficient in lutein and xanthophyll cycle activity. PLANTA 2012; 235:193-204. [PMID: 21866345 DOI: 10.1007/s00425-011-1502-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 08/08/2011] [Indexed: 05/07/2023]
Abstract
The xanthophylls of the light-harvesting complexes of photosystem II (LHCII), zeaxanthin, and lutein are thought to be essential for non-photochemical quenching (NPQ). NPQ is a process of photoprotective energy dissipation in photosystem II (PSII). The major rapidly reversible component of NPQ, qE, is activated by the transmembrane proton gradient, and involves the quenching of antenna chlorophyll excited states by the xanthophylls lutein and zeaxanthin. Using diaminodurene (DAD), a mediator of cyclic electron flow around photosystem I, to enhance ΔpH we demonstrate that qE can still be formed in the absence of lutein and light-induced formation of zeaxanthin in chloroplasts derived from the normally qE-deficient lut2npq1 mutant of Arabidopsis. The qE induced by high ΔpH in lut2npq1 chloroplasts quenched the level of fluorescence when all PSII reaction centers were in the open state (F (o) state), protected PSII reaction centers from photoinhibition, was sensitive to the uncoupler nigericin, and was accompanied by absorption changes in the 410-565 nm region. Titrations show the ΔpH threshold for activation of qE in lut2npq1 chloroplasts lies outside the normal physiological range and is highly cooperative. Comparison of quenching in isolated trimeric (LHCII) and monomeric (CP26) light-harvesting complexes from lut2npq1 plants revealed a similarly shifted pH dependency compared with wild-type LHCII. The implications for the roles of lutein and zeaxanthin as direct quenchers of excitation energy are discussed. Furthermore, we argue that the control over the proton-antenna association constant, pK, occurs via influence of xanthophyll structure on the interconnected phenomena of light-harvesting antenna reorganization/aggregation and hydrophobicity.
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Affiliation(s)
- Matthew P Johnson
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, Fogg Building, London, E1 4NS, UK
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23
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Alboresi A, Gerotto C, Cazzaniga S, Bassi R, Morosinotto T. A red-shifted antenna protein associated with photosystem II in Physcomitrella patens. J Biol Chem 2011; 286:28978-28987. [PMID: 21705318 DOI: 10.1074/jbc.m111.226126] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antenna systems of plants and green algae are made up of pigment-protein complexes belonging to the light-harvesting complex (LHC) multigene family. LHCs increase the light-harvesting cross-section of photosystems I and II and catalyze photoprotective reactions that prevent light-induced damage in an oxygenic environment. The genome of the moss Physcomitrella patens contains two genes encoding LHCb9, a new antenna protein that bears an overall sequence similarity to photosystem II antenna proteins but carries a specific motif typical of photosystem I antenna proteins. This consists of the presence of an asparagine residue as a ligand for Chl 603 (A5) chromophore rather than a histidine, the common ligand in all other LHCbs. Asparagine as a Chl 603 (A5) ligand generates red-shifted spectral forms associated with photosystem I rather than with photosystem II, suggesting that in P. patens, the energy landscape of photosystem II might be different with respect to that of most green algae and plants. In this work, we show that the in vitro refolded LHCb9-pigment complexes carry a red-shifted fluorescence emission peak, different from all other known photosystem II antenna proteins. By using a specific antibody, we localized LHCb9 within PSII supercomplexes in the thylakoid membranes. This is the first report of red-shifted spectral forms in a PSII antenna system, suggesting that this biophysical feature might have a special role either in optimization of light use efficiency or in photoprotection in the specific environmental conditions experienced by this moss.
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Affiliation(s)
- Alessandro Alboresi
- Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134 Verona, Italy
| | - Caterina Gerotto
- Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58 B, 35121 Padova, Italy, and
| | - Stefano Cazzaniga
- Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134 Verona, Italy
| | - Roberto Bassi
- Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134 Verona, Italy,; ICG-3, Phytosphäre Forschungszentrum Jülich, 52425 Jülich, Germany.
| | - Tomas Morosinotto
- Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58 B, 35121 Padova, Italy, and
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24
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Zia A, Johnson MP, Ruban AV. Acclimation- and mutation-induced enhancement of PsbS levels affects the kinetics of non-photochemical quenching in Arabidopsis thaliana. PLANTA 2011; 233:1253-1264. [PMID: 21340700 DOI: 10.1007/s00425-011-1380-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 02/07/2011] [Indexed: 05/30/2023]
Abstract
The efficiency of photosystem II antenna complexes (LHCs) in higher plants must be regulated to avoid potentially damaging overexcitation of the reaction centre in excess light. Regulation is achieved via a feedback mechanism known as non-photochemical quenching (NPQ), triggered the proton gradient (ΔpH) causing heat dissipation within the LHC antenna. ΔpH causes protonation of the LHCs, the PsbS protein and triggers the enzymatic de-epoxidation of the xanthophyll, violaxanthin, to zeaxanthin. A key step in understanding the mechanism is to decipher whether PsbS and zeaxanthin cooperate to promote NPQ. To obtain clues about their respective functions we studied the effects of PsbS and zeaxanthin on the rates of NPQ formation and relaxation in wild-type Arabidopsis leaves and those overexpressing PsbS (L17) or lacking zeaxanthin (npq1). Overexpression of PsbS was found to increase the rate of NPQ formation, as previously reported for zeaxanthin. However, PsbS overexpression also increased the rate of NPQ relaxation, unlike zeaxanthin, which is known decrease the rate. The enhancement of PsbS levels in plants lacking zeaxanthin (npq1) by either acclimation to high light or crossing with L17 plants showed that the effect of PsbS was independent of zeaxanthin. PsbS levels also affected the kinetics of the 535 nm absorption change (ΔA535), which monitors the formation of the conformational state of the LHC antenna associated with NPQ, in an identical way. The antagonistic action of PsbS and zeaxanthin with respect to NPQ and ΔA535 relaxation kinetics suggests that the two molecules have distinct regulatory functions.
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Affiliation(s)
- Ahmad Zia
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End, Bancroft Road, Fogg Building, London E14NS, UK
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25
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Cui YL, Jia QS, Yin QQ, Lin GN, Kong MM, Yang ZN. The GDC1 gene encodes a novel ankyrin domain-containing protein that is essential for grana formation in Arabidopsis. PLANT PHYSIOLOGY 2011; 155:130-41. [PMID: 21098677 PMCID: PMC3075748 DOI: 10.1104/pp.110.165589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In land-plant chloroplasts, the grana play multiple roles in photosynthesis, including the potential increase of photosynthetic capacity in light and enhancement of photochemical efficiency in shade. However, the molecular mechanisms of grana formation remain elusive. Here, we report a novel gene, Grana-Deficient Chloroplast1 (GDC1), required for chloroplast grana formation in Arabidopsis (Arabidopsis thaliana). In the chloroplast of knockout mutant gdc1-3, only stromal thylakoids were observed, and they could not stack together to form appressed grana. The mutant exhibited seedling lethality with pale green cotyledons and true leaves. Further blue native-polyacrylamide gel electrophoresis analysis indicated that the trimeric forms of Light-Harvesting Complex II (LHCII) were scarcely detected in gdc1-3, confirming previous reports that the LHCII trimer is essential for grana formation. The Lhcb1 protein, the major component of the LHCIIb trimer, was substantially reduced, and another LHCIIb trimer component, Lhcb2, was slightly reduced in the gdc1-3 mutant, although their transcription levels were not altered in the mutant. This suggests that defective LHCII trimer formation in gdc1-3 is due to low amounts of Lhcb1 and Lhcb2. GDC1 encodes a chloroplast protein with an ankyrin domain within the carboxyl terminus. It was highly expressed in Arabidopsis green tissues, and its expression was induced by photosignaling pathways. Immunoblot analysis of the GDC1-green fluorescent protein (GFP) fusion protein in 35S::GDC1-GFP transgenic plants with GFP antibody indicates that GDC1 is associated with an approximately 440-kD thylakoid protein complex instead of the LHCII trimer. This shows that GDC1 may play an indirect role in LHCII trimerization during grana formation.
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26
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Effect of xanthophyll composition on the chlorophyll excited state lifetime in plant leaves and isolated LHCII. Chem Phys 2010. [DOI: 10.1016/j.chemphys.2009.12.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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27
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Damkjær JT, Kereïche S, Johnson MP, Kovacs L, Kiss AZ, Boekema EJ, Ruban AV, Horton P, Jansson S. The photosystem II light-harvesting protein Lhcb3 affects the macrostructure of photosystem II and the rate of state transitions in Arabidopsis. THE PLANT CELL 2009; 21:3245-56. [PMID: 19880802 PMCID: PMC2782274 DOI: 10.1105/tpc.108.064006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 09/17/2009] [Accepted: 10/06/2009] [Indexed: 05/18/2023]
Abstract
The main trimeric light-harvesting complex of higher plants (LHCII) consists of three different Lhcb proteins (Lhcb1-3). We show that Arabidopsis thaliana T-DNA knockout plants lacking Lhcb3 (koLhcb3) compensate for the lack of Lhcb3 by producing increased amounts of Lhcb1 and Lhcb2. As in wild-type plants, LHCII-photosystem II (PSII) supercomplexes were present in Lhcb3 knockout plants (koLhcb3), and preservation of the LHCII trimers (M trimers) indicates that the Lhcb3 in M trimers has been replaced by Lhcb1 and/or Lhcb2. However, the rotational position of the M LHCII trimer was altered, suggesting that the Lhcb3 subunit affects the macrostructural arrangement of the LHCII antenna. The absence of Lhcb3 did not result in any significant alteration in PSII efficiency or qE type of nonphotochemical quenching, but the rate of transition from State 1 to State 2 was increased in koLhcb3, although the final extent of state transition was unchanged. The level of phosphorylation of LHCII was increased in the koLhcb3 plants compared with wild-type plants in both State 1 and State 2. The relative increase in phosphorylation upon transition from State 1 to State 2 was also significantly higher in koLhcb3. It is suggested that the main function of Lhcb3 is to modulate the rate of state transitions.
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Affiliation(s)
- Jakob T. Damkjær
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90187 Umeå, Sweden
| | - Sami Kereïche
- Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Matthew P. Johnson
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom
| | - Laszlo Kovacs
- Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Anett Z. Kiss
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90187 Umeå, Sweden
| | - Egbert J. Boekema
- Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Alexander V. Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom
| | - Peter Horton
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom
| | - Stefan Jansson
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90187 Umeå, Sweden
- Address correspondence to
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Kim EH, Li XP, Razeghifard R, Anderson JM, Niyogi KK, Pogson BJ, Chow WS. The multiple roles of light-harvesting chlorophyll a/b-protein complexes define structure and optimize function of Arabidopsis chloroplasts: A study using two chlorophyll b-less mutants. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:973-84. [DOI: 10.1016/j.bbabio.2009.04.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 04/13/2009] [Accepted: 04/15/2009] [Indexed: 10/20/2022]
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Ruban AV, Johnson MP. Dynamics of higher plant photosystem cross-section associated with state transitions. PHOTOSYNTHESIS RESEARCH 2009; 99:173-83. [PMID: 19037743 DOI: 10.1007/s11120-008-9387-x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 11/05/2008] [Indexed: 05/03/2023]
Abstract
Photosynthetic state transitions are a well-known phenomenon of short-term adaptation of the photosynthetic membrane to changes in spectral quality of light in low light environments. The principles of the monitoring and quantification of the process in higher plants are revised here. The use of the low-temperature excitation fluorescence spectroscopy for analysis of the photosystem I antenna cross-section dynamics is described. This cross section was found to increase by 20-25% exclusively due to the migration and attachment of LHCIIb complex in State 2. Analysis of the fine structure of the additional PSI cross-section spectrum revealed the 510 nm band, characteristic of Lutein 2 of LHCIIb and present only when the complex is in a trimeric state. The excitation fluorescence spectrum of the phospho-LHCII resembles the spectrum of aggregated and hence quenched LHCII. This novel observation could explain the fact that at no point in the course of the state transition high fluorescence and long lifetime components of detached trimeric LHCII have ever been observed. In the plants lacking Lhcb1 and 2 proteins and unable to perform state transitions, compensatory sustained adjustments of the photosystem I and II antennae have been revealed. Whilst the major part of the photosystem II antenna is built largely of CP26 trimers, possessing less chlorophyll b and more of the red-shifted chlorophyll a, photosystem I in these plants contains more than 20% of extra LHCI antenna enriched in chlorophyll b. Hence, both photosystems in the plants lacking state transitions have less spectrally distinct antennae, which enable to avoid energy imbalance due to the changes in the light quality. These alterations reveal remarkable plasticity of the higher plant photosynthetic antenna design providing the basis for a flexible adaptation to the light environment.
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Affiliation(s)
- Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, Fogg Building, London, E1 4NS, UK.
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30
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Horton P, Johnson MP, Perez-Bueno ML, Kiss AZ, Ruban AV. Photosynthetic acclimation: Does the dynamic structure and macro-organisation of photosystem II in higher plant grana membranes regulate light harvesting states? FEBS J 2008; 275:1069-79. [DOI: 10.1111/j.1742-4658.2008.06263.x] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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31
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Kiss AZ, Ruban AV, Horton P. The PsbS protein controls the organization of the photosystem II antenna in higher plant thylakoid membranes. J Biol Chem 2007; 283:3972-8. [PMID: 18055452 DOI: 10.1074/jbc.m707410200] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PsbS subunit of photosystem II (PSII) plays a key role in nonphotochemical quenching (NPQ), the major photoprotective regulatory mechanism in higher plant thylakoid membranes, but its mechanism of action is unknown. Here we describe direct evidence that PsbS controls the organization of PSII and its light harvesting system (LHCII). The changes in chlorophyll fluorescence amplitude associated with the Mg(2+)-dependent restacking of thylakoid membranes were measured in thylakoids prepared from wild-type plants, a PsbS-deficient mutant and a PsbS overexpresser. The Mg(2+) requirement and sigmoidicity of the titration curves for the fluorescence rise were negatively correlated with the level of PsbS. Using a range of PsbS mutants, this effect of PsbS was shown not to depend upon its efficacy in controlling NPQ, but to be related only to protein concentration. Electron microscopy and fluorescence spectroscopy showed that this effect was because of enhancement of the Mg(2+)-dependent re-association of PSII and LHCII by PsbS, rather than an effect on stacking per se. In the presence of PsbS the LHCII.PSII complex was also more readily removed from thylakoid membranes by detergent, and the level of PsbS protein correlated with the amplitude of the psi-type CD signal originating from features of LHCII.PSII organization. It is proposed that PsbS regulates the interaction between LHCII and PSII in the grana membranes, explaining how it acts as a pH-dependent trigger of the conformational changes within the PSII light harvesting system that result in NPQ.
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Affiliation(s)
- Anett Z Kiss
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
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Johnson MP, Havaux M, Triantaphylidès C, Ksas B, Pascal AA, Robert B, Davison PA, Ruban AV, Horton P. Elevated zeaxanthin bound to oligomeric LHCII enhances the resistance of Arabidopsis to photooxidative stress by a lipid-protective, antioxidant mechanism. J Biol Chem 2007; 282:22605-18. [PMID: 17553786 DOI: 10.1074/jbc.m702831200] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The xanthophyll cycle has a major role in protecting plants from photooxidative stress, although the mechanism of its action is unclear. Here, we have investigated Arabidopsis plants overexpressing a gene encoding beta-carotene hydroxylase, containing nearly three times the amount of xanthophyll cycle carotenoids present in the wild-type. In high light at low temperature wild-type plants exhibited symptoms of severe oxidative stress: lipid peroxidation, chlorophyll bleaching, and photoinhibition. In transformed plants, which accumulate over twice as much zeaxanthin as the wild-type, these symptoms were significantly ameliorated. The capacity of non-photochemical quenching is not significantly different in transformed plants compared with wild-type and therefore an enhancement of this process cannot be the cause of the stress tolerant phenotype. Rather, it is concluded that it results from the antioxidant effect of zeaxanthin. 80-90% of violaxanthin and zeaxanthin in wild-type and transformed plants was localized to an oligomeric LHCII fraction prepared from thylakoid membranes. The binding of these pigments in intact membranes was confirmed by resonance Raman spectroscopy. Based on the structural model of LHCII, we suggest that the protein/lipid interface is the active site for the antioxidant activity of zeaxanthin, which mediates stress tolerance by the protection of bound lipids.
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Affiliation(s)
- Matthew P Johnson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, United Kingdom
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Umate P, Schwenkert S, Karbat I, Bosco CD, Mlcòchová L, Volz S, Zer H, Herrmann RG, Ohad I, Meurer J. Deletion of PsbM in tobacco alters the QB site properties and the electron flow within photosystem II. J Biol Chem 2007; 282:9758-9767. [PMID: 17261590 DOI: 10.1074/jbc.m608117200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Photosystem II, the oxygen-evolving complex of photosynthetic organisms, includes an intriguingly large number of low molecular weight polypeptides, including PsbM. Here we describe the first knock-out of psbM using a transplastomic, reverse genetics approach in a higher plant. Homoplastomic Delta psbM plants exhibit photoautotrophic growth. Biochemical, biophysical, and immunological analyses demonstrate that PsbM is not required for biogenesis of higher order photosystem II complexes. However, photosystem II is highly light-sensitive, and its activity is significantly decreased in Delta psbM, whereas kinetics of plastid protein synthesis, reassembly of photosystem II, and recovery of its activity are comparable with the wild type. Unlike wild type, phosphorylation of the reaction center proteins D1 and D2 is severely reduced, whereas the redox-controlled phosphorylation of photosystem II light-harvesting complex is reversely regulated in Delta psbM plants because of accumulation of reduced plastoquinone in the dark and a limited photosystem II-mediated electron transport in the light. Charge recombination in Delta psbM measured by thermoluminescence oscillations significantly differs from the 2/6 patterns in the wild type. A simulation program of thermoluminescence oscillations indicates a higher Q(B)/Q(-)(B) ratio in dark-adapted mutant thylakoids relative to the wild type. The interaction of the Q(A)/Q(B) sites estimated by shifts in the maximal thermoluminescence emission temperature of the Q band, induced by binding of different herbicides to the Q(B) site, is changed indicating alteration of the activation energy for back electron flow. We conclude that PsbM is primarily involved in the interaction of the redox components important for the electron flow within, outward, and backward to photosystem II.
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Affiliation(s)
- Pavan Umate
- Department of Biology I, Botany, Ludwig-Maximilians-University, Menzingerstrasse 67, 80638 Munich, Germany
| | - Serena Schwenkert
- Department of Biology I, Botany, Ludwig-Maximilians-University, Menzingerstrasse 67, 80638 Munich, Germany
| | - Izhar Karbat
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, 69978 Ramat-Aviv, Tel-Aviv, Israel
| | - Cristina Dal Bosco
- Department of Biology I, Botany, Ludwig-Maximilians-University, Menzingerstrasse 67, 80638 Munich, Germany
| | - Lada Mlcòchová
- Department of Biology I, Botany, Ludwig-Maximilians-University, Menzingerstrasse 67, 80638 Munich, Germany
| | - Stefanie Volz
- Department of Biology I, Botany, Ludwig-Maximilians-University, Menzingerstrasse 67, 80638 Munich, Germany
| | - Hagit Zer
- Minerva Avron, Even-Ari Center of Photosynthesis Research, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Reinhold G Herrmann
- Department of Biology I, Botany, Ludwig-Maximilians-University, Menzingerstrasse 67, 80638 Munich, Germany
| | - Itzhak Ohad
- Department of Biological Chemistry, Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Jörg Meurer
- Department of Biology I, Botany, Ludwig-Maximilians-University, Menzingerstrasse 67, 80638 Munich, Germany.
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Lucinski R, Schmid VHR, Jansson S, Klimmek F. Lhca5 interaction with plant photosystem I. FEBS Lett 2006; 580:6485-8. [PMID: 17107674 DOI: 10.1016/j.febslet.2006.10.063] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 10/30/2006] [Accepted: 10/30/2006] [Indexed: 11/22/2022]
Abstract
In the outer antenna (LHCI) of higher plant photosystem I (PSI) four abundantly expressed light-harvesting protein of photosystem I (Lhca)-type proteins are organized in two heterodimeric domains (Lhca1/Lhca4 and Lhca2/Lhca3). Our cross-linking studies on PSI-LHCI preparations from wildtype Arabidopsis and pea plants indicate an exclusive interaction of the rarely expressed Lhca5 light-harvesting protein with LHCI in the Lhca2/Lhca3-site. In PSI particles with an altered LHCI composition Lhca5 assembles in the Lhca1/Lhca4 site, partly as a homodimer. This flexibility indicates a binding-competitive model for the LHCI assembly in plants regulated by molecular interactions of the Lhca proteins with the PSI core.
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Affiliation(s)
- Robert Lucinski
- Adam Mickiewicz University, Department of Plant Physiology, Institute of Experimental Biology, Al. Niepodleglosci 14, 61-713, Poznan, Poland
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35
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Wehling A, Walla PJ. A two-photon excitation study on the role of carotenoid dark states in the regulation of plant photosynthesis. PHOTOSYNTHESIS RESEARCH 2006; 90:101-10. [PMID: 17211584 DOI: 10.1007/s11120-006-9088-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 07/17/2006] [Indexed: 05/13/2023]
Abstract
Plants are exposed to sun light intensities that vary rapidly over several orders of magnitude during a typical day. It is known that the regulation of photosynthetic activity under these circumstances is essential for the survival and fitness of natural and gene modified plants. A quick balancing between utilization and dissipation of absorbed light energy ensures optimized levels of CO(2) fixation and protection from photo damage by excessive light-irradiation. Despite intensive investigations the biophysical mechanisms of these regulation processes are still poorly understood. Potentially involved singlet states of carotenoids are optically "dark" and so far it was impossible to investigate their role directly in living plants by conventional absorption or fluorescence spectroscopy. Here, we show by selective two-photon excitation of the carotenoid dark states in plant that a dominant part of the regulation is correlated with a substantial change in the energy transfer between these states and the chlorophylls (Chl). The results support a considerable role of the molecular gear shift model in which a reversible and step-wise enzymatic modification of the electronic structure of xanthophyll carotenoids enables a switching between carotenoid-to-Chl light-harvesting and Chl-to-carotenoid quenching. The shifting can be observed in real time in any plant. Treatment with the xanthophyll cycle inhibitor dithiothreitol slowed down both the light adaptation and the carotenoid-Chl energy flow changes to the same extent. Based on these results, we propose a biophysical quenching model in which both carotenoid dark states and radical cations contribute to the dissipation of excessive excitation energy.
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Affiliation(s)
- Axel Wehling
- Department for Biophysical Chemistry, Institute for Physical and Theoretical Chemistry, Technical University of Brunswick, Hans-Sommerstr. 10, 38106, Braunschweig, Germany
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