1
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Meredith SA, Kusunoki Y, Evans SD, Morigaki K, Connell SD, Adams PG. Evidence for a transfer-to-trap mechanism of fluorophore concentration quenching in lipid bilayers. Biophys J 2024; 123:3242-3256. [PMID: 39039794 PMCID: PMC11427787 DOI: 10.1016/j.bpj.2024.07.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 05/30/2024] [Accepted: 07/19/2024] [Indexed: 07/24/2024] Open
Abstract
It is important to understand the behaviors of fluorescent molecules because, firstly, they are often utilized as probes in biophysical experiments and, secondly, they are crucial cofactors in biological processes such as photosynthesis. A phenomenon called "fluorescence quenching" occurs when fluorophores are present at high concentrations, but the mechanisms for quenching are debated. Here, we used a technique called "in-membrane electrophoresis" to generate concentration gradients of fluorophores within a supported lipid bilayer, across which quenching was expected to occur. Fluorescence lifetime imaging microscopy (FLIM) provides images where the fluorescence intensity in each pixel is correlated to fluorescence lifetime: the intensity provides information about the location and concentration of fluorophores and the lifetime reveals the occurrence of energy-dissipative processes. FLIM was used to compare the quenching behavior of three commonly used fluorophores: Texas Red (TR), nitrobenzoaxadiazole (NBD), and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY). FLIM images provided evidence of quenching in regions where the fluorophores accumulated, but the degree of quenching varied between the different fluorophores. The relationship between quenching and concentration was quantified and the "critical radius for trap formation," representing the relative quenching strength, was calculated as 2.70, 2.02, and 1.14 nm, for BODIPY, TR, and NBD, respectively. The experimental data support the theory that quenching takes place via a "transfer-to-trap" mechanism which proposes, firstly, that excitation energy is transferred between fluorophores and may reach a "trap site," resulting in immediate energy dissipation, and, secondly, that trap sites are formed in a concentration-dependent manner. Some previous work suggested that quenching occurs only when fluorophores aggregate, or form long-lived dimers, but our data and this theory argue that traps may be "statistical pairs" of fluorophores that exist only transiently. Our findings should inspire future work to assess whether these traps can be charge-transfer states, excited-state dimers, or something else.
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Affiliation(s)
- Sophie A Meredith
- School of Physics and Astronomy, University of Leeds, Leeds, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Yuka Kusunoki
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Kobe, Japan
| | - Stephen D Evans
- School of Physics and Astronomy, University of Leeds, Leeds, UK
| | - Kenichi Morigaki
- Graduate School of Agricultural Science and Biosignal Research Center, Kobe University, Kobe, Japan
| | - Simon D Connell
- School of Physics and Astronomy, University of Leeds, Leeds, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.
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2
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Pedraza-González L, Accomasso D, Cupellini L, Granucci G, Mennucci B. Ultrafast excited-state dynamics of Luteins in the major light-harvesting complex LHCII. Photochem Photobiol Sci 2024; 23:303-314. [PMID: 38151602 DOI: 10.1007/s43630-023-00518-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/23/2023] [Indexed: 12/29/2023]
Abstract
Carotenoid pigments are known to present a functional versatility when bound to light-harvesting complexes. This versatility originates from a strong correlation between a complex electronic structure and a flexible geometry that is easily tunable by the surrounding protein environment. Here, we investigated how the different L1 and L2 sites of the major trimeric light-harvesting complex (LHCII) of green plants tune the electronic structure of the two embedded luteins, and how this reflects on their ultrafast dynamics upon excitation. By combining molecular dynamics and quantum mechanics/molecular mechanics calculations, we found that the two luteins feature a different conformation around the second dihedral angle in the lumenal side. The s-cis preference of the lutein in site L2 allows for a more planar geometry of the π -conjugated backbone, which results in an increased degree of delocalization and a reduced excitation energy, explaining the experimentally observed red shift. Despite these remarkable differences, according to surface hopping simulations the two luteins present analogous ultrafast dynamics upon excitation: the bright S 2 state quickly decays (in ∼ 50 fs) to the dark intermediate S x , eventually ending up in the S 1 state. Furthermore, by employing two different theoretical approaches (i.e., Förster theory and an excitonic version of surface hopping), we investigated the experimentally debated energy transfer between the two luteins. With both approaches, no evident energy transfer was observed in the ultrafast timescale.
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Affiliation(s)
- Laura Pedraza-González
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
| | - Davide Accomasso
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
| | - Lorenzo Cupellini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
| | - Giovanni Granucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy.
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3
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Gray C, Kailas L, Adams PG, Duffy CDP. Unravelling the fluorescence kinetics of light-harvesting proteins with simulated measurements. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2024; 1865:149004. [PMID: 37699505 DOI: 10.1016/j.bbabio.2023.149004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 08/24/2023] [Accepted: 08/31/2023] [Indexed: 09/14/2023]
Abstract
The plant light-harvesting pigment-protein complex LHCII is the major antenna sub-unit of PSII and is generally (though not universally) accepted to play a role in photoprotective energy dissipation under high light conditions, a process known Non-Photochemical Quenching (NPQ). The underlying mechanisms of energy trapping and dissipation within LHCII are still debated. Various models have been proposed for the underlying molecular detail of NPQ, but they are often based on different interpretations of very similar transient absorption measurements of isolated complexes. Here we present a simulated measurement of the fluorescence decay kinetics of quenched LHCII aggregates to determine whether this relatively simple measurement can discriminate between different potential NPQ mechanisms. We simulate not just the underlying physics (excitation, energy migration, quenching and singlet-singlet annihilation) but also the signal detection and typical experimental data analysis. Comparing this to a selection of published fluorescence decay kinetics we find that: (1) Different proposed quenching mechanisms produce noticeably different fluorescence kinetics even at low (annihilation free) excitation density, though the degree of difference is dependent on pulse width. (2) Measured decay kinetics are consistent with most LHCII trimers becoming relatively slow excitation quenchers. A small sub-population of very fast quenchers produces kinetics which do not resemble any observed measurement. (3) It is necessary to consider at least two distinct quenching mechanisms in order to accurately reproduce experimental kinetics, supporting the idea that NPQ is not a simple binary switch.
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Affiliation(s)
- Callum Gray
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End, London E1 4NS, United Kingdom
| | - Lekshmi Kailas
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Christopher D P Duffy
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End, London E1 4NS, United Kingdom.
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4
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Navakoudis E, Stergiannakos T, Daskalakis V. A perspective on the major light-harvesting complex dynamics under the effect of pH, salts, and the photoprotective PsbS protein. PHOTOSYNTHESIS RESEARCH 2023; 156:163-177. [PMID: 35816266 PMCID: PMC10070230 DOI: 10.1007/s11120-022-00935-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
The photosynthetic apparatus is a highly modular assembly of large pigment-binding proteins. Complexes called antennae can capture the sunlight and direct it from the periphery of two Photosystems (I, II) to the core reaction centers, where it is converted into chemical energy. The apparatus must cope with the natural light fluctuations that can become detrimental to the viability of the photosynthetic organism. Here we present an atomic scale view of the photoprotective mechanism that is activated on this line of defense by several photosynthetic organisms to avoid overexcitation upon excess illumination. We provide a complete macroscopic to microscopic picture with specific details on the conformations of the major antenna of Photosystem II that could be associated with the switch from the light-harvesting to the photoprotective state. This is achieved by combining insight from both experiments and all-atom simulations from our group and the literature in a perspective article.
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Affiliation(s)
- Eleni Navakoudis
- Department of Chemical Engineering, Cyprus University of Technology, 95 Eirinis Street, 3603, Limassol, Cyprus
| | - Taxiarchis Stergiannakos
- Department of Chemical Engineering, Cyprus University of Technology, 95 Eirinis Street, 3603, Limassol, Cyprus
| | - Vangelis Daskalakis
- Department of Chemical Engineering, Cyprus University of Technology, 95 Eirinis Street, 3603, Limassol, Cyprus.
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5
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Zhao H, Xu X, Wang S, Li S, Sun C, Men Z. Modulated excited state geometry and Electron-Phonon coupling of lutein by temperature and solvent polarizability. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 280:121520. [PMID: 35728401 DOI: 10.1016/j.saa.2022.121520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 06/07/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Resonance Raman spectroscopy is one of the spectroscopic methods often chosen for studying linear polyene molecules because the Raman intensities of their υ1 (C = C) and υ2 (C-C) stretching vibrations are sensitive to electron-phonon coupling and the π-electron energy gap. Here, the resonance Raman and absorption spectra of lutein were studied as a function of solvent polarizabilities and of temperature in the CS2 solvent. For lutein in CS2, as the temperature decreased and CS solidified, the Raman scattering cross-section (RSCS) and the electron-phonon coupling constant had opposite dependence trends on temperature. The wavenumber of the lutein 0-0 electronic transition showed a marked shift to lower wavenumbers when the polarizability of the solvents decreased, and the Huang-Rhys (HR) factors and electron-phonon coupling also decreased. This work helps explore the influence of the external environment (e.g., temperature and solvent) on the excited state geometry of linear polyene molecules.
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Affiliation(s)
- Haiying Zhao
- Key Laboratory of Physics and Technology for Advanced Batteries, College of Physics, Jilin University, Changchun 130012, China
| | - Xin Xu
- Key Laboratory of Physics and Technology for Advanced Batteries, College of Physics, Jilin University, Changchun 130012, China
| | - Shenghan Wang
- College of Physics, Jilin University, Changchun 130012, China
| | - Shuo Li
- College of Physics, Jilin University, Changchun 130012, China
| | - Chenglin Sun
- College of Physics, Jilin University, Changchun 130012, China.
| | - Zhiwei Men
- Key Laboratory of Physics and Technology for Advanced Batteries, College of Physics, Jilin University, Changchun 130012, China.
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6
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Kim E, Kubota-Kawai H, Kawai F, Yokono M, Minagawa J. Conformation of Light-Harvesting Complex II Trimer Depends upon Its Binding Site. J Phys Chem B 2022; 126:5855-5865. [PMID: 35920883 DOI: 10.1021/acs.jpcb.2c04061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The light-harvesting complex II (LHCII) trimer in plants functions as a major antenna complex and a quencher to protect it from photooxidative damage. Theoretical studies on the structure of an LHCII trimer have demonstrated that excitation energy transfer between chlorophylls (Chls) in LHCII can be modulated by its exquisite conformational fluctuation. However, conformational changes depending on its binding location have not yet been investigated, even though reorganization of protein complexes occurs by physiological regulations. In this study, we investigated conformational differences in LHCII by comparing published structures of an identical LHCII trimer in the three different photosystem supercomplexes from the green alga Chlamydomonas reinhardtii. Our results revealed distinct differences in Chl configurations as well as polypeptide conformations of the LHCII trimers depending on its binding location. We propose that these configurational differences readily modulate the function of LHCII and possibly lead to a change in excitation-energy flow over the photosynthetic supercomplex.
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Affiliation(s)
- Eunchul Kim
- Division of Environmental Photobiology, National Institute for Basic Biology, Okazaki 444-8585, Japan.,Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | | | - Fumihiro Kawai
- Faculty of Science, Yamagata University, Yamagata 990-8560, Japan
| | - Makio Yokono
- Division of Environmental Photobiology, National Institute for Basic Biology, Okazaki 444-8585, Japan.,Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Jun Minagawa
- Division of Environmental Photobiology, National Institute for Basic Biology, Okazaki 444-8585, Japan.,Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan
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7
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Mikalčiūtė A, Gelzinis A, Mačernis M, Büchel C, Robert B, Valkunas L, Chmeliov J. Structure-based model of fucoxanthin-chlorophyll protein complex: Calculations of chlorophyll electronic couplings. J Chem Phys 2022; 156:234101. [PMID: 35732526 DOI: 10.1063/5.0092154] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Diatoms are a group of marine algae that are responsible for a significant part of global oxygen production. Adapted to life in an aqueous environment dominated by the blue-green light, their major light-harvesting antennae-fucoxanthin-chlorophyll protein complexes (FCPs)-exhibit different pigment compositions than of plants. Despite extensive experimental studies, until recently the theoretical description of excitation energy dynamics in these complexes was limited by the lack of high-resolution structural data. In this work, we use the recently resolved crystallographic information of the FCP complex from Phaeodactylum tricornutum diatom [Wang et al., Science 363, 6427 (2019)] and quantum chemistry-based calculations to evaluate the chlorophyll transition dipole moments, atomic transition charges from electrostatic potential, and the inter-chlorophyll couplings in this complex. The obtained structure-based excitonic couplings form the foundation for any modeling of stationary or time-resolved spectroscopic data. We also calculate the inter-pigment Förster energy transfer rates and identify two quickly equilibrating chlorophyll clusters.
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Affiliation(s)
- Austėja Mikalčiūtė
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania
| | - Andrius Gelzinis
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania
| | - Mindaugas Mačernis
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania
| | - Claudia Büchel
- Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt, Germany
| | - Bruno Robert
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Leonas Valkunas
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania
| | - Jevgenij Chmeliov
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania
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8
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Ruban A, Saccon F. Chlorophyll a De-Excitation Pathways in the LHCII antenna. J Chem Phys 2022; 156:070902. [DOI: 10.1063/5.0073825] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alexander Ruban
- SBBS, Queen Mary University of London - Mile End Campus, United Kingdom
| | - Francesco Saccon
- School of Biological and Chemical Sciences, Queen Mary University of London - Mile End Campus, United Kingdom
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9
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Jakučionis M, Gaižiu Nas I, Šulskus J, Abramavičius D. Simulation of Ab Initio Optical Absorption Spectrum of β-Carotene with Fully Resolved S0 and S2 Vibrational Normal Modes. J Phys Chem A 2022; 126:180-189. [PMID: 34985272 DOI: 10.1021/acs.jpca.1c06115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic absorption spectrum of β-carotene (β-Car) is studied using quantum chemistry and quantum dynamics simulations. Vibrational normal modes were computed in optimized geometries of the electronic ground state S0 and the optically bright excited S2 state using the time-dependent density functional theory. By expressing the S2-state normal modes in terms of the ground-state modes, we find that no one-to-one correspondence between the ground- and excited-state vibrational modes exists. Using the ab initio results, we simulated the β-Car absorption spectrum with all 282 vibrational modes in a model solvent at 300 K using the time-dependent Dirac-Frenkel variational principle and are able to qualitatively reproduce the full absorption line shape. By comparing the 282-mode model with the prominent 2-mode model, widely used to interpret carotenoid experiments, we find that the full 282-mode model better describes the high-frequency progression of carotenoid absorption spectra; hence, vibrational modes become highly mixed during the S0 → S2 optical excitation. The obtained results suggest that electronic energy dissipation is mediated by numerous vibrational modes.
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Affiliation(s)
- Mantas Jakučionis
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
| | - Ignas Gaižiu Nas
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
| | - Juozas Šulskus
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
| | - Darius Abramavičius
- Institute of Chemical Physics, Vilnius University, Sauletekio Avenue 9-III, LT-10222 Vilnius, Lithuania
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10
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A different perspective for nonphotochemical quenching in plant antenna complexes. Nat Commun 2021; 12:7152. [PMID: 34887401 PMCID: PMC8660843 DOI: 10.1038/s41467-021-27526-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 11/19/2021] [Indexed: 11/23/2022] Open
Abstract
Light-harvesting complexes of plants exert a dual function of light-harvesting (LH) and photoprotection through processes collectively called nonphotochemical quenching (NPQ). While LH processes are relatively well characterized, those involved in NPQ are less understood. Here, we characterize the quenching mechanisms of CP29, a minor LHC of plants, through the integration of two complementary enhanced-sampling techniques, dimensionality reduction schemes, electronic calculations and the analysis of cryo-EM data in the light of the predicted conformational ensemble. Our study reveals that the switch between LH and quenching state is more complex than previously thought. Several conformations of the lumenal side of the protein occur and differently affect the pigments' relative geometries and interactions. Moreover, we show that a quenching mechanism localized on a single chlorophyll-carotenoid pair is not sufficient but many chlorophylls are simultaneously involved. In such a diffuse mechanism, short-range interactions between each carotenoid and different chlorophylls combined with a protein-mediated tuning of the carotenoid excitation energies have to be considered in addition to the commonly suggested Coulomb interactions.
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11
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Chrysafoudi A, Maity S, Kleinekathöfer U, Daskalakis V. Robust Strategy for Photoprotection in the Light-Harvesting Antenna of Diatoms: A Molecular Dynamics Study. J Phys Chem Lett 2021; 12:9626-9633. [PMID: 34585934 DOI: 10.1021/acs.jpclett.1c02498] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Diatoms generate a large portion of the oxygen produced on earth due to their exceptional light-harvesting properties involving fucoxanthin and chlorophyll-binding proteins (FCP). At the same time, an efficient adaptation of these complexes to fluctuating light conditions is necessary to protect the diatoms against photodamage. So far, structural and dynamic data for the interaction between FCP and the photoprotective LHCX family of proteins in diatoms are lacking. In this computational study, we provide a structural basis for a remarkable pH-dependent adaptation at the molecular level. Upon binding of the LHCX1 protein to the FCP complex together with a change in pH, conformational changes within the FCP protein result in a variation of the electronic coupling in a specific chlorophyll-fucoxanthin pair, leading to a change in the exciton transfer rate by almost an order of magnitude. A common strategy for photoprotection between diatoms and higher plants is identified and discussed.
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Affiliation(s)
- Anthi Chrysafoudi
- Department of Biology, University of Crete, Voutes University Campus, GR-70013 Heraklion, Crete, Greece
| | - Sayan Maity
- Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Ulrich Kleinekathöfer
- Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Vangelis Daskalakis
- Department of Chemical Engineering, Cyprus University of Technology, 30 Archbishop Kyprianou Str., 3603 Limassol, Cyprus
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12
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Investigating carotenoid photophysics in photosynthesis with 2D electronic spectroscopy. TRENDS IN CHEMISTRY 2021. [DOI: 10.1016/j.trechm.2021.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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13
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Agostini A, Nicol L, Da Roit N, Bortolus M, Croce R, Carbonera D. Altering the exciton landscape by removal of specific chlorophylls in monomeric LHCII provides information on the sites of triplet formation and quenching by means of ODMR and EPR spectroscopies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148481. [PMID: 34363791 DOI: 10.1016/j.bbabio.2021.148481] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/09/2021] [Accepted: 08/02/2021] [Indexed: 11/16/2022]
Abstract
The triplet states populated under illumination in the monomeric light-harvesting complex II (LHCII) were analyzed by EPR and Optically Detected Magnetic Resonance (ODMR) in order to fully characterize the perturbations introduced by site-directed mutations leading to the removal of key chlorophylls. We considered the A2 and A5 mutants, lacking Chls a612(a611) and Chl a603 respectively, since these Chls have been proposed as the sites of formation of triplet states which are subsequently quenched by the luteins. Chls a612 and Chl a603 belong to the two clusters determining the low energy exciton states in the complex. Their removal is expected to significantly alter the excitation energy transfer pathways. On the basis of the TR- and pulse EPR triplet spectra, the two symmetrically related pairs constituted by Chl a612/Lut620 and Chl a603/Lut621 were both possible candidate for triplet-triplet energy transfer (TTET). However, the ODMR results clearly show that only Lut620 is involved in triplet quenching. In the A5 mutant, the Chl a612/Lut620 pair retains this pivotal photoprotective role, while the A2 mutant was found to activate an alternative pathway involving the Chl a603/Lut621pair. These results shows that LHCII is characterized by a robust photoprotective mechanism, able to adapt to the removal of individual chromophores while maintaining a remarkable degree of Chl triplet quenching. Small amounts of unquenched Chl triplet states were also detected. The analysis of the results allowed us to assign the sites of "unquenched" chlorophyll triplets to Chl a610 and Chl a602.
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Affiliation(s)
- Alessandro Agostini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Lauren Nicol
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam and LaserLaB Amsterdam, Amsterdam, the Netherlands
| | - Nicola Da Roit
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Roberta Croce
- Biophysics of Photosynthesis, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam and LaserLaB Amsterdam, Amsterdam, the Netherlands
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.
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14
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Maity S, Daskalakis V, Elstner M, Kleinekathöfer U. Multiscale QM/MM molecular dynamics simulations of the trimeric major light-harvesting complex II. Phys Chem Chem Phys 2021; 23:7407-7417. [PMID: 33876100 DOI: 10.1039/d1cp01011e] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Photosynthetic processes are driven by sunlight. Too little of it and the photosynthetic machinery cannot produce the reductive power to drive the anabolic pathways. Too much sunlight and the machinery can get damaged. In higher plants, the major Light-Harvesting Complex (LHCII) efficiently absorbs the light energy, but can also dissipate it when in excess (quenching). In order to study the dynamics related to the quenching process but also the exciton dynamics in general, one needs to accurately determine the so-called spectral density which describes the coupling between the relevant pigment modes and the environmental degrees of freedom. To this end, Born-Oppenheimer molecular dynamics simulations in a quantum mechanics/molecular mechanics (QM/MM) fashion utilizing the density functional based tight binding (DFTB) method have been performed for the ground state dynamics. Subsequently, the time-dependent extension of the long-range-corrected DFTB scheme has been employed for the excited state calculations of the individual chlorophyll-a molecules in the LHCII complex. The analysis of this data resulted in spectral densities showing an astonishing agreement with the experimental counterpart in this rather large system. This consistency with an experimental observable also supports the accuracy, robustness, and reliability of the present multi-scale scheme. To the best of our knowledge, this is the first theoretical attempt on this large complex system is ever made to accurately simulate the spectral density. In addition, the resulting spectral densities and site energies were used to determine the exciton transfer rate within a special pigment pair consisting of a chlorophyll-a and a carotenoid molecule which is assumed to play a role in the balance between the light harvesting and quenching modes.
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Affiliation(s)
- Sayan Maity
- Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
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15
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Li F, Liu C, Streckaite S, Yang C, Xu P, Llansola-Portoles MJ, Ilioaia C, Pascal AA, Croce R, Robert B. A new, unquenched intermediate of LHCII. J Biol Chem 2021; 296:100322. [PMID: 33493515 PMCID: PMC7949128 DOI: 10.1016/j.jbc.2021.100322] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 11/23/2022] Open
Abstract
When plants are exposed to high-light conditions, the potentially harmful excess energy is dissipated as heat, a process called non-photochemical quenching. Efficient energy dissipation can also be induced in the major light-harvesting complex of photosystem II (LHCII) in vitro, by altering the structure and interactions of several bound cofactors. In both cases, the extent of quenching has been correlated with conformational changes (twisting) affecting two bound carotenoids, neoxanthin, and one of the two luteins (in site L1). This lutein is directly involved in the quenching process, whereas neoxanthin senses the overall change in state without playing a direct role in energy dissipation. Here we describe the isolation of an intermediate state of LHCII, using the detergent n-dodecyl-α-D-maltoside, which exhibits the twisting of neoxanthin (along with changes in chlorophyll–protein interactions), in the absence of the L1 change or corresponding quenching. We demonstrate that neoxanthin is actually a reporter of the LHCII environment—probably reflecting a large-scale conformational change in the protein—whereas the appearance of excitation energy quenching is concomitant with the configuration change of the L1 carotenoid only, reflecting changes on a smaller scale. This unquenched LHCII intermediate, described here for the first time, provides for a deeper understanding of the molecular mechanism of quenching.
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Affiliation(s)
- Fei Li
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Cheng Liu
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Simona Streckaite
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Chunhong Yang
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Pengqi Xu
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Manuel J Llansola-Portoles
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Cristian Ilioaia
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France.
| | - Andrew A Pascal
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Roberta Croce
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Bruno Robert
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France.
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16
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Gelzinis A, Augulis R, Büchel C, Robert B, Valkunas L. Confronting FCP structure with ultrafast spectroscopy data: evidence for structural variations. Phys Chem Chem Phys 2021; 23:806-821. [PMID: 33427836 DOI: 10.1039/d0cp05578f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diatoms are a major group of algae, responsible for a quarter of the global primary production on our planet. Their adaptation to marine environments is ensured by their light-harvesting antenna - the fucoxanthin-chlorophyll protein (FCP) complex, which absorbs strongly in the blue-green spectral region. Although these essential proteins have been the subject of many studies, for a long time their comprehensive description was not possible in the absence of structural data. Last year, the 3D structures of several FCP complexes were revealed. The structure of an FCP dimer was resolved by crystallography for the pennate diatom Phaeodactylum tricornutum [W. Wang et al., Science, 2019, 363, 6427] and the structure of the PSII supercomplex from the centric diatom Chaetoceros gracilis, containing several FCPs, was obtained by electron microscopy [X. Pi et al., Science, 2019, 365, 6452; R. Nagao et al., Nat. Plants, 2019, 5, 890]. In this Perspective article, we evaluate how precisely these structures may account for previously published ultrafast spectroscopy results, describing the excitation energy transfer in the FCP from another centric diatom Cyclotella meneghiniana. Surprisingly, we find that the published FCP structures cannot explain several observations obtained from ultrafast spectroscopy. Using the available structures, and results from electron microscopy, we construct a trimer-based FCP model for Cyclotella meneghiniana, consistent with ultrafast experimental data. As a whole, our observations suggest that the structures from the proteins belonging to the FCP family display larger variations than the equivalent LHC proteins in plants, which may reflect species-specific adaptations or original strategies for adapting to rapidly changing marine environments.
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Affiliation(s)
- Andrius Gelzinis
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius, Lithuania. and Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Sauletekio 3, 10257 Vilnius, Lithuania
| | - Ramūnas Augulis
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Sauletekio 3, 10257 Vilnius, Lithuania
| | - Claudia Büchel
- Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Straβe 9, 60438 Frankfurt, Germany
| | - Bruno Robert
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - Leonas Valkunas
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius, Lithuania. and Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Sauletekio 3, 10257 Vilnius, Lithuania
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17
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Gray C, Wei T, Polívka T, Daskalakis V, Duffy CDP. Trivial Excitation Energy Transfer to Carotenoids Is an Unlikely Mechanism for Non-photochemical Quenching in LHCII. FRONTIERS IN PLANT SCIENCE 2021; 12:797373. [PMID: 35095968 PMCID: PMC8792765 DOI: 10.3389/fpls.2021.797373] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/20/2021] [Indexed: 05/04/2023]
Abstract
Higher plants defend themselves from bursts of intense light via the mechanism of Non-Photochemical Quenching (NPQ). It involves the Photosystem II (PSII) antenna protein (LHCII) adopting a conformation that favors excitation quenching. In recent years several structural models have suggested that quenching proceeds via energy transfer to the optically forbidden and short-lived S 1 states of a carotenoid. It was proposed that this pathway was controlled by subtle changes in the relative orientation of a small number of pigments. However, quantum chemical calculations of S 1 properties are not trivial and therefore its energy, oscillator strength and lifetime are treated as rather loose parameters. Moreover, the models were based either on a single LHCII crystal structure or Molecular Dynamics (MD) trajectories about a single minimum. Here we try and address these limitations by parameterizing the vibronic structure and relaxation dynamics of lutein in terms of observable quantities, namely its linear absorption (LA), transient absorption (TA) and two-photon excitation (TPE) spectra. We also analyze a number of minima taken from an exhaustive meta-dynamical search of the LHCII free energy surface. We show that trivial, Coulomb-mediated energy transfer to S 1 is an unlikely quenching mechanism, with pigment movements insufficiently pronounced to switch the system between quenched and unquenched states. Modulation of S 1 energy level as a quenching switch is similarly unlikely. Moreover, the quenching predicted by previous models is possibly an artifact of quantum chemical over-estimation of S 1 oscillator strength and the real mechanism likely involves short-range interaction and/or non-trivial inter-molecular states.
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Affiliation(s)
- Callum Gray
- Digital Environment Research Institute (DERI), Queen Mary University of London, London, United Kingdom
| | - Tiejun Wei
- Digital Environment Research Institute (DERI), Queen Mary University of London, London, United Kingdom
| | - Tomáš Polívka
- Department of Physics, Faculty of Science, University of South Bohemia, Ceske Budejovice, Czechia
| | - Vangelis Daskalakis
- Department of Chemical Engineering, Cyprus University of Technology, Limassol, Cyprus
| | - Christopher D. P. Duffy
- Digital Environment Research Institute (DERI), Queen Mary University of London, London, United Kingdom
- *Correspondence: Christopher D. P. Duffy
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18
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Lapillo M, Cignoni E, Cupellini L, Mennucci B. The energy transfer model of nonphotochemical quenching: Lessons from the minor CP29 antenna complex of plants. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148282. [DOI: 10.1016/j.bbabio.2020.148282] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 12/13/2022]
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19
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Saccon F, Durchan M, Polívka T, Ruban AV. The robustness of the terminal emitter site in major LHCII complexes controls xanthophyll function during photoprotection. Photochem Photobiol Sci 2020; 19:1308-1318. [PMID: 32815966 DOI: 10.1039/d0pp00174k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Xanthophylls in light harvesting complexes perform a number of functions ranging from structural support to light-harvesting and photoprotection. In the major light harvesting complex of photosystem II in plants (LHCII), the innermost xanthophyll binding pockets are occupied by lutein molecules. The conservation of these sites within the LHC protein family suggests their importance in LHCII functionality. In the present work, we induced the photoprotective switch in LHCII isolated from the Arabidopsis mutant npq1lut2, where the lutein molecules are exchanged with violaxanthin. Despite the differences in the energetics of the pigments and the impairment of chlorophyll fluorescence quenching in vivo, we show that isolated complexes containing violaxanthin are still able to induce the quenching switch to a similar extent to wild type LHCII monomers. Moreover, the same spectroscopic changes take place, which suggest the involvement of the terminal emitter site (L1) in energy dissipation in both complexes. These results indicate the robust nature of the L1 xanthophyll binding domain in LHCII, where protein structural cues are the major determinant of the function of the bound carotenoid.
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Affiliation(s)
- Francesco Saccon
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road E1 4NS, London, UK.
| | - Milan Durchan
- University of South Bohemia, Institute of Physics, Faculty of Science, České Budějovice, Czech Republic
| | - Tomáš Polívka
- University of South Bohemia, Institute of Physics, Faculty of Science, České Budějovice, Czech Republic
| | - Alexander V Ruban
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road E1 4NS, London, UK.
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20
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Saccon F, Durchan M, Bína D, Duffy CD, Ruban AV, Polívka T. A Protein Environment-Modulated Energy Dissipation Channel in LHCII Antenna Complex. iScience 2020; 23:101430. [PMID: 32818906 PMCID: PMC7452274 DOI: 10.1016/j.isci.2020.101430] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/19/2020] [Accepted: 07/31/2020] [Indexed: 12/14/2022] Open
Abstract
The major light-harvesting complex of photosystem II (LHCII) is the main contributor to sunlight energy harvesting in plants. The flexible design of LHCII underlies a photoprotective mechanism whereby this complex switches to a dissipative state in response to high light stress, allowing the rapid dissipation of excess excitation energy (non-photochemical quenching, NPQ). In this work, we locked single LHCII trimers in a quenched conformation after immobilization of the complexes in polyacrylamide gels to impede protein interactions. A comparison of their pigment excited-state dynamics with quenched LHCII aggregates in buffer revealed the presence of a new spectral band at 515 nm arising after chlorophyll excitation. This is suggested to be the signature of a carotenoid excited state, linked to the quenching of chlorophyll singlet excited states. Our data highlight the marked sensitivity of pigment excited-state dynamics in LHCII to structural changes induced by the environment.
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Affiliation(s)
- Francesco Saccon
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road, E1 4NS London, UK
| | - Milan Durchan
- University of South Bohemia, Institute of Physics, Faculty of Science, České Budějovice, Czech Republic
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, České Budějovice, Czech Republic
| | - David Bína
- University of South Bohemia, Institute of Chemistry, Faculty of Science, České Budějovice, Czech Republic
- Czech Academy of Sciences, Biology Centre, Institute of Plant Molecular Biology, České Budějovice, Czech Republic
| | - Christopher D.P. Duffy
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road, E1 4NS London, UK
| | - Alexander V. Ruban
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road, E1 4NS London, UK
| | - Tomáš Polívka
- University of South Bohemia, Institute of Physics, Faculty of Science, České Budějovice, Czech Republic
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21
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Artes Vivancos JM, van Stokkum IHM, Saccon F, Hontani Y, Kloz M, Ruban A, van Grondelle R, Kennis JTM. Unraveling the Excited-State Dynamics and Light-Harvesting Functions of Xanthophylls in Light-Harvesting Complex II Using Femtosecond Stimulated Raman Spectroscopy. J Am Chem Soc 2020; 142:17346-17355. [PMID: 32878439 PMCID: PMC7564077 DOI: 10.1021/jacs.0c04619] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Photosynthesis
in plants starts with the capture of photons by
light-harvesting complexes (LHCs). Structural biology and spectroscopy
approaches have led to a map of the architecture and energy transfer
pathways between LHC pigments. Still, controversies remain regarding
the role of specific carotenoids in light-harvesting and photoprotection,
obligating the need for high-resolution techniques capable of identifying
excited-state signatures and molecular identities of the various pigments
in photosynthetic systems. Here we demonstrate the successful application
of femtosecond stimulated Raman spectroscopy (FSRS) to a multichromophoric
biological complex, trimers of LHCII. We demonstrate the application
of global and target analysis (GTA) to FSRS data and utilize it to
quantify excitation migration in LHCII trimers. This powerful combination
of techniques allows us to obtain valuable insights into structural,
electronic, and dynamic information from the carotenoids of LHCII
trimers. We report spectral and dynamical information on ground- and
excited-state vibrational modes of the different pigments, resolving
the vibrational relaxation of the carotenoids and the pathways of
energy transfer to chlorophylls. The lifetimes and spectral characteristics
obtained for the S1 state confirm that lutein 2 has a distorted conformation
in LHCII and that the lutein 2 S1 state does not transfer to chlorophylls,
while lutein 1 is the only carotenoid whose S1 state plays a significant
energy-harvesting role. No appreciable energy transfer takes place
from lutein 1 to lutein 2, contradicting recent proposals regarding
the functions of the various carotenoids (Son et al. Chem.2019, 5 (3), 575–584). Also, our results demonstrate that FSRS can be used in combination
with GTA to simultaneously study the electronic and vibrational landscapes
in LHCs and pave the way for in-depth studies of photoprotective conformations
in photosynthetic systems.
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Affiliation(s)
- Juan M Artes Vivancos
- Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.,Department of Chemistry, Kennedy College of Science, University of Massachusetts-Lowell, One University Avenue, Lowell, Massachusetts 01854, United States
| | - Ivo H M van Stokkum
- Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Francesco Saccon
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road/E1 4NS London, U.K
| | - Yusaku Hontani
- Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Miroslav Kloz
- Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Alexander Ruban
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road/E1 4NS London, U.K
| | - Rienk van Grondelle
- Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - John T M Kennis
- Department of Physics and Astronomy and LaserLaB, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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22
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Kozlov MI, Poddubnyy VV. Electron-Vibrational Spectra and Dynamics of the Lutein Molecule. J Phys Chem B 2020; 124:5780-5787. [PMID: 32573243 DOI: 10.1021/acs.jpcb.0c02511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The carotenoid molecules such as lutein play an important role in the absorption of light and the following transfer of energy during photosynthesis. However, the study of these processes by the experimental methods only is quite difficult because some of the transitions between the electronic states of carotenoids are optically forbidden and the effect of vibrational states change also must be taken into account. In the present work, electronic-vibrational states of the lutein molecule in the LHCII complex of higher plants and in the diethyl ether solution were described using the ab initio methods. For lutein of LHCII, the electronic energy transfer processes were modeled. The role of the "hot" S1 states of lutein was shown to be of great importance.
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Affiliation(s)
- Maxim I Kozlov
- Chemistry Department, Lomonosov Moscow State University, 119991 Moscow, Russia
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23
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Balevičius V, Duffy CDP. Excitation quenching in chlorophyll-carotenoid antenna systems: 'coherent' or 'incoherent'. PHOTOSYNTHESIS RESEARCH 2020; 144:301-315. [PMID: 32266612 PMCID: PMC7239839 DOI: 10.1007/s11120-020-00737-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 03/18/2020] [Indexed: 05/20/2023]
Abstract
Plants possess an essential ability to rapidly down-regulate light-harvesting in response to high light. This photoprotective process involves the formation of energy-quenching interactions between the chlorophyll and carotenoid pigments within the antenna of Photosystem II (PSII). The nature of these interactions is currently debated, with, among others, 'incoherent' or 'coherent' quenching models (or a combination of the two) suggested by a range of time-resolved spectroscopic measurements. In 'incoherent quenching', energy is transferred from a chlorophyll to a carotenoid and is dissipated due to the intrinsically short excitation lifetime of the latter. 'Coherent quenching' would arise from the quantum mechanical mixing of chlorophyll and carotenoid excited state properties, leading to a reduction in chlorophyll excitation lifetime. The key parameters are the energy gap, [Formula: see text] and the resonance coupling, J, between the two excited states. Coherent quenching will be the dominant process when [Formula: see text] i.e., when the two molecules are resonant, while the quenching will be largely incoherent when [Formula: see text] One would expect quenching to be energetically unfavorable for [Formula: see text] The actual dynamics of quenching lie somewhere between these limiting regimes and have non-trivial dependencies of both J and [Formula: see text] Using the Hierarchical Equation of Motion (HEOM) formalism we present a detailed theoretical examination of these excitation dynamics and their dependence on slow variations in J and [Formula: see text] We first consider an isolated chlorophyll-carotenoid dimer before embedding it within a PSII antenna sub-unit (LHCII). We show that neither energy transfer, nor the mixing of excited state lifetimes represent unique or necessary pathways for quenching and in fact discussing them as distinct quenching mechanisms is misleading. However, we do show that quenching cannot be switched 'on' and 'off' by fine tuning of [Formula: see text] around the resonance point, [Formula: see text] Due to the large reorganization energy of the carotenoid excited state, we find that the presence (or absence) of coherent interactions have almost no impact of the dynamics of quenching. Counter-intuitively significant quenching is present even when the carotenoid excited state lies above that of the chlorophyll. We also show that, above a rather small threshold value of [Formula: see text]quenching becomes less and less sensitive to J (since in the window [Formula: see text] the overall lifetime is independent of it). The requirement for quenching appear to be only that [Formula: see text] Although the coherent/incoherent character of the quenching can vary, the overall kinetics are likely robust with respect to fluctuations in J and [Formula: see text] This may be the basis for previous observations of NPQ with both coherent and incoherent features.
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Affiliation(s)
- Vytautas Balevičius
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - 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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24
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Son M, Pinnola A, Schlau-Cohen GS. Zeaxanthin independence of photophysics in light-harvesting complex II in a membrane environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148115. [DOI: 10.1016/j.bbabio.2019.148115] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/21/2019] [Accepted: 11/08/2019] [Indexed: 11/15/2022]
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25
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Ostroumov EE, Götze JP, Reus M, Lambrev PH, Holzwarth AR. Characterization of fluorescent chlorophyll charge-transfer states as intermediates in the excited state quenching of light-harvesting complex II. PHOTOSYNTHESIS RESEARCH 2020; 144:171-193. [PMID: 32307623 DOI: 10.1007/s11120-020-00745-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 03/31/2020] [Indexed: 05/20/2023]
Abstract
Light-harvesting complex II (LHCII) is the major antenna complex in higher plants and green algae. It has been suggested that a major part of the excited state energy dissipation in the so-called "non-photochemical quenching" (NPQ) is located in this antenna complex. We have performed an ultrafast kinetics study of the low-energy fluorescent states related to quenching in LHCII in both aggregated and the crystalline form. In both sample types the chlorophyll (Chl) excited states of LHCII are strongly quenched in a similar fashion. Quenching is accompanied by the appearance of new far-red (FR) fluorescence bands from energetically low-lying Chl excited states. The kinetics of quenching, its temperature dependence down to 4 K, and the properties of the FR-emitting states are very similar both in LHCII aggregates and in the crystal. No such FR-emitting states are found in unquenched trimeric LHCII. We conclude that these states represent weakly emitting Chl-Chl charge-transfer (CT) states, whose formation is part of the quenching process. Quantum chemical calculations of the lowest energy exciton and CT states, explicitly including the coupling to the specific protein environment, provide detailed insight into the chemical nature of the CT states and the mechanism of CT quenching. The experimental data combined with the results of the calculations strongly suggest that the quenching mechanism consists of a sequence of two proton-coupled electron transfer steps involving the three quenching center Chls 610/611/612. The FR-emitting CT states are reaction intermediates in this sequence. The polarity-controlled internal reprotonation of the E175/K179 aa pair is suggested as the switch controlling quenching. A unified model is proposed that is able to explain all known conditions of quenching or non-quenching of LHCII, depending on the environment without invoking any major conformational changes of the protein.
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Affiliation(s)
- Evgeny E Ostroumov
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim a. d. Ruhr, Germany
- Quantum Matter Institute, University of British Columbia, 2355 East Mall, Vancouver, V6T 1Z1, Canada
| | - Jan P Götze
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim a. d. Ruhr, Germany
- Institut für Chemie und Biochemie, Freie Universität Berlin, Arnimallee 22, 14195, Berlin, Germany
| | - Michael Reus
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim a. d. Ruhr, Germany
| | - Petar H Lambrev
- Biological Research Centre, Temesvári krt. 62, Szeged, 6726, Hungary
| | - Alfred R Holzwarth
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470, Mülheim a. d. Ruhr, Germany.
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26
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Liguori N, Croce R, Marrink SJ, Thallmair S. Molecular dynamics simulations in photosynthesis. PHOTOSYNTHESIS RESEARCH 2020; 144:273-295. [PMID: 32297102 PMCID: PMC7203591 DOI: 10.1007/s11120-020-00741-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/24/2020] [Indexed: 05/12/2023]
Abstract
Photosynthesis is regulated by a dynamic interplay between proteins, enzymes, pigments, lipids, and cofactors that takes place on a large spatio-temporal scale. Molecular dynamics (MD) simulations provide a powerful toolkit to investigate dynamical processes in (bio)molecular ensembles from the (sub)picosecond to the (sub)millisecond regime and from the Å to hundreds of nm length scale. Therefore, MD is well suited to address a variety of questions arising in the field of photosynthesis research. In this review, we provide an introduction to the basic concepts of MD simulations, at atomistic and coarse-grained level of resolution. Furthermore, we discuss applications of MD simulations to model photosynthetic systems of different sizes and complexity and their connection to experimental observables. Finally, we provide a brief glance on which methods provide opportunities to capture phenomena beyond the applicability of classical MD.
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Affiliation(s)
- Nicoletta Liguori
- Department of Physics and Astronomy and Institute for Lasers, Life and Biophotonics, Faculty of Sciences, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
| | - Roberta Croce
- Department of Physics and Astronomy and Institute for Lasers, Life and Biophotonics, Faculty of Sciences, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Sebastian Thallmair
- Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
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27
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Observation of dissipative chlorophyll-to-carotenoid energy transfer in light-harvesting complex II in membrane nanodiscs. Nat Commun 2020; 11:1295. [PMID: 32157079 PMCID: PMC7064482 DOI: 10.1038/s41467-020-15074-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 02/17/2020] [Indexed: 11/08/2022] Open
Abstract
Plants prevent photodamage under high light by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics to the protein structure. The mechanisms of dissipation remain debated, largely due to two challenges. First, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Second, experiments have been performed in detergent, which can induce non-native conformations, or in vivo, where contributions from homologous antenna complexes cannot be disentangled. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, LHCII, in a near-native membrane. Our data provide evidence that the membrane enhances two dissipative pathways, one of which is a previously uncharacterized chlorophyll-to-carotenoid energy transfer. Our results highlight the sensitivity of the photophysics to local environment, which may control the balance between light harvesting and dissipation in vivo.
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Jakučionis M, Mancal T, Abramavičius D. Modeling irreversible molecular internal conversion using the time-dependent variational approach with sD2 ansatz. Phys Chem Chem Phys 2020; 22:8952-8962. [DOI: 10.1039/d0cp01092h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A model of irreversible molecular internal conversion dynamics due to molecular thermal energy dissipation to the bath is presented.
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Affiliation(s)
- Mantas Jakučionis
- Institute of Chemical Physics
- Vilnius University
- LT-10222 Vilnius
- Lithuania
| | - Tomas Mancal
- Faculty of Mathematics and Physics
- Charles University
- 121 16 Prague
- Czech Republic
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Wei T, Balevičius V, Polívka T, Ruban AV, Duffy CDP. How carotenoid distortions may determine optical properties: lessons from the Orange Carotenoid Protein. Phys Chem Chem Phys 2019; 21:23187-23197. [PMID: 31612872 DOI: 10.1039/c9cp03574e] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carotenoids in photosynthetic proteins carry out the dual function of harvesting light and defending against photo-damage by quenching excess energy. The latter involves the low-lying, dark, excited state labelled S1. Here "dark" means optically-forbidden, a property that is often attributed to molecular symmetry, which leads to speculation that its optical properties may be strongly-perturbed by structural distortions. This has been both explicitly and implicitly proposed as an important feature of photo-protective energy quenching. Here we present a theoretical analysis of the relationship between structural distortions and S1 optical properties. We outline how S1 is dark not because of overall geometric symmetry but because of a topological symmetry related to bond length alternation in the conjugated backbone. Taking the carotenoid echinenone as an example and using a combination of molecular dynamics, quantum chemistry, and the theory of spectral lineshapes, we show that distortions that break this symmetry are extremely stiff. They are therefore absent in solution and only marginally present in even a very highly-distorted protein binding pocket such as in the Orange Carotenoid Protein (OCP). S1 remains resolutely optically-forbidden despite any breaking of bulk molecular symmetry by the protein environment. However, rotations of partially conjugated end-rings can result in fine tuning of the S1 transition density which may exert some influence on interactions with neighbouring chromophores.
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Affiliation(s)
- Tiejun Wei
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK.
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Daskalakis V, Maity S, Hart CL, Stergiannakos T, Duffy CDP, Kleinekathöfer U. Structural Basis for Allosteric Regulation in the Major Antenna Trimer of Photosystem II. J Phys Chem B 2019; 123:9609-9615. [DOI: 10.1021/acs.jpcb.9b09767] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Vangelis Daskalakis
- Department of Environmental Science and Technology, Cyprus University of Technology, 30 Archbishop Kyprianou Street, 3603, Limassol, Cyprus
| | - Sayan Maity
- Department of Physics & Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Cameron Lewis Hart
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Taxiarchis Stergiannakos
- Department of Environmental Science and Technology, Cyprus University of Technology, 30 Archbishop Kyprianou Street, 3603, Limassol, Cyprus
| | - Christopher D. P. Duffy
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Ulrich Kleinekathöfer
- Department of Physics & Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
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31
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Hancock AM, Meredith SA, Connell SD, Jeuken LJC, Adams PG. Proteoliposomes as energy transferring nanomaterials: enhancing the spectral range of light-harvesting proteins using lipid-linked chromophores. NANOSCALE 2019; 11:16284-16292. [PMID: 31465048 DOI: 10.1039/c9nr04653d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bio-hybrid nanomaterials have great potential for combining the most desirable aspects of biomolecules and the contemporary concepts of nanotechnology to create highly efficient light-harvesting materials. Light-harvesting proteins are optimized to absorb and transfer solar energy with remarkable efficiency but have a spectral range that is limited by their natural pigment complement. Herein, we present the development of model membranes ("proteoliposomes") in which the absorption range of the membrane protein Light-Harvesting Complex II (LHCII) is effectively enhanced by the addition of lipid-tethered Texas Red (TR) chromophores. Energy transfer from TR to LHCII is observed with up to 94% efficiency and increased LHCII fluorescence of up to three-fold when excited in the region of lowest natural absorption. The new self-assembly procedure offers the modularity to control the concentrations incorporated of TR and LHCII, allowing energy transfer and fluorescence to be tuned. Fluorescence Lifetime Imaging Microscopy provides single-proteoliposome-level quantification of energy transfer efficiency and confirms that functionality is retained on surfaces. Designer proteoliposomes could act as a controllable light-harvesting nanomaterial and are a promising step in the development of bio-hybrid light-harvesting systems.
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Affiliation(s)
- Ashley M Hancock
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Sophie A Meredith
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Simon D Connell
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Lars J C Jeuken
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK and School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Peter G Adams
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK. and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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Cupellini L, Bondanza M, Nottoli M, Mennucci B. Successes & challenges in the atomistic modeling of light-harvesting and its photoregulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1861:148049. [PMID: 31386831 DOI: 10.1016/j.bbabio.2019.07.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 07/10/2019] [Accepted: 07/15/2019] [Indexed: 12/21/2022]
Abstract
Light-harvesting is a crucial step of photosynthesis. Its mechanisms and related energetics have been revealed by a combination of experimental investigations and theoretical modeling. The success of theoretical modeling is largely due to the application of atomistic descriptions combining quantum chemistry, classical models and molecular dynamics techniques. Besides the important achievements obtained so far, a complete and quantitative understanding of how the many different light-harvesting complexes exploit their structural specificity is still missing. Moreover, many questions remain unanswered regarding the mechanisms through which light-harvesting is regulated in response to variable light conditions. Here we show that, in both fields, a major role will be played once more by atomistic descriptions, possibly generalized to tackle the numerous time and space scales on which the regulation takes place: going from the ultrafast electronic excitation of the multichromophoric aggregate, through the subsequent conformational changes in the embedding protein, up to the interaction between proteins.
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Affiliation(s)
- Lorenzo Cupellini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
| | - Mattia Bondanza
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
| | - Michele Nottoli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, Pisa 56124, Italy.
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Single-molecule microscopy studies of LHCII enriched in Vio or Zea. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:499-507. [DOI: 10.1016/j.bbabio.2019.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 11/20/2022]
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Microsecond and millisecond dynamics in the photosynthetic protein LHCSR1 observed by single-molecule correlation spectroscopy. Proc Natl Acad Sci U S A 2019; 116:11247-11252. [PMID: 31101718 DOI: 10.1073/pnas.1821207116] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Biological systems are subjected to continuous environmental fluctuations, and therefore, flexibility in the structure and function of their protein building blocks is essential for survival. Protein dynamics are often local conformational changes, which allows multiple dynamical processes to occur simultaneously and rapidly in individual proteins. Experiments often average over these dynamics and their multiplicity, preventing identification of the molecular origin and impact on biological function. Green plants survive under high light by quenching excess energy, and Light-Harvesting Complex Stress Related 1 (LHCSR1) is the protein responsible for quenching in moss. Here, we expand an analysis of the correlation function of the fluorescence lifetime by improving the estimation of the lifetime states and by developing a multicomponent model correlation function, and we apply this analysis at the single-molecule level. Through these advances, we resolve previously hidden rapid dynamics, including multiple parallel processes. By applying this technique to LHCSR1, we identify and quantitate parallel dynamics on hundreds of microseconds and tens of milliseconds timescales, likely at two quenching sites within the protein. These sites are individually controlled in response to fluctuations in sunlight, which provides robust regulation of the light-harvesting machinery. Considering our results in combination with previous structural, spectroscopic, and computational data, we propose specific pigments that serve as the quenching sites. These findings, therefore, provide a mechanistic basis for quenching, illustrating the ability of this method to uncover protein function.
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Ab initio model for the chlorophyll-lutein exciton coupling in the LHCII complex. Biophys Chem 2019; 246:16-24. [DOI: 10.1016/j.bpc.2019.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/27/2018] [Accepted: 01/02/2019] [Indexed: 11/20/2022]
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Fox KF, Ünlü C, Balevičius V, Ramdour BN, Kern C, Pan X, Li M, van Amerongen H, Duffy CD. A possible molecular basis for photoprotection in the minor antenna proteins of plants. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:471-481. [DOI: 10.1016/j.bbabio.2018.03.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/19/2018] [Accepted: 03/28/2018] [Indexed: 12/21/2022]
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Daskalakis V. Protein-protein interactions within photosystem II under photoprotection: the synergy between CP29 minor antenna, subunit S (PsbS) and zeaxanthin at all-atom resolution. Phys Chem Chem Phys 2018; 20:11843-11855. [PMID: 29658553 DOI: 10.1039/c8cp01226a] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The assembly and disassembly of protein complexes within cells are crucial life-sustaining processes. In photosystem II (PSII) of higher plants, there is a delicate yet obscure balance between light harvesting and photo-protection under fluctuating light conditions, that involves protein-protein complexes. Recent breakthroughs in molecular dynamics (MD) simulations are combined with new approaches herein to provide structural and energetic insight into such a complex between the CP29 minor antenna and the PSII subunit S (PsbS). The microscopic model involves extensive sampling of bound and dissociated states at atomic resolution in the presence of photo-protective zeaxanthin (Zea), and reveals well defined protein-protein cross-sections. The complex is placed within PSII, and macroscopic connections are emerging (PsbS-CP29-CP24-CP47) along the energy transfer pathways from the antenna to the PSII core. These connections explain macroscopic observations in the literature, while the previously obscured atomic scale details are now revealed. The implications of these findings are discussed in the context of the Non-Photochemical Quenching (NPQ) of chlorophyll fluorescence, the down-regulatory mechanism of photosynthesis, that enables the protection of PSII against excess excitation load. Zea is found at the PsbS-CP29 cross-section and a pH-dependent equilibrium between PsbS dimer/monomers and the PsbS-CP29 dissociation/association is identified as the target for engineering tolerant plants with increased crop and biomass yields. Finally, the new MD based approaches can be used to probe protein-protein interactions in general, and the PSII structure provided can initiate large scale molecular simulations of the photosynthetic apparatus, under NPQ conditions.
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Affiliation(s)
- Vangelis Daskalakis
- Department of Environmental Science and Technology, Cyprus University of Technology (CUT), 30 Archbishop Kyprianou Str., 3603, Limassol, Cyprus.
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Daskalakis V, Papadatos S. The Photosystem II Subunit S under Stress. Biophys J 2018; 113:2364-2372. [PMID: 29211990 DOI: 10.1016/j.bpj.2017.09.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 08/29/2017] [Accepted: 09/29/2017] [Indexed: 01/08/2023] Open
Abstract
Nonphotochemical quenching is the protective mechanism against overexcitation of photosystem II, triggered by excess ΔpH in photosynthetic membranes. The light-harvesting complexes (LHCs), the de-epoxidation of violaxanthin to zeaxanthin, and the photosystem II subunit S (PsbS) work in synergy for an optimized multilevel response. Understanding the fine details of this synergy has proven challenging to scientific research. Here, we employ large-scale, all-atom molecular simulations and beyond experimental insight, we proceed a step further in identifying the PsbS dynamics that could possibly be associated with this synergy. For the first time, to our knowledge, we probe the distinct behavior of PsbS under ΔpH that probes the details of the potential dimer-to-monomer transition, and in a violaxanthin/zeaxanthin-rich membrane, at an all-atom resolution. We propose that the lumen-exposed residues, threonine 162 and glutamic acid 173, form stabilizing hydrogen bonds between the PsbS monomers only at high lumen pH, whereas at low pH (excess ΔpH) this interaction is lost, and leads to higher flexibility of the protein and potentially to the dimer-to-monomer transition. Lastly, we discuss how conformational changes under the presence of ΔpH/zeaxanthin are related to the PsbS role in the current nonphotochemical quenching model in the literature. For the latter, we probe a PsbS-monomeric LHCII association. The association is proposed to potentially alter the monomeric LHCII sensitivity to ΔpH by changing the pKa values of interacting LHCII residues. This serves as an example where protonation-ligation events enhance protein-protein interactions fundamental to many life processes.
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Affiliation(s)
- Vangelis Daskalakis
- Department of Environmental Science and Technology, Cyprus University of Technology, Limassol, Cyprus.
| | - Sotiris Papadatos
- Department of Environmental Science and Technology, Cyprus University of Technology, Limassol, Cyprus
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Tutkus M, Chmeliov J, Rutkauskas D, Ruban AV, Valkunas L. Influence of the Carotenoid Composition on the Conformational Dynamics of Photosynthetic Light-Harvesting Complexes. J Phys Chem Lett 2017; 8:5898-5906. [PMID: 29140702 DOI: 10.1021/acs.jpclett.7b02634] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nonphotochemical quenching (NPQ) is the major self-regulatory mechanism of green plants, performed on a molecular level to protect them from an overexcitation during the direct sunlight. It is believed that NPQ becomes available due to conformational dynamics of the light-harvesting photosynthetic complexes and involves a direct participation of carotenoids. In this work, we perform a single-molecule microscopy on major light-harvesting complexes (LHCII) from different Arabidopsis thaliana mutants exhibiting various carotenoid composition. We show how the distinct carotenoids affect the dynamics of the conformational switching between multiple coexisting light-emitting states of LHCII and demonstrate that properties of the quenched conformation are not influenced by the particular carotenoids available in LHCII. We also discuss the possible origin of different conformational states and relate them to the fluorescence decay kinetics observed during the bulk measurements.
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Affiliation(s)
- Marijonas Tutkus
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology , Saulėtekio Avenue 3, LT-10257 Vilnius, Lithuania
| | - Jevgenij Chmeliov
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology , Saulėtekio Avenue 3, LT-10257 Vilnius, Lithuania
- Institute of Chemical Physics, Faculty of Physics, Vilnius University , Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania
| | - Danielis Rutkauskas
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology , Saulėtekio Avenue 3, LT-10257 Vilnius, Lithuania
| | - Alexander V Ruban
- The School of Biological and Chemical Sciences, Queen Mary, University of London , Mile End Road, London E1 4NS, United Kingdom
| | - Leonas Valkunas
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology , Saulėtekio Avenue 3, LT-10257 Vilnius, Lithuania
- Institute of Chemical Physics, Faculty of Physics, Vilnius University , Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania
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Balevičius V, Fox KF, Bricker WP, Jurinovich S, Prandi IG, Mennucci B, Duffy CDP. Fine control of chlorophyll-carotenoid interactions defines the functionality of light-harvesting proteins in plants. Sci Rep 2017; 7:13956. [PMID: 29066753 PMCID: PMC5655323 DOI: 10.1038/s41598-017-13720-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/26/2017] [Indexed: 11/08/2022] Open
Abstract
Photosynthetic antenna proteins can be thought of as "programmed solvents", which bind pigments at specific mutual orientations, thus tuning the overall energetic landscape and ensuring highly efficient light-harvesting. While positioning of chlorophyll cofactors is well understood and rationalized by the principle of an "energy funnel", the carotenoids still pose many open questions. Particularly, their short excited state lifetime (<25 ps) renders them potential energy sinks able to compete with the reaction centers and drastically undermine light-harvesting efficiency. Exploration of the orientational phase-space revealed that the placement of central carotenoids minimizes their interaction with the nearest chlorophylls in the plant antenna complexes LHCII, CP26, CP29 and LHCI. At the same time we show that this interaction is highly sensitive to structural perturbations, which has a profound effect on the overall lifetime of the complex. This links the protein dynamics to the light-harvesting regulation in plants by the carotenoids.
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Affiliation(s)
- Vytautas Balevičius
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Kieran F Fox
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - William P Bricker
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Sandro Jurinovich
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via G. Moruzzi 13, Pisa, 56124, Italy
| | - Ingrid G Prandi
- Department of Chemistry, Federal University of Lavras, 37200-000, Lavras, Brazil
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense, Military Institute of Engineering, Praça Gen, Tibúrcio, 80, Rio de Janeiro, Brazil
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via G. Moruzzi 13, Pisa, 56124, Italy
| | - Christopher D P Duffy
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK.
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