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Gritsi CS, Sarmas E, Daskalakis V, Kotzabasis K. Acclimation mechanism of microalgal photosynthetic apparatus under low atmospheric pressures - new astrobiological perspectives in a Mars-like atmosphere. FUNCTIONAL PLANT BIOLOGY : FPB 2024; 51:FP24058. [PMID: 38902906 DOI: 10.1071/fp24058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 05/25/2024] [Indexed: 06/22/2024]
Abstract
This study reveals a new acclimation mechanism of the eukaryotic unicellular green alga Chlorella vulgaris in terms of the effect of varying atmospheric pressures on the structure and function of its photosynthetic apparatus using fluorescence induction measurements (JIP-test). The results indicate that low (400mbar) and extreme low (2 atmosphere (simulating the Mars atmosphere), reveals that the impact of extremely low atmospheric pressure on PQ mobility within the photosynthetic membrane, coupled with the low density of an almost 100% CO2 Mars-like atmosphere, results to a similar photosynthetic efficiency to that on Earth. These findings pave the way for the identification of novel functional acclimation mechanisms of microalgae to extreme environments that are vastly distinct from those found on Earth.
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Affiliation(s)
| | - Evangelos Sarmas
- Department of Biology, University of Crete, Voutes University Campus, Heraklion, Crete GR 70013, Greece
| | - Vangelis Daskalakis
- Department of Chemical Engineering, School of Engineering, University of Patras, Patras GR 26504, Greece
| | - Kiriakos Kotzabasis
- Department of Biology, University of Crete, Voutes University Campus, Heraklion, Crete GR 70013, Greece
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2
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Gelzinis A, Chmeliov J, Tutkus M, Vitulskienė E, Franckevičius M, Büchel C, Robert B, Valkunas L. Fluorescence quenching in aggregates of fucoxanthin-chlorophyll protein complexes: Interplay of fluorescing and dark states. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2024; 1865:149030. [PMID: 38163538 DOI: 10.1016/j.bbabio.2023.149030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/29/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
Diatoms, a major group of algae, account for about a quarter of the global primary production on Earth. These photosynthetic organisms face significant challenges due to light intensity variations in their underwater habitat. To avoid photodamage, they have developed very efficient non-photochemical quenching (NPQ) mechanisms. These mechanisms originate in their light-harvesting antenna - the fucoxanthin-chlorophyll protein (FCP) complexes. Spectroscopic studies of NPQ in vivo are often hindered by strongly overlapping signals from the photosystems and their antennae. Fortunately, in vitro FCP aggregates constitute a useful model system to study fluorescence (FL) quenching in diatoms. In this work, we present streak-camera FL measurements on FCPa and FCPb complexes, isolated from a centric diatom Cyclotella meneghiniana, and their aggregates. We find that spectra of non-aggregated FCP are dominated by a single fluorescing species, but the FL spectra of FCP aggregates additionally contain contributions from a redshifted emissive state. We relate this red state to a charge transfer state between chlorophyll c and chlorophyll a molecules. The FL quenching, on the other hand, is due to an additional dark state that involves incoherent energy transfer to the fucoxanthin carotenoids. Overall, the global picture of energy transfer and quenching in FCP aggregates is very similar to that of major light-harvesting complexes in higher plants (LHCII), but microscopic details between FCPs and LHCIIs differ significantly.
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Affiliation(s)
- Andrius Gelzinis
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Ave. 3, 10257 Vilnius, Lithuania; Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Ave. 9-III, 10222 Vilnius, Lithuania
| | - Jevgenij Chmeliov
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Ave. 3, 10257 Vilnius, Lithuania; Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Ave. 9-III, 10222 Vilnius, Lithuania
| | - Marijonas Tutkus
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Ave. 3, 10257 Vilnius, Lithuania; Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio Ave. 7, 10257 Vilnius, Lithuania
| | - Ernesta Vitulskienė
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Ave. 3, 10257 Vilnius, Lithuania
| | - Marius Franckevičius
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Ave. 3, 10257 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
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Ave. 3, 10257 Vilnius, Lithuania; Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Ave. 9-III, 10222 Vilnius, Lithuania.
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3
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Maity S, Daskalakis V, Jansen TLC, Kleinekathöfer U. Electric Field Susceptibility of Chlorophyll c Leads to Unexpected Excitation Dynamics in the Major Light-Harvesting Complex of Diatoms. J Phys Chem Lett 2024; 15:2499-2510. [PMID: 38410961 PMCID: PMC10926154 DOI: 10.1021/acs.jpclett.3c03241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/04/2024] [Accepted: 02/12/2024] [Indexed: 02/28/2024]
Abstract
Diatoms are one of the most abundant photosynthetic organisms on earth and contribute largely to atmospheric oxygen production. They contain fucoxanthin and chlorophyll-a/c binding proteins (FCPs) as light-harvesting complexes with a remarkable adaptation to the fluctuating light on ocean surfaces. To understand the basis of the photosynthetic process in diatoms, the excitation energy funneling within FCPs must be probed. A state-of-the-art multiscale analysis within a quantum mechanics/molecular mechanics framework has been employed. To this end, the chlorophyll (Chl) excitation energies within the FCP complex from the diatom Phaeodactylum tricornutum have been determined. The Chl-c excitation energies were found to be 5-fold more susceptible to electric fields than those of Chl-a pigments and thus are significantly lower in FCP than in organic solvents. This finding challenges the general belief that the excitation energy of Chl-c is always higher than that of Chl-a in FCP proteins and reveals that Chl-c molecules are much more sensitive to electric fields within protein scaffolds than in Chl-a pigments. The analysis of the linear absorption spectrum and the two-dimensional electronic spectra of the FCP complex strongly supports these findings and allows us to study the excitation transfer within the FCP complex.
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Affiliation(s)
- Sayan Maity
- School
of Science, Constructor University, Campus Ring 1, 28759 Bremen, Germany
| | - Vangelis Daskalakis
- Department
of Chemical Engineering, School of Engineering,
University of Patras, Patras 26504, Greece
| | - Thomas L. C. Jansen
- Zernike
Institute for Advanced Materials, University
of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
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4
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Andreou C, Tselios C, Ioannou A, Varotsis C. Probing the Fucoxanthin-Chlorophyll a/ c-Binding Proteins (FCPs) of the Marine Diatom Fragilariopsis sp. by Resonance Raman Spectroscopy. J Phys Chem B 2023; 127:9014-9020. [PMID: 37819729 PMCID: PMC10614187 DOI: 10.1021/acs.jpcb.3c04346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/21/2023] [Indexed: 10/13/2023]
Abstract
We report resonance Raman spectra of the light-harvesting fucoxanthin-chlorophyll a/c-binding proteins (FCPs) of marine diatom Fragilariopsis sp. The Raman shifts in the 15N-isotope-enriched diatom provide the first spectroscopic evidence for the characterization of the Ca-N marker bands and, thus, of the penta- and hexacoordinated states of chlorophylls a/c in the FCPs. Under 405 and 442 nm Raman excitations, all of the marker bands of Chl a/c are observed and the isotope-based assignments provide new information concerning the structure of Chls a/c in the FCPs and their interactions with the protein environment. Therefore, the Raman spectrum at 405 nm originates from the π-π* transitions of Chl a/c and not from a different, non π-π* electronic transition, as previously reported (BBA Bioenergetics, 2010, 1797, 1647-1656). Based on the 15N isotope shifts of the Ca-N and in conjunction with other marker bands, two distinct conformations of five- and six-coordinated Chl a and Chl c are observed. In addition, two keto carbonyls were observed at 1679 (strong H-bonded) and 1691 cm-1 (weak H-bonded) in both the 405 and 442 nm Raman spectra, respectively. Collectively, the results provide solid evidence of the nature of the vibrational modes of the active Chl a/c photosynthetic pigments in the FCPs.
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Affiliation(s)
- Charalampos Andreou
- Department of Chemical Engineering, Cyprus University of Technology, 95 Eirinis Str., Lemesos 3603, Cyprus
| | - Charalampos Tselios
- Department of Chemical Engineering, Cyprus University of Technology, 95 Eirinis Str., Lemesos 3603, Cyprus
| | - Aristos Ioannou
- Department of Chemical Engineering, Cyprus University of Technology, 95 Eirinis Str., Lemesos 3603, Cyprus
| | - Constantinos Varotsis
- Department of Chemical Engineering, Cyprus University of Technology, 95 Eirinis Str., Lemesos 3603, Cyprus
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5
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Diaz BP, Zelzion E, Halsey K, Gaube P, Behrenfeld M, Bidle KD. Marine phytoplankton downregulate core photosynthesis and carbon storage genes upon rapid mixed layer shallowing. THE ISME JOURNAL 2023:10.1038/s41396-023-01416-x. [PMID: 37156837 DOI: 10.1038/s41396-023-01416-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 04/03/2023] [Accepted: 04/13/2023] [Indexed: 05/10/2023]
Abstract
Marine phytoplankton are a diverse group of photoautotrophic organisms and key mediators in the global carbon cycle. Phytoplankton physiology and biomass accumulation are closely tied to mixed layer depth, but the intracellular metabolic pathways activated in response to changes in mixed layer depth remain less explored. Here, metatranscriptomics was used to characterize the phytoplankton community response to a mixed layer shallowing (from 233 to 5 m) over the course of two days during the late spring in the Northwest Atlantic. Most phytoplankton genera downregulated core photosynthesis, carbon storage, and carbon fixation genes as the system transitioned from a deep to a shallow mixed layer and shifted towards catabolism of stored carbon supportive of rapid cell growth. In contrast, phytoplankton genera exhibited divergent transcriptional patterns for photosystem light harvesting complex genes during this transition. Active virus infection, taken as the ratio of virus to host transcripts, increased in the Bacillariophyta (diatom) phylum and decreased in the Chlorophyta (green algae) phylum upon mixed layer shallowing. A conceptual model is proposed to provide ecophysiological context for our findings, in which integrated light limitation and lower division rates during transient deep mixing are hypothesized to disrupt resource-driven, oscillating transcript levels related to photosynthesis, carbon fixation, and carbon storage. Our findings highlight shared and unique transcriptional response strategies within phytoplankton communities acclimating to the dynamic light environment associated with transient deep mixing and shallowing events during the annual North Atlantic bloom.
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Affiliation(s)
- Ben P Diaz
- Department of Marine and Coastal Science, Rutgers University, New Brunswick, NJ, 08901, USA
- Biotechnology & Bioengineering, Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Ehud Zelzion
- Office of Advanced Research Computing, Rutgers University, Piscataway, NJ, 08854, USA
| | - Kimberly Halsey
- Department of Microbiology, Oregon State University, Corvallis, OR, 97331, USA
| | - Peter Gaube
- Applied Physics Laboratory, University of Washington, Seattle, WA, 98105, USA
| | - Michael Behrenfeld
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Kay D Bidle
- Department of Marine and Coastal Science, Rutgers University, New Brunswick, NJ, 08901, USA.
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6
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Agostini A, Bína D, Carbonera D, Litvín R. Conservation of triplet-triplet energy transfer photoprotective pathways in fucoxanthin chlorophyll-binding proteins across algal lineages. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148935. [PMID: 36379269 DOI: 10.1016/j.bbabio.2022.148935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/18/2022] [Accepted: 11/07/2022] [Indexed: 11/14/2022]
Abstract
Detailed information on the photo-generated triplet states of diatom and haptophyte Fucoxanthin Chlorophyll-binding Proteins (FCPs and E-FCPs, respectively) have been obtained from a combined spectroscopic investigation involving Transient Absorption and Time-Resolved Electron Paramagnetic Resonance. Pennate diatom Phaeodactylum tricornutum FCP shows identical photoprotective Triplet-Triplet Energy Transfer (TTET) pathways to the previously investigated centric diatom Cyclotella meneghiniana FCP, with the same two chlorophyll a-fucoxanthin pairs that involve the fucoxanthins in sites Fx301 and Fx302 contributing to TTET in both diatom groups. In the case of the haptophyte Emilianina huxleyi E-FCP, only one of the two chlorophyll a-fucoxanthins pairs observed in diatoms, the one involving chlorophyll a409 and Fx301, has been shown to be active in TTET. Furthermore, despite the marked change in the pigment content of E-FCP with growth light intensity, the TTET pathway is not affected. Thus, our comparative investigation of FCPs revealed a photoprotective TTET pathway shared within these classes involving the fucoxanthin in site Fx301, a site exposed to the exterior of the antenna monomer that has no equivalent in Light-Harvesting Complexes from the green lineage.
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Affiliation(s)
- Alessandro Agostini
- Biology Centre, Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 1160/31, 370 05 České Budějovice, Czech Republic.
| | - David Bína
- Biology Centre, Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 1160/31, 370 05 České Budějovice, Czech Republic; Institute of Chemistry, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Radek Litvín
- Biology Centre, Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 1160/31, 370 05 České Budějovice, Czech Republic; Institute of Chemistry, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic.
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7
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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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8
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Grüning G, Wong SY, Gerhards L, Schuhmann F, Kattnig DR, Hore PJ, Solov’yov IA. Effects of Dynamical Degrees of Freedom on Magnetic Compass Sensitivity: A Comparison of Plant and Avian Cryptochromes. J Am Chem Soc 2022; 144:22902-22914. [DOI: 10.1021/jacs.2c06233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Affiliation(s)
- Gesa Grüning
- Department of Physics, Carl von Ossietzky University, Carl-von-Ossietzky-Street 9-11, 26129 Oldenburg, Germany
| | - Siu Ying Wong
- Department of Physics, Carl von Ossietzky University, Carl-von-Ossietzky-Street 9-11, 26129 Oldenburg, Germany
| | - Luca Gerhards
- Department of Physics, Carl von Ossietzky University, Carl-von-Ossietzky-Street 9-11, 26129 Oldenburg, Germany
| | - Fabian Schuhmann
- Department of Physics, Carl von Ossietzky University, Carl-von-Ossietzky-Street 9-11, 26129 Oldenburg, Germany
| | - Daniel R. Kattnig
- Department of Physics and Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, U.K
| | - P. J. Hore
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, U.K
| | - Ilia A. Solov’yov
- Department of Physics, Carl von Ossietzky University, Carl-von-Ossietzky-Street 9-11, 26129 Oldenburg, Germany
- Research Center for Neurosensory Science, Carl von Ossietzky Universität Oldenburg, 26111 Oldenburg, Germany
- Center for Nanoscale Dynamics (CENAD), Carl von Ossietzky Universität Oldenburg, Institut für Physik, Ammerländer Heerstreet 114-118, 26129 Oldenburg, Germany
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9
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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: 3] [Impact Index Per Article: 1.5] [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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Cignoni E, Cupellini L, Mennucci B. A fast method for electronic couplings in embedded multichromophoric systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:304004. [PMID: 35552268 DOI: 10.1088/1361-648x/ac6f3c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Electronic couplings are key to understanding exciton delocalization and transport in natural and artificial light harvesting processes. We develop a method to compute couplings in multichromophoric aggregates embedded in complex environments without running expensive quantum chemical calculations. We use a transition charge approximation to represent the quantum mechanical transition densities of the chromophores and an atomistic and polarizable classical model to describe the environment atoms. We extend our framework to estimate transition charges directly from the chromophore geometry, i.e., bypassing completely the quantum mechanical calculations using a regression approach. The method allows to rapidly compute accurate couplings for a large number of geometries along molecular dynamics trajectories.
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Affiliation(s)
- Edoardo Cignoni
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, via G. Moruzzi 13, 56124, Pisa, Italy
| | - Lorenzo Cupellini
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, via G. Moruzzi 13, 56124, Pisa, Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, via G. Moruzzi 13, 56124, Pisa, Italy
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11
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Tselios C, Varotsis C. Evidence for reversible light-dependent transitions in the photosynthetic pigments of diatoms. RSC Adv 2022; 12:31555-31563. [PMID: 36380945 PMCID: PMC9631684 DOI: 10.1039/d2ra05284a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
Marine diatoms contribute to oxygenic photosynthesis and carbon fixation and handle large changes under variable light intensity on a regular basis. The unique light-harvesting apparatus of diatoms are the fucoxanthin–chlorophyll a/c-binding proteins (FCPs). Here, we show the enhancement of chlorophyll a/c (Chl a/c), fucoxanthin (Fx), and diadinoxanthin (Dd) marker bands in the Raman spectra of the centric diatom T. pseudonana, which allows distinction of the pigment content in the cells grown under low- (LL) and high-light (HL) intensity at room temperature. Reversible LL–HL dependent conformations of Chl c, characteristic of two conformations of the porphyrin macrocycle, and the presence of five- and six-coordinated Chl a/c with weak axial ligands are observed in the Raman data. Under HL the energy transfer from Chl c to Chl a is reduced and that from the red-shifted Fxs is minimal. Therefore, Chl c and the blue-shifted Fxs are the only contributors to the energy transfer pathways under HL and the blue- to red-shifted Fxs energy transfer pathway characteristic of the LL is inactive. The results indicate that T. pseudonana can redirect its function from light harvesting to energy-quenching state, and reversibly to light-harvesting upon subsequent illumination to LL by reproducing the red-shifted Fxs and decrease the number of Dds. The LL to HL reversible transitions are accompanied by structural modifications of Chl a/c and the lack of the red-shifted Fxs. A reversible light-intensity behavior of Dds and Fxs composition in the cells of T. pseudonana. The observed LL to HL reversible transitions are accompanied by structural modifications of Chls a/c and the lack of the red-shifted Fxs.![]()
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Affiliation(s)
- Charalampos Tselios
- Cyprus University of Technology, Department of Chemical Engineering, Lemesos, Cyprus
| | - Constantinos Varotsis
- Cyprus University of Technology, Department of Chemical Engineering, Lemesos, Cyprus
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