1
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Saga Y, Yamashita M, Masaoka Y, Hidaka T, Imanishi M, Kimura Y, Nagasawa Y. Excitation Energy Transfer from Bacteriochlorophyll b in the B800 Site to B850 Bacteriochlorophyll a in Light-Harvesting Complex 2. J Phys Chem B 2021; 125:2009-2017. [PMID: 33605728 DOI: 10.1021/acs.jpcb.0c09605] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Control of the spectral overlap between energy donors and acceptors provides insight into excitation energy transfer (EET) mechanisms in photosynthetic light-harvesting proteins. Substitution of energy-donating B800 bacteriochlorophyll (BChl) a with other pigments in the light-harvesting complex 2 (LH2) of purple photosynthetic bacteria has been extensively performed; however, most studies on the B800 substitution have focused on the decrease in the spectral overlap integral with energy-accepting B850 BChl a by reconstitution of chlorophylls into the B800 site. Here, we reconstitute BChl b into the B800 site of the LH2 protein from Rhodoblastus acidophilus to increase the spectral overlap with B850 BChl a. BChl b in the B800 site had essentially the same hydrogen-bonding pattern as B800 BChl a, whereas it showed a red-shifted Qy absorption band at 831 nm. The EET rate from BChl b to B850 BChl a in the reconstituted LH2 was similar to that of native LH2 despite the red shift of the Qy band of the energy donor. These results demonstrate the importance of the contribution of the density of excitation states of the B850 circular assembly, which incorporates higher lying optically forbidden states, to intracomplex EET in LH2.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Madoka Yamashita
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yuto Masaoka
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Tsubasa Hidaka
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Michie Imanishi
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yukihiro Kimura
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yutaka Nagasawa
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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2
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Bourne Worster S, Stross C, Vaughan FMWC, Linden N, Manby FR. Structure and Efficiency in Bacterial Photosynthetic Light Harvesting. J Phys Chem Lett 2019; 10:7383-7390. [PMID: 31714789 DOI: 10.1021/acs.jpclett.9b02625] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Photosynthetic organisms use networks of chromophores to absorb and deliver solar energy to reaction centers. We present a detailed model of the light-harvesting complexes in purple bacteria, including explicit interaction with sunlight, radiative and nonradiative energy loss, and dephasing and thermalizing effects of coupling to a vibrational bath. We capture the effect of slow vibrations by introducing time-dependent disorder. Our model describes the experimentally observed high efficiency of light harvesting, despite the absence of long-range quantum coherence. The one-exciton part of the quantum state fluctuates continuously but remains highly mixed at all times. These results suggest a relatively minor role for structure in determining efficiency. We build hypothetical models with randomly arranged chromophores but still observe high efficiency when nearest-neighbor distances are comparable to those in nature. This helps explain the high transport efficiency in organisms with widely differing antenna structures and suggests new design criteria for artificial light-harvesting devices.
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Affiliation(s)
- Susannah Bourne Worster
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , U.K
| | - Clement Stross
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , U.K
- School of Mathematics , University of Bristol , Bristol BS8 1UG , U.K
| | - Felix M W C Vaughan
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , U.K
- School of Mathematics , University of Bristol , Bristol BS8 1UG , U.K
- Bristol Centre for Complexity Sciences , University of Bristol , Bristol BS2 8BB , U.K
| | - Noah Linden
- School of Mathematics , University of Bristol , Bristol BS8 1UG , U.K
| | - Frederick R Manby
- Centre for Computational Chemistry, School of Chemistry , University of Bristol , Bristol BS8 1TS , U.K
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3
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Rathbone HW, Davis JA, Michie KA, Goodchild SC, Robertson NO, Curmi PMG. Coherent phenomena in photosynthetic light harvesting: part two-observations in biological systems. Biophys Rev 2018; 10:1443-1463. [PMID: 30242555 PMCID: PMC6233342 DOI: 10.1007/s12551-018-0456-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 09/06/2018] [Indexed: 10/28/2022] Open
Abstract
Considerable debate surrounds the question of whether or not quantum mechanics plays a significant, non-trivial role in photosynthetic light harvesting. Many have proposed that quantum superpositions and/or quantum transport phenomena may be responsible for the efficiency and robustness of energy transport present in biological systems. The critical experimental observations comprise the observation of coherent oscillations or "quantum beats" via femtosecond laser spectroscopy, which have been observed in many different light harvesting systems. Part Two of this review aims to provide an overview of experimental observations of energy transfer in the most studied light harvesting systems. Length scales, derived from crystallographic studies, are combined with energy and time scales of the beats observed via spectroscopy. A consensus is emerging that most long-lived (hundreds of femtoseconds) coherent phenomena are of vibrational or vibronic origin, where the latter may result in coherent excitation transport within a protein complex. In contrast, energy transport between proteins is likely to be incoherent in nature. The question of whether evolution has selected for these non-trivial quantum phenomena may be an unanswerable question, as dense packings of chromophores will lead to strong coupling and hence non-trivial quantum phenomena. As such, one cannot discern whether evolution has optimised light harvesting systems for high chromophore density or for the ensuing quantum effects as these are inextricably linked and cannot be switched off.
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Affiliation(s)
- Harry W Rathbone
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Jeffery A Davis
- Centre for Quantum and Optical Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia
| | - Katharine A Michie
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Sophia C Goodchild
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Neil O Robertson
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Paul M G Curmi
- School of Physics, The University of New South Wales, Sydney, New South Wales, 2052, Australia.
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4
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Malý P, Gardiner AT, Cogdell RJ, van Grondelle R, Mančal T. Robust light harvesting by a noisy antenna. Phys Chem Chem Phys 2018; 20:4360-4372. [PMID: 29368769 PMCID: PMC5901068 DOI: 10.1039/c7cp06139k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/13/2017] [Indexed: 01/26/2023]
Abstract
Photosynthetic light harvesting can be very efficient in solar energy conversion while taking place in a highly disordered and noisy physiological environment. This efficiency is achieved by the ultrafast speed of the primary photosynthetic processes, which is enabled by a delicate interplay of quantum effects, thermodynamics and environmental noise. The primary processes take place in light-harvesting antennas built from pigments bound to a fluctuating protein scaffold. Here, we employ ultrafast single-molecule spectroscopy to follow fluctuations of the femtosecond energy transfer times in individual LH2 antenna complexes of purple bacteria. By combining single molecule results with ensemble spectroscopy through a unified theoretical description of both, we show how the protein fluctuations alter the excitation energy transfer dynamics. We find that from the thirteen orders of magnitude of possible timescales from picoseconds to minutes, the relevant fluctuations occur predominantly on a biological timescale of seconds, i.e. in the domain of slow protein motion. The measured spectra and dynamics can be explained by the protein modulating pigment excitation energies only. Moreover, we find that the small spread of pigment mean energies allows for excitation delocalization between the coupled pigments to survive. These unique features provide fast energy transport even in the presence of disorder. We conclude that this is the mechanism that enables LH2 to operate as a robust light-harvester, in spite of its intrinsically noisy biological environment.
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Affiliation(s)
- Pavel Malý
- Department of Biophysics , Faculty of Sciences , Vrije Universiteit Amsterdam , De Boeleaan 1081 , 1081HV Amsterdam , The Netherlands .
- Faculty of Mathematics and Physics , Charles University , Ke Karlovu 3 , 121 16 Prague , Czech Republic
| | - Alastair T. Gardiner
- Institute of Molecular , Cellular and Systems Biology , College of Medical , Veterinary and Life Sciences , University of Glasgow , Glasgow G128QQ , UK
| | - Richard J. Cogdell
- Institute of Molecular , Cellular and Systems Biology , College of Medical , Veterinary and Life Sciences , University of Glasgow , Glasgow G128QQ , UK
| | - Rienk van Grondelle
- Department of Biophysics , Faculty of Sciences , Vrije Universiteit Amsterdam , De Boeleaan 1081 , 1081HV Amsterdam , The Netherlands .
| | - Tomáš Mančal
- Faculty of Mathematics and Physics , Charles University , Ke Karlovu 3 , 121 16 Prague , Czech Republic
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5
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Caycedo-Soler F, Schroeder CA, Autenrieth C, Pick A, Ghosh R, Huelga SF, Plenio MB. Quantum Redirection of Antenna Absorption to Photosynthetic Reaction Centers. J Phys Chem Lett 2017; 8:6015-6021. [PMID: 29185757 DOI: 10.1021/acs.jpclett.7b02714] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The early steps of photosynthesis involve the photoexcitation of reaction centers (RCs) and light-harvesting (LH) units. Here, we show that the historically overlooked excitonic delocalization across RC and LH pigments results in a redistribution of absorption amplitudes that benefits the absorption cross section of the optical bands associated with the RC of several species. While we prove that this redistribution is robust to the microscopic details of the dephasing between these units in the purple bacterium Rhodospirillum rubrum, we are able to show that the redistribution witnesses a more fragile, but persistent, coherent population dynamics which directs excitations from the LH toward the RC units under incoherent illumination and physiological conditions. Even though the redirection does not seem to affect importantly the overall efficiency in photosynthesis, stochastic optimization allows us to delineate clear guidelines and develop simple analytic expressions in order to amplify the coherent redirection in artificial nanostructures.
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Affiliation(s)
- Felipe Caycedo-Soler
- Institute of Theoretical Physics and Integrated Quantum Science and Technology IQST, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
| | - Christopher A Schroeder
- Institute of Theoretical Physics and Integrated Quantum Science and Technology IQST, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
- Joint Quantum Institute, Department of Physics, University of Maryland and National Institute of Standards and Technology , College Park, Maryland 20742, United States
| | - Caroline Autenrieth
- Department of Bioenergetics, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart , Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Arne Pick
- Institute of Theoretical Physics and Integrated Quantum Science and Technology IQST, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
| | - Robin Ghosh
- Department of Bioenergetics, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart , Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Susana F Huelga
- Institute of Theoretical Physics and Integrated Quantum Science and Technology IQST, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
| | - Martin B Plenio
- Institute of Theoretical Physics and Integrated Quantum Science and Technology IQST, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
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6
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Eisenberg I, Caycedo-Soler F, Harris D, Yochelis S, Huelga SF, Plenio MB, Adir N, Keren N, Paltiel Y. Regulating the Energy Flow in a Cyanobacterial Light-Harvesting Antenna Complex. J Phys Chem B 2017; 121:1240-1247. [DOI: 10.1021/acs.jpcb.6b10590] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ido Eisenberg
- Applied
Physics Department and The Center for Nano-Science and Nano-Technology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Felipe Caycedo-Soler
- Institute
of Theoretical Physics, Ulm University, Albert Einstein Alle 11, 89069 Ulm, Germany
| | - Dvir Harris
- Schulich
Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Shira Yochelis
- Applied
Physics Department and The Center for Nano-Science and Nano-Technology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Susana F. Huelga
- Institute
of Theoretical Physics, Ulm University, Albert Einstein Alle 11, 89069 Ulm, Germany
| | - Martin B. Plenio
- Institute
of Theoretical Physics, Ulm University, Albert Einstein Alle 11, 89069 Ulm, Germany
| | - Noam Adir
- Schulich
Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Nir Keren
- Department
of Plant and Environmental Sciences, Alexander Silberman Institute
of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 9190401, Israel
| | - Yossi Paltiel
- Applied
Physics Department and The Center for Nano-Science and Nano-Technology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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7
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Dahlberg PD, Ting PC, Massey SC, Martin EC, Hunter CN, Engel GS. Electronic Structure and Dynamics of Higher-Lying Excited States in Light Harvesting Complex 1 from Rhodobacter sphaeroides. J Phys Chem A 2016; 120:4124-30. [PMID: 27232937 PMCID: PMC5668141 DOI: 10.1021/acs.jpca.6b04146] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Light harvesting in photosynthetic organisms involves efficient transfer of energy from peripheral antenna complexes to core antenna complexes, and ultimately to the reaction center where charge separation drives downstream photosynthetic processes. Antenna complexes contain many strongly coupled chromophores, which complicates analysis of their electronic structure. Two-dimensional electronic spectroscopy (2DES) provides information on energetic coupling and ultrafast energy transfer dynamics, making the technique well suited for the study of photosynthetic antennae. Here, we present 2DES results on excited state properties and dynamics of a core antenna complex, light harvesting complex 1 (LH1), embedded in the photosynthetic membrane of Rhodobacter sphaeroides. The experiment reveals weakly allowed higher-lying excited states in LH1 at 770 nm, which transfer energy to the strongly allowed states at 875 nm with a lifetime of 40 fs. The presence of higher-lying excited states is in agreement with effective Hamiltonians constructed using parameters from crystal structures and atomic force microscopy (AFM) studies. The energy transfer dynamics between the higher- and lower-lying excited states agree with Redfield theory calculations.
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Affiliation(s)
- Peter D. Dahlberg
- Graduate Program in the Biophysical Sciences, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago, Chicago, IL 60637
| | - Po-Chieh Ting
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago, Chicago, IL 60637
| | - Sara C. Massey
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago, Chicago, IL 60637
| | - Elizabeth C. Martin
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - C. Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Gregory S. Engel
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago, Chicago, IL 60637
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8
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Ma F, Yu LJ, Wang-Otomo ZY, van Grondelle R. Temperature dependent LH1 → RC energy transfer in purple bacteria Tch. tepidum with shiftable LH1-Q y band: A natural system to investigate thermally activated energy transfer in photosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:408-14. [DOI: 10.1016/j.bbabio.2015.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 11/16/2015] [Accepted: 12/14/2015] [Indexed: 10/22/2022]
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9
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Lüer L, Carey AM, Henry S, Maiuri M, Hacking K, Polli D, Cerullo G, Cogdell RJ. Elementary Energy Transfer Pathways in Allochromatium vinosum Photosynthetic Membranes. Biophys J 2015; 109:1885-98. [PMID: 26536265 DOI: 10.1016/j.bpj.2015.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/16/2015] [Accepted: 09/08/2015] [Indexed: 11/24/2022] Open
Abstract
Allochromatium vinosum (formerly Chromatium vinosum) purple bacteria are known to adapt their light-harvesting strategy during growth according to environmental factors such as temperature and average light intensity. Under low light illumination or low ambient temperature conditions, most of the LH2 complexes in the photosynthetic membranes form a B820 exciton with reduced spectral overlap with LH1. To elucidate the reason for this light and temperature adaptation of the LH2 electronic structure, we performed broadband femtosecond transient absorption spectroscopy as a function of excitation wavelength in A. vinosum membranes. A target analysis of the acquired data yielded individual rate constants for all relevant elementary energy transfer (ET) processes. We found that the ET dynamics in high-light-grown membranes was well described by a homogeneous model, with forward and backward rate constants independent of the pump wavelength. Thus, the overall B800→B850→B890→ Reaction Center ET cascade is well described by simple triexponential kinetics. In the low-light-grown membranes, we found that the elementary backward transfer rate constant from B890 to B820 was strongly reduced compared with the corresponding constant from B890 to B850 in high-light-grown samples. The ET dynamics of low-light-grown membranes was strongly dependent on the pump wavelength, clearly showing that the excitation memory is not lost throughout the exciton lifetime. The observed pump energy dependence of the forward and backward ET rate constants suggests exciton diffusion via B850→ B850 transfer steps, making the overall ET dynamics nonexponential. Our results show that disorder plays a crucial role in our understanding of low-light adaptation in A. vinosum.
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Affiliation(s)
- Larry Lüer
- Madrid Institute for Advanced Studies, IMDEA Nanociencia, Madrid, Spain.
| | - Anne-Marie Carey
- Glasgow Biomedical Research Centre, IBLS, University of Glasgow, Glasgow, Scotland; Biodesign Institute, Arizona State University, Tempe, Arizona
| | - Sarah Henry
- Glasgow Biomedical Research Centre, IBLS, University of Glasgow, Glasgow, Scotland; Biodesign Institute, Arizona State University, Tempe, Arizona
| | - Margherita Maiuri
- CNR-IFN, Dipartimento di Fisica, Politecnico di Milano, Milano, Italy; Department of Chemistry, Princeton University, Princeton, New Jersey
| | - Kirsty Hacking
- Glasgow Biomedical Research Centre, IBLS, University of Glasgow, Glasgow, Scotland
| | - Dario Polli
- CNR-IFN, Dipartimento di Fisica, Politecnico di Milano, Milano, Italy
| | - Giulio Cerullo
- CNR-IFN, Dipartimento di Fisica, Politecnico di Milano, Milano, Italy
| | - Richard J Cogdell
- Glasgow Biomedical Research Centre, IBLS, University of Glasgow, Glasgow, Scotland
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Abstract
Oxygenic photosynthesis is the principal converter of sunlight into chemical energy on Earth. Cyanobacteria and plants provide the oxygen, food, fuel, fibers, and platform chemicals for life on Earth. The conversion of solar energy into chemical energy is catalyzed by two multisubunit membrane protein complexes, photosystem I (PSI) and photosystem II (PSII). Light is absorbed by the pigment cofactors, and excitation energy is transferred among the antennae pigments and converted into chemical energy at very high efficiency. Oxygenic photosynthesis has existed for more than three billion years, during which its molecular machinery was perfected to minimize wasteful reactions. Light excitation transfer and singlet trapping won over fluorescence, radiation-less decay, and triplet formation. Photosynthetic reaction centers operate in organisms ranging from bacteria to higher plants. They are all evolutionarily linked. The crystal structure determination of photosynthetic protein complexes sheds light on the various partial reactions and explains how they are protected against wasteful pathways and why their function is robust. This review discusses the efficiency of photosynthetic solar energy conversion.
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Affiliation(s)
- Nathan Nelson
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel;
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11
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Harris MA, Sahin T, Jiang J, Vairaprakash P, Parkes-Loach PS, Niedzwiedzki DM, Kirmaier C, Loach PA, Bocian DF, Holten D, Lindsey JS. Enhanced Light-Harvesting Capacity by Micellar Assembly of Free Accessory Chromophores and LH1-like Antennas. Photochem Photobiol 2014; 90:1264-76. [DOI: 10.1111/php.12319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 07/11/2014] [Indexed: 01/05/2023]
Affiliation(s)
| | - Tuba Sahin
- Department of Chemistry; North Carolina State University; Raleigh NC
| | - Jianbing Jiang
- Department of Chemistry; North Carolina State University; Raleigh NC
| | | | | | | | | | - Paul A. Loach
- Department of Molecular Biosciences; Northwestern University; Evanston IL
| | - David F. Bocian
- Department of Chemistry; University of California; Riverside CA
| | - Dewey Holten
- Department of Chemistry; Washington University; St. Louis MO
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