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Zhong K, Nguyen HL, Do TN, Tan HS, Knoester J, Jansen TLC. Coarse-Grained Approach to Simulate Signatures of Excitation Energy Transfer in Two-Dimensional Electronic Spectroscopy of Large Molecular Systems. J Chem Theory Comput 2024; 20:6111-6124. [PMID: 38996082 PMCID: PMC11270824 DOI: 10.1021/acs.jctc.4c00413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 06/25/2024] [Accepted: 06/27/2024] [Indexed: 07/14/2024]
Abstract
Two-dimensional electronic spectroscopy (2DES) has proven to be a highly effective technique in studying the properties of excited states and the process of excitation energy transfer in complex molecular assemblies, particularly in biological light-harvesting systems. However, the accurate simulation of 2DES for large systems still poses a challenge because of the heavy computational demands it entails. In an effort to overcome this limitation, we devised a coarse-grained 2DES method. This method encompasses the treatment of the entire system by dividing it into distinct weakly coupled segments, which are assumed to communicate predominantly through incoherent exciton transfer. We first demonstrate the efficiency of this method through simulation on a model dimer system, which demonstrates a marked improvement in calculation efficiency, with results that exhibit good concordance with reference spectra calculated with less approximate methods. Additionally, the application of this method to the light-harvesting antenna 2 (LH2) complex of purple bacteria showcases its advantages, accuracy, and limitations. Furthermore, simulating the anisotropy decay in LH2 induced by energy transfer and its comparison with experiments confirm that the method is capable of accurately describing dynamical processes in a biologically relevant system. This method presented lends itself to an extension that accounts for the effect of intrasegment relaxation processes on the 2DES spectra, which for computational efficiency are ignored in the implementation reported here. It is envisioned that the method will be employed in the future to accurately and efficiently calculate 2D spectra of more extensive systems, such as photosynthetic supercomplexes.
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Affiliation(s)
- Kai Zhong
- Zernike
Institute for Advanced Materials, University
of Groningen, Nijenborgh 3, 9747 AG Groningen, The Netherlands
- School
of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Hoang Long Nguyen
- Zernike
Institute for Advanced Materials, University
of Groningen, Nijenborgh 3, 9747 AG Groningen, The Netherlands
- School
of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Thanh Nhut Do
- School
of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Howe-Siang Tan
- School
of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Jasper Knoester
- Zernike
Institute for Advanced Materials, University
of Groningen, Nijenborgh 3, 9747 AG Groningen, The Netherlands
- Faculty
of Science, Leiden University, Einsteinweg 55, 2300 RA Leiden, The Netherlands
| | - Thomas L. C. Jansen
- Zernike
Institute for Advanced Materials, University
of Groningen, Nijenborgh 3, 9747 AG Groningen, The Netherlands
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2
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Elvers I, Nguyen-Phan TC, Gardiner AT, Hunter CN, Cogdell RJ, Köhler J. Phasor Analysis Reveals Multicomponent Fluorescence Kinetics in the LH2 Complex from Marichromatium purpuratum. J Phys Chem B 2022; 126:10335-10346. [PMID: 36449272 DOI: 10.1021/acs.jpcb.2c04983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
We investigated the fluorescence kinetics of LH2 complexes from Marichromatium purpuratum, the cryo-EM structure of which has been recently elucidated with 2.4 Å resolution. The experiments have been carried out as a function of the excitation density by varying both the excitation fluence and the repetition rate of the laser excitation. Instead of the usual multiexponential fitting procedure, we applied the less common phasor formalism for evaluating the transients because this allows for a model-free analysis of the data without a priori knowledge about the number of processes that contribute to a particular decay. For the various excitation conditions, this analysis reproduces consistently three lifetime components with decay times below 100 ps, 500 ps, and 730 ps, which were associated with the quenched state, singlet-triplet annihilation, and fluorescence decay, respectively. Moreover, it reveals that the number of decay components that contribute to the transients depends on whether the excitation wavelength is in resonance with the B800 BChl a molecules or with the carotenoids. Based on the mutual arrangement of the chromophores in their binding pockets, this leads us to conclude that the energy transfer pathways within the LH2 complex of this species differ significantly from each other for exciting either the B800 BChl molecules or the carotenoids. Finally, we speculate whether the illumination with strong laser light converts the LH2 complexes studied here into a quenched conformation that might be related to the development of the non-photochemical quenching mechanism that occurs in higher plants.
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Affiliation(s)
- Inga Elvers
- Spectroscopy of Soft Matter, University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
| | - Tu C Nguyen-Phan
- School of Infection and Immunity, Glasgow University, Glasgow G12 8TA, U.K
| | - Alastair T Gardiner
- Laboratory of Anoxygenic Phototrophs, Institute of Microbiology, Czech Academy of Sciences, 379 81 Třeboň, Czech Republic
| | - C Neil Hunter
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - Richard J Cogdell
- School of Molecular Biosciences, Glasgow University, Glasgow G12 8QQ, U.K
| | - Jürgen Köhler
- Spectroscopy of Soft Matter, University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany.,Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany.,Bavarian Polymer Institute, University of Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany
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3
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Dimitriev OP. Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems. Chem Rev 2022; 122:8487-8593. [PMID: 35298145 DOI: 10.1021/acs.chemrev.1c00648] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The exciton, an excited electron-hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay. The goal of this review is to give a systematic and comprehensive view on exciton behavior in π-conjugated molecules and molecular assemblies at all phases of exciton evolution with emphasis on rates typical for this dynamic picture and various consequences of the above dynamics. To uncover the rich variety of exciton behavior, details of exciton formation, exciton transport, exciton energy conversion, direct and reverse intersystem crossing, and radiative and nonradiative decay are considered in different systems, where these processes lead to or are influenced by static and dynamic disorder, charge distribution symmetry breaking, photoinduced reactions, electron and proton transfer, structural rearrangements, exciton coupling with vibrations and intermediate particles, and exciton dissociation and annihilation as well.
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Affiliation(s)
- Oleg P Dimitriev
- V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, pr. Nauki 41, Kyiv 03028, Ukraine
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4
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Shi J, Camacho R, Scheblykin IG. Energy transfer in multi-funnel systems quantitatively assessed by two-dimensional polarization imaging and single funnel approximation: From single molecules to ensembles. J Chem Phys 2022; 156:074108. [DOI: 10.1063/5.0075005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Juanzi Shi
- Division of Chemical Physics and Nano Lund, Lund University, P.O. Box 118, Lund 22100, Sweden
| | - Rafael Camacho
- Center for Cellular Imaging, Core Facilities, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ivan G. Scheblykin
- Division of Chemical Physics and Nano Lund, Lund University, P.O. Box 118, Lund 22100, Sweden
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5
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Sutherland GA, Qian P, Hunter CN, Swainsbury DJ, Hitchcock A. Engineering purple bacterial carotenoid biosynthesis to study the roles of carotenoids in light-harvesting complexes. Methods Enzymol 2022; 674:137-184. [DOI: 10.1016/bs.mie.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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6
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Qian P, Swainsbury DJK, Croll TI, Castro-Hartmann P, Divitini G, Sader K, Hunter CN. Cryo-EM Structure of the Rhodobacter sphaeroides Light-Harvesting 2 Complex at 2.1 Å. Biochemistry 2021; 60:3302-3314. [PMID: 34699186 PMCID: PMC8775250 DOI: 10.1021/acs.biochem.1c00576] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Light-harvesting 2 (LH2) antenna
complexes augment the collection
of solar energy in many phototrophic bacteria. Despite its frequent
role as a model for such complexes, there has been no three-dimensional
(3D) structure available for the LH2 from the purple phototroph Rhodobacter sphaeroides. We used cryo-electron microscopy
(cryo-EM) to determine the 2.1 Å resolution structure of this
LH2 antenna, which is a cylindrical assembly of nine αβ
heterodimer subunits, each of which binds three bacteriochlorophyll a (BChl) molecules and one carotenoid. The high resolution
of this structure reveals all of the interpigment and pigment–protein
interactions that promote the assembly and energy-transfer properties
of this complex. Near the cytoplasmic face of the complex there is
a ring of nine BChls, which absorb maximally at 800 nm and are designated
as B800; each B800 is coordinated by the N-terminal carboxymethionine
of LH2-α, part of a network of interactions with nearby residues
on both LH2-α and LH2-β and with the carotenoid. Nine
carotenoids, which are spheroidene in the strain we analyzed, snake
through the complex, traversing the membrane and interacting with
a ring of 18 BChls situated toward the periplasmic side of the complex.
Hydrogen bonds with C-terminal aromatic residues modify the absorption
of these pigments, which are red-shifted to 850 nm. Overlaps between
the macrocycles of the B850 BChls ensure rapid transfer of excitation
energy around this ring of pigments, which act as the donors of energy
to neighboring LH2 and reaction center light-harvesting 1 (RC–LH1)
complexes.
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Affiliation(s)
- Pu Qian
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, Netherlands.,Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
| | - David J K Swainsbury
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
| | - Tristan I Croll
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, U.K
| | - Pablo Castro-Hartmann
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, Netherlands
| | - Giorgio Divitini
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, U.K
| | - Kasim Sader
- Materials and Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, Netherlands
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
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7
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Saga Y, Otsuka Y, Tanaka A, Masaoka Y, Hidaka T, Nagasawa Y. Energy Transfer Dynamics in Light-Harvesting Complex 2 Variants Containing Oxidized B800 Bacteriochlorophyll a. J Phys Chem B 2021; 125:6830-6836. [PMID: 34139847 DOI: 10.1021/acs.jpcb.1c01592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Excitation energy transfer (EET) in light-harvesting proteins is vital for photosynthetic activities. The pigment compositions and their organizations in these proteins are responsible for the EET functions. Thus, changing the pigment compositions in light-harvesting proteins contributes to a better understanding of EET mechanisms. In this study, we investigated the EET dynamics of two light-harvesting complex 2 (LH2) variants, in which nine B800 bacteriochlorophyll (BChl) a pigments were entirely or half converted to 3-acetyl chlorophyll (AcChl) a. The AcChl a pigments showed a Qy band, which was blue-shifted by 107 nm from B800 BChl a in the two variants. EET from AcChl a to B850 BChl a was observed in both fully oxidized and half-oxidized LH2 variants, but the EET rates were lower than that from B800 to B850 BChl a. EET from AcChl a to the co-present B800 was barely detected in the half-oxidized LH2. The preferential EET from AcChl a to B850 instead of B800 was rationalized by little spectral overlap of AcChl a with B800 BChl a and the pigment geometry in the protein. The EET rate from B800 to B850 BChl a in the half-oxidized LH2 was analogous to that in native LH2, indicating that partial oxidation of B800 did not disturb the EET channel from the residual B800 to B850.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yuji Otsuka
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Aiko Tanaka
- 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
| | - Yutaka Nagasawa
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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8
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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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9
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Femtosecond visible transient absorption spectroscopy of chlorophyll- f-containing photosystem II. Proc Natl Acad Sci U S A 2020; 117:23158-23164. [PMID: 32868421 DOI: 10.1073/pnas.2006016117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The recently discovered, chlorophyll-f-containing, far-red photosystem II (FR-PSII) supports far-red light photosynthesis. Participation and kinetics of spectrally shifted far-red pigments are directly observable and separated from that of bulk chlorophyll-a We present an ultrafast transient absorption study of FR-PSII, investigating energy transfer and charge separation processes. Results show a rapid subpicosecond energy transfer from chlorophyll-a to the long-wavelength chlorophylls-f/d The data demonstrate the decay of an ∼720-nm negative feature on the picosecond-to-nanosecond timescales, coinciding with charge separation, secondary electron transfer, and stimulated emission decay. An ∼675-nm bleach attributed to the loss of chl-a absorption due to the formation of a cation radical, PD1 +•, is only fully developed in the nanosecond spectra, indicating an unusually delayed formation. A major spectral feature on the nanosecond timescale at 725 nm is attributed to an electrochromic blue shift of a FR-chlorophyll among the reaction center pigments. These time-resolved observations provide direct experimental support for the model of Nürnberg et al. [D. J. Nürnberg et al., Science 360, 1210-1213 (2018)], in which the primary electron donor is a FR-chlorophyll and the secondary donor is chlorophyll-a (PD1 of the central chlorophyll pair). Efficient charge separation also occurs using selective excitation of long-wavelength chlorophylls-f/d, and the localization of the excited state on P720* points to a smaller (entropic) energy loss compared to conventional PSII, where the excited state is shared over all of the chlorin pigments. This has important repercussions on understanding the overall energetics of excitation energy transfer and charge separation reactions in FR-PSII.
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10
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Maragani R, Thomas MB, Misra R, D’Souza F. C3-Symmetric Positional Isomers of BODIPY Substituted Triazines: Synthesis and Excited State Properties. J Phys Chem A 2018; 122:4829-4837. [DOI: 10.1021/acs.jpca.8b02967] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ramesh Maragani
- Department of Chemistry, Indian Institute of Technology, Indore 453552, India
| | - Michael B. Thomas
- Department of Chemistry, University of North Texas, 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States
| | - Rajneesh Misra
- Department of Chemistry, Indian Institute of Technology, Indore 453552, India
| | - Francis D’Souza
- Department of Chemistry, University of North Texas, 1155 Union Circle, #305070, Denton, Texas 76203-5017, United States
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11
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Ogren JI, Tong AL, Gordon SC, Chenu A, Lu Y, Blankenship RE, Cao J, Schlau-Cohen GS. Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2. Chem Sci 2018; 9:3095-3104. [PMID: 29732092 PMCID: PMC5914429 DOI: 10.1039/c7sc04814a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 02/05/2018] [Indexed: 01/28/2023] Open
Abstract
Photosynthetic purple bacteria convert solar energy to chemical energy with near unity quantum efficiency. The light-harvesting process begins with absorption of solar energy by an antenna protein called Light-Harvesting Complex 2 (LH2). Energy is subsequently transferred within LH2 and then through a network of additional light-harvesting proteins to a central location, termed the reaction center, where charge separation occurs. The energy transfer dynamics of LH2 are highly sensitive to intermolecular distances and relative organizations. As a result, minor structural perturbations can cause significant changes in these dynamics. Previous experiments have primarily been performed in two ways. One uses non-native samples where LH2 is solubilized in detergent, which can alter protein structure. The other uses complex membranes that contain multiple proteins within a large lipid area, which make it difficult to identify and distinguish perturbations caused by protein-protein interactions and lipid-protein interactions. Here, we introduce the use of the biochemical platform of model membrane discs to study the energy transfer dynamics of photosynthetic light-harvesting complexes in a near-native environment. We incorporate a single LH2 from Rhodobacter sphaeroides into membrane discs that provide a spectroscopically amenable sample in an environment more physiological than detergent but less complex than traditional membranes. This provides a simplified system to understand an individual protein and how the lipid-protein interaction affects energy transfer dynamics. We compare the energy transfer rates of detergent-solubilized LH2 with those of LH2 in membrane discs using transient absorption spectroscopy and transient absorption anisotropy. For one key energy transfer step in LH2, we observe a 30% enhancement of the rate for LH2 in membrane discs compared to that in detergent. Based on experimental results and theoretical modeling, we attribute this difference to tilting of the peripheral bacteriochlorophyll in the B800 band. These results highlight the importance of well-defined systems with near-native membrane conditions for physiologically-relevant measurements.
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Affiliation(s)
- John I Ogren
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Ashley L Tong
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Samuel C Gordon
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Aurélia Chenu
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Yue Lu
- Department of Biology and Chemistry , Washington University in St. Louis , St. Louis , MO 63130 , USA
| | - Robert E Blankenship
- Department of Biology and Chemistry , Washington University in St. Louis , St. Louis , MO 63130 , USA
| | - Jianshu Cao
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
| | - Gabriela S Schlau-Cohen
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , MA 02139 , USA .
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12
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Thyrhaug E, Lincoln CN, Branchi F, Cerullo G, Perlík V, Šanda F, Lokstein H, Hauer J. Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum. PHOTOSYNTHESIS RESEARCH 2018; 135:45-54. [PMID: 28523607 PMCID: PMC5783993 DOI: 10.1007/s11120-017-0398-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/09/2017] [Indexed: 06/07/2023]
Abstract
The peripheral light-harvesting antenna complex (LH2) of purple photosynthetic bacteria is an ideal testing ground for models of structure-function relationships due to its well-determined molecular structure and ultrafast energy deactivation. It has been the target for numerous studies in both theory and ultrafast spectroscopy; nevertheless, certain aspects of the convoluted relaxation network of LH2 lack a satisfactory explanation by conventional theories. For example, the initial carotenoid-to-bacteriochlorophyll energy transfer step necessary on visible light excitation was long considered to follow the Förster mechanism, even though transfer times as short as 40 femtoseconds (fs) have been observed. Such transfer times are hard to accommodate by Förster theory, as the moderate coupling strengths found in LH2 suggest much slower transfer within this framework. In this study, we investigate LH2 from Phaeospirillum (Ph.) molischianum in two types of transient absorption experiments-with narrowband pump and white-light probe resulting in 100 fs time resolution, and with degenerate broadband 10 fs pump and probe pulses. With regard to the split Qx band in this system, we show that vibronically mediated transfer explains both the ultrafast carotenoid-to-B850 transfer, and the almost complete lack of transfer to B800. These results are beyond Förster theory, which predicts an almost equal partition between the two channels.
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Affiliation(s)
- Erling Thyrhaug
- Photonics Institute, TU Wien, Gußhausstraße 27, 1040, Vienna, Austria
| | - Craig N Lincoln
- Photonics Institute, TU Wien, Gußhausstraße 27, 1040, Vienna, Austria
| | - Federico Branchi
- Dipartimento di Fisica, IFN-CNR, Politecnico di Milano, Piazza L. da Vinci, 32, 20133, Milan, Italy
| | - Giulio Cerullo
- Dipartimento di Fisica, IFN-CNR, Politecnico di Milano, Piazza L. da Vinci, 32, 20133, Milan, Italy
| | - Václav Perlík
- Faculty of Mathematics and Physics, Institute of Physics, Charles University, Ke Karlovu 5, 12116, Prague, Czech Republic
| | - František Šanda
- Faculty of Mathematics and Physics, Institute of Physics, Charles University, Ke Karlovu 5, 12116, Prague, Czech Republic
| | - Heiko Lokstein
- Department of Chemical Physics and Optics, Charles University, Ke Karlovu 3, 12116, Praha 2, Czech Republic
| | - Jürgen Hauer
- Photonics Institute, TU Wien, Gußhausstraße 27, 1040, Vienna, Austria.
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13
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Dachev M, Bína D, Sobotka R, Moravcová L, Gardian Z, Kaftan D, Šlouf V, Fuciman M, Polívka T, Koblížek M. Unique double concentric ring organization of light harvesting complexes in Gemmatimonas phototrophica. PLoS Biol 2017; 15:e2003943. [PMID: 29253871 PMCID: PMC5749889 DOI: 10.1371/journal.pbio.2003943] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 01/02/2018] [Accepted: 11/22/2017] [Indexed: 11/29/2022] Open
Abstract
The majority of life on Earth depends directly or indirectly on the sun as a source of energy. The initial step of photosynthesis is facilitated by light-harvesting complexes, which capture and transfer light energy into the reaction centers (RCs). Here, we analyzed the organization of photosynthetic (PS) complexes in the bacterium G. phototrophica, which so far is the only phototrophic representative of the bacterial phylum Gemmatimonadetes. The isolated complex has a molecular weight of about 800 ± 100 kDa, which is approximately 2 times larger than the core complex of Rhodospirillum rubrum. The complex contains 62.4 ± 4.7 bacteriochlorophyll (BChl) a molecules absorbing in 2 distinct infrared absorption bands with maxima at 816 and 868 nm. Using femtosecond transient absorption spectroscopy, we determined the energy transfer time between these spectral bands as 2 ps. Single particle analyses of the purified complexes showed that they were circular structures with an outer diameter of approximately 18 nm and a thickness of 7 nm. Based on the obtained, we propose that the light-harvesting complexes in G. phototrophica form 2 concentric rings surrounding the type 2 RC. The inner ring (corresponding to the B868 absorption band) is composed of 15 subunits and is analogous to the inner light-harvesting complex 1 (LH1) in purple bacteria. The outer ring is composed of 15 more distant BChl dimers with no or slow energy transfer between them, resulting in the B816 absorption band. This completely unique and elegant organization offers good structural stability, as well as high efficiency of light harvesting. Our results reveal that while the PS apparatus of Gemmatimonadetes was acquired via horizontal gene transfer from purple bacteria, it later evolved along its own pathway, devising a new arrangement of its light harvesting complexes. The majority of life on Earth depends directly or indirectly on the sun as a source of energy. Phototrophic organisms use energy from light to power various cellular and metabolic processes. The initial step of photosynthesis is facilitated by light-harvesting complexes, which capture and transfer light energy into the reaction centers where it is used to power proton gradients or to form new chemical bonds. Here, we analyzed photosynthetic complexes in Gemmatimonas phototrophica, the only known phototrophic representative of the bacterial phylum Gemmatimonadetes. Using a combination of biochemical and spectroscopic techniques, we show that the light-harvesting complexes of G. phototrophica are organized in 2 concentric rings around the reaction center. This organization is unique among anoxygenic phototrophs. It offers both structural stability and high efficiency of light harvesting. The structural unit of both antenna rings is a dimer of photosynthetic pigments called bacteriochlorophyll. The inner ring is populated by more densely packed dimers, while the outer ring contains more distant dimers with a minimal excitation exchange. Such an arrangement modifies the spectral properties of bacteriochlorophylls in the complex and ensures efficient capture of light in the near-infrared part of the solar spectrum.
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Affiliation(s)
- Marko Dachev
- Center Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
| | - David Bína
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Biology Center of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Roman Sobotka
- Center Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Lenka Moravcová
- Center Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
| | - Zdenko Gardian
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Biology Center of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - David Kaftan
- Center Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Václav Šlouf
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Marcel Fuciman
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Tomáš Polívka
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Biology Center of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Michal Koblížek
- Center Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- * E-mail:
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14
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Light harvesting in phototrophic bacteria: structure and function. Biochem J 2017; 474:2107-2131. [DOI: 10.1042/bcj20160753] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 12/23/2022]
Abstract
This review serves as an introduction to the variety of light-harvesting (LH) structures present in phototrophic prokaryotes. It provides an overview of the LH complexes of purple bacteria, green sulfur bacteria (GSB), acidobacteria, filamentous anoxygenic phototrophs (FAP), and cyanobacteria. Bacteria have adapted their LH systems for efficient operation under a multitude of different habitats and light qualities, performing both oxygenic (oxygen-evolving) and anoxygenic (non-oxygen-evolving) photosynthesis. For each LH system, emphasis is placed on the overall architecture of the pigment–protein complex, as well as any relevant information on energy transfer rates and pathways. This review addresses also some of the more recent findings in the field, such as the structure of the CsmA chlorosome baseplate and the whole-cell kinetics of energy transfer in GSB, while also pointing out some areas in need of further investigation.
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15
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Chenchiliyan M, Timpmann K, Jalviste E, Adams PG, Hunter CN, Freiberg A. Dimerization of core complexes as an efficient strategy for energy trapping in Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:634-42. [DOI: 10.1016/j.bbabio.2016.03.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/16/2016] [Accepted: 03/18/2016] [Indexed: 11/24/2022]
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16
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Baghbanzadeh S, Kassal I. Distinguishing the roles of energy funnelling and delocalization in photosynthetic light harvesting. Phys Chem Chem Phys 2016; 18:7459-67. [PMID: 26899714 DOI: 10.1039/c6cp00104a] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Photosynthetic complexes improve the transfer of excitation energy from peripheral antennas to reaction centers in several ways. In particular, a downward energy funnel can direct excitons in the right direction, while coherent excitonic delocalization can enhance transfer rates through the cooperative phenomenon of supertransfer. However, isolating the role of purely coherent effects is difficult because any change to the delocalization also changes the energy landscape. Here, we show that the relative importance of the two processes can be determined by comparing the natural light-harvesting apparatus with counterfactual models in which the delocalization and the energy landscape are altered. Applied to the example of purple bacteria, our approach shows that although supertransfer does enhance the rates somewhat, the energetic funnelling plays the decisive role. Because delocalization has a minor role (and is sometimes detrimental), it is most likely not adaptive, being a side-effect of the dense chlorophyll packing that evolved to increase light absorption per reaction center.
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Affiliation(s)
- Sima Baghbanzadeh
- Department of Physics, Sharif University of Technology, Tehran, Iran and Centre for Engineered Quantum Systems, Centre for Quantum Computation and Communication Technology, and School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072, Australia.
| | - Ivan Kassal
- Centre for Engineered Quantum Systems, Centre for Quantum Computation and Communication Technology, and School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072, Australia.
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17
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Anda A, Hansen T, De Vico L. Multireference Excitation Energies for Bacteriochlorophylls A within Light Harvesting System 2. J Chem Theory Comput 2016; 12:1305-13. [DOI: 10.1021/acs.jctc.5b01104] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- André Anda
- Department of Chemistry, Copenhagen University, Universitetsparken 5, DK-2100, Copenhagen Ø, Denmark
| | - Thorsten Hansen
- Department of Chemistry, Copenhagen University, Universitetsparken 5, DK-2100, Copenhagen Ø, Denmark
| | - Luca De Vico
- Department of Chemistry, Copenhagen University, Universitetsparken 5, DK-2100, Copenhagen Ø, Denmark
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18
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Shi Y, Zhao NJ, Wang P, Fu LM, Yu LJ, Zhang JP, Wang-Otomo ZY. Thermal Adaptability of the Light-Harvesting Complex 2 from Thermochromatium tepidum: Temperature-Dependent Excitation Transfer Dynamics. J Phys Chem B 2015; 119:14871-9. [DOI: 10.1021/acs.jpcb.5b09023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ying Shi
- Department
of Chemistry, Renmin University of China, Beijing 1000872, P. R. China
| | - Ning-Jiu Zhao
- Department
of Chemistry, Renmin University of China, Beijing 1000872, P. R. China
| | - Peng Wang
- Department
of Chemistry, Renmin University of China, Beijing 1000872, P. R. China
| | - Li-Min Fu
- Department
of Chemistry, Renmin University of China, Beijing 1000872, P. R. China
| | - Long-Jiang Yu
- Faculty
of Science, Ibaraki University, Mito 310-8512, Japan
| | - Jian-Ping Zhang
- Department
of Chemistry, Renmin University of China, Beijing 1000872, P. R. China
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19
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Camacho R, Tubasum S, Southall J, Cogdell RJ, Sforazzini G, Anderson HL, Pullerits T, Scheblykin IG. Fluorescence polarization measures energy funneling in single light-harvesting antennas--LH2 vs conjugated polymers. Sci Rep 2015; 5:15080. [PMID: 26478272 PMCID: PMC4609963 DOI: 10.1038/srep15080] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 09/09/2015] [Indexed: 01/15/2023] Open
Abstract
Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.
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Affiliation(s)
- Rafael Camacho
- Chemical Physics, Lund University, PO Box 124, Lund, SE-22100, Sweden
| | - Sumera Tubasum
- Chemical Physics, Lund University, PO Box 124, Lund, SE-22100, Sweden
| | - June Southall
- Glasgow Biomedical Research Centre, University of Glasgow, G12 8QQ, United Kingdom
| | - Richard J Cogdell
- Glasgow Biomedical Research Centre, University of Glasgow, G12 8QQ, United Kingdom
| | - Giuseppe Sforazzini
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Harry L Anderson
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, United Kingdom
| | - Tõnu Pullerits
- Chemical Physics, Lund University, PO Box 124, Lund, SE-22100, Sweden
| | - Ivan G Scheblykin
- Chemical Physics, Lund University, PO Box 124, Lund, SE-22100, Sweden
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20
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Rätsep M, Pajusalu M, Linnanto JM, Freiberg A. Subtle spectral effects accompanying the assembly of bacteriochlorophylls into cyclic light harvesting complexes revealed by high-resolution fluorescence spectroscopy. J Chem Phys 2015; 141:155102. [PMID: 25338912 DOI: 10.1063/1.4897637] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have observed that an assembly of the bacteriochloropyll a molecules into B850 and B875 groups of cyclic bacterial light-harvesting complexes LH2 and LH1, respectively, results an almost total loss of the intra-molecular vibronic structure in the fluorescence spectrum, and simultaneously, an essential enhancement of its phonon sideband due to electron-phonon coupling. While the suppression of the vibronic coupling in delocalized (excitonic) molecular systems is predictable, as also confirmed by our model calculations, a boost of the electron-phonon coupling is rather unexpected. The latter phenomenon is explained by exciton self-trapping, promoted by mixing the molecular exciton states with charge transfer states between the adjacent chromophores in the tightly packed B850 and B875 arrangements. Similar, although less dramatic trends were noted for the light-harvesting complexes containing chlorophyll pigments.
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Affiliation(s)
- Margus Rätsep
- Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia
| | - Mihkel Pajusalu
- Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia
| | | | - Arvi Freiberg
- Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia and Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
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21
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Schroeder CA, Caycedo-Soler F, Huelga SF, Plenio MB. Optical Signatures of Quantum Delocalization over Extended Domains in Photosynthetic Membranes. J Phys Chem A 2015; 119:9043-50. [PMID: 26256512 DOI: 10.1021/acs.jpca.5b04804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The prospect of coherent dynamics and excitonic delocalization across several light-harvesting structures in photosynthetic membranes is of considerable interest, but challenging to explore experimentally. Here we demonstrate theoretically that the excitonic delocalization across extended domains involving several light-harvesting complexes can lead to unambiguous signatures in the optical response, specifically, linear absorption spectra. We characterize, under experimentally established conditions of molecular assembly and protein-induced inhomogeneities, the optical absorption in these arrays from polarized and unpolarized excitation, and demonstrate that it can be used as a diagnostic tool to determine the resonance coupling between iso-energetic light-harvesting structures. The knowledge of these couplings would then provide further insight into the dynamical properties of transfer, such as facilitating the accurate determination of Förster rates.
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Affiliation(s)
- Christopher A Schroeder
- Institute of Theoretical Physics, 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
| | - Felipe Caycedo-Soler
- Institute of Theoretical Physics, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
| | - Susana F Huelga
- Institute of Theoretical Physics, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
| | - Martin B Plenio
- Institute of Theoretical Physics, University of Ulm , Albert-Einstein-Allee 11, D-89069 Ulm, Germany
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22
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Dewa T, Sumino A, Watanabe N, Noji T, Nango M. Structure–function relationships of the supramolecular assembly of the bacterial photosynthetic antenna complexes in lipid membranes. RESEARCH ON CHEMICAL INTERMEDIATES 2014. [DOI: 10.1007/s11164-014-1830-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Fidler AF, Singh VP, Long PD, Dahlberg PD, Engel GS. Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy. J Chem Phys 2014; 139:155101. [PMID: 24160544 DOI: 10.1063/1.4824637] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.
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Affiliation(s)
- Andrew F Fidler
- Department of Chemistry, The Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
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24
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Hsu CP. Theoretical Study of Photosynthetic Light-Harvesting Processes: Application of Time-Dependent Density Functional Theory. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200300106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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25
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Sumino A, Dewa T, Noji T, Nakano Y, Watanabe N, Hildner R, Bösch N, Köhler J, Nango M. Influence of Phospholipid Composition on Self-Assembly and Energy-Transfer Efficiency in Networks of Light-Harvesting 2 Complexes. J Phys Chem B 2013; 117:10395-404. [DOI: 10.1021/jp4047819] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Ayumi Sumino
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Takehisa Dewa
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Tomoyasu Noji
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Yuki Nakano
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Natsuko Watanabe
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Richard Hildner
- Experimental
Physics IV and BIMF, University of Bayreuth, D-95440 Bayreuth, Germany
| | - Nils Bösch
- Experimental
Physics IV and BIMF, University of Bayreuth, D-95440 Bayreuth, Germany
| | - Jürgen Köhler
- Experimental
Physics IV and BIMF, University of Bayreuth, D-95440 Bayreuth, Germany
| | - Mamoru Nango
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
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26
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Energy transfer and clustering of photosynthetic light-harvesting complexes in reconstituted lipid membranes. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.12.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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27
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Fidler AF, Singh VP, Long PD, Dahlberg PD, Engel GS. Timescales of Coherent Dynamics in the Light Harvesting Complex 2 (LH2) of Rhodobacter sphaeroides. J Phys Chem Lett 2013; 4:1404-1409. [PMID: 23878622 PMCID: PMC3714110 DOI: 10.1021/jz400438m] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The initial dynamics of energy transfer in the light harvesting complex 2 from Rhodobacter sphaeroides were investigated with polarization controlled two-dimensional spectroscopy. This method allows only the coherent electronic motions to be observed revealing the timescale of dephasing among the excited states. We observe persistent coherence among all states and assign ensemble dephasing rates for the various coherences. A simple model is utilized to connect the spectroscopic transitions to the molecular structure, allowing us to distinguish coherences between the two rings of chromophores and coherences within the rings. We also compare dephasing rates between excited states to dephasing rates between the ground and excited states, revealing that the coherences between excited states dephase on a slower timescale than coherences between the ground and excited states.
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Affiliation(s)
- Andrew F. Fidler
- Department of Chemistry, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Ved P. Singh
- Department of Chemistry, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Phillip D. Long
- Program in the Biophysical Sciences, The University of Chicago, Chicago, IL 60637
| | - Peter D. Dahlberg
- Program in the Biophysical Sciences, The University of Chicago, Chicago, IL 60637
| | - Gregory S. Engel
- Department of Chemistry, The James Franck Institute and The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
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28
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Harvey PD, Brégier F, Aly SM, Szmytkowski J, Paige MF, Steer RP. Dendron to Central Core S1-S1and S2-Sn(n>1) Energy Transfers in Artificial Special Pairs Containing Dendrimers with Limited Numbers of Conformations. Chemistry 2013; 19:4352-68. [DOI: 10.1002/chem.201203033] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Indexed: 11/08/2022]
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29
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Stepanenko I, Kompanetz V, Makhneva Z, Chekalin S, Moskalenko A, Razjivin A. Transient Absorption Study of Two-Photon Excitation Mechanism in the LH2 Complex from Purple Bacterium Rhodobacter sphaeroides. J Phys Chem B 2012; 116:2886-90. [DOI: 10.1021/jp2033214] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ilya Stepanenko
- A. N. Belozersky Institute of
Physico-Chemical Biology, Moscow State University, Leninskie Gory, 119992 Moscow, Russia
| | - Viktor Kompanetz
- Institute of Spectroscopy RAS, 142190 Troitsk, Moscow Region, Russia
| | - Zoya Makhneva
- Institute of Fundamental Problems of Biology RAS, 142290 Pushchino, Moscow Region,
Russia
| | - Sergey Chekalin
- Institute of Spectroscopy RAS, 142190 Troitsk, Moscow Region, Russia
| | - Andrei Moskalenko
- Institute of Fundamental Problems of Biology RAS, 142290 Pushchino, Moscow Region,
Russia
| | - Andrei Razjivin
- A. N. Belozersky Institute of
Physico-Chemical Biology, Moscow State University, Leninskie Gory, 119992 Moscow, Russia
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30
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Kloz M, Pillai S, Kodis G, Gust D, Moore TA, Moore AL, Grondelle RV, Kennis JTM. New light-harvesting roles of hot and forbidden carotenoid states in artificial photosynthetic constructs. Chem Sci 2012. [DOI: 10.1039/c2sc01023b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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31
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König C, Neugebauer J. Quantum chemical description of absorption properties and excited-state processes in photosynthetic systems. Chemphyschem 2011; 13:386-425. [PMID: 22287108 DOI: 10.1002/cphc.201100408] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Indexed: 11/07/2022]
Abstract
The theoretical description of the initial steps in photosynthesis has gained increasing importance over the past few years. This is caused by more and more structural data becoming available for light-harvesting complexes and reaction centers which form the basis for atomistic calculations and by the progress made in the development of first-principles methods for excited electronic states of large molecules. In this Review, we discuss the advantages and pitfalls of theoretical methods applicable to photosynthetic pigments. Besides methodological aspects of excited-state electronic-structure methods, studies on chlorophyll-type and carotenoid-like molecules are discussed. We also address the concepts of exciton coupling and excitation-energy transfer (EET) and compare the different theoretical methods for the calculation of EET coupling constants. Applications to photosynthetic light-harvesting complexes and reaction centers based on such models are also analyzed.
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Affiliation(s)
- Carolin König
- Institute for Physical and Theoretical Chemistry, Technical University Braunschweig, Braunschweig, Germany
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32
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Pflock TJ, Oellerich S, Southall J, Cogdell RJ, Ullmann GM, Köhler J. The Electronically Excited States of LH2 Complexes from Rhodopseudomonas acidophila Strain 10050 Studied by Time-Resolved Spectroscopy and Dynamic Monte Carlo Simulations. I. Isolated, Non-Interacting LH2 Complexes. J Phys Chem B 2011; 115:8813-20. [DOI: 10.1021/jp202353c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tobias J. Pflock
- Experimental Physics IV and BIMF, University of Bayreuth, D-95440 Bayreuth, Germany
| | - Silke Oellerich
- Experimental Physics IV and BIMF, University of Bayreuth, D-95440 Bayreuth, Germany
| | - June Southall
- Institute of Molecular, Cell and Systems Biology, College of Medical Veterinary and Life Sciences, Biomedical Research Building, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - Richard J. Cogdell
- Institute of Molecular, Cell and Systems Biology, College of Medical Veterinary and Life Sciences, Biomedical Research Building, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - G. Matthias Ullmann
- Computational Biochemistry/Bioinformatics, University of Bayreuth, D-95440 Bayreuth
| | - Jürgen Köhler
- Experimental Physics IV and BIMF, University of Bayreuth, D-95440 Bayreuth, Germany
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33
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Yang F, Yu LJ, Wang P, Ai XC, Wang ZY, Zhang JP. Effects of Aggregation on the Excitation Dynamics of LH2 from Thermochromatium tepidum in Aqueous Phase and in Chromatophores. J Phys Chem B 2011; 115:7906-13. [DOI: 10.1021/jp1097537] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Fan Yang
- Department of Chemistry, Renmin University of China, Beijing 100872, People's Repulic of China
- College of Electronic Science and Engineering, Jilin University, Changchun 130012, People's Republic of China
| | - Long-Jiang Yu
- Faculty of Science, Ibaraki University, Mito 310-8512, Japan
| | - Peng Wang
- Department of Chemistry, Renmin University of China, Beijing 100872, People's Repulic of China
| | - Xi-Cheng Ai
- Department of Chemistry, Renmin University of China, Beijing 100872, People's Repulic of China
| | - Zheng-Yu Wang
- Faculty of Science, Ibaraki University, Mito 310-8512, Japan
| | - Jian-Ping Zhang
- Department of Chemistry, Renmin University of China, Beijing 100872, People's Repulic of China
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34
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Jankowiak R, Reppert M, Zazubovich V, Pieper J, Reinot T. Site Selective and Single Complex Laser-Based Spectroscopies: A Window on Excited State Electronic Structure, Excitation Energy Transfer, and Electron–Phonon Coupling of Selected Photosynthetic Complexes. Chem Rev 2011; 111:4546-98. [DOI: 10.1021/cr100234j] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ryszard Jankowiak
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
| | - Mike Reppert
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
| | - Valter Zazubovich
- Department of Physics, Concordia University, Montreal H4B1R6 Quebec, Canada
| | - Jörg Pieper
- Max-Volmer-Laboratories for Biophysical Chemistry, Technical University of Berlin, Germany
- Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia
| | - Tonu Reinot
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States
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35
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Cruz AJ, Siam K, Rillema DP. Dicyano and Pyridine Derivatives of β-Carotene: Synthesis and Vibronic, Electronic, and Photophysical Properties. J Phys Chem A 2011; 115:1108-16. [DOI: 10.1021/jp106293s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. J. Cruz
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260, United States
| | - K. Siam
- Department of Chemistry, Pittsburgh State University, Pittsburgh, Kansas 66762, United States
| | - D. P. Rillema
- Department of Chemistry, Wichita State University, Wichita, Kansas 67260, United States
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36
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Polívka T, Frank HA. Molecular factors controlling photosynthetic light harvesting by carotenoids. Acc Chem Res 2010; 43:1125-34. [PMID: 20446691 DOI: 10.1021/ar100030m] [Citation(s) in RCA: 247] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Carotenoids are naturally occurring pigments that absorb light in the spectral region in which the sun irradiates maximally. These molecules transfer this energy to chlorophylls, initiating the primary photochemical events of photosynthesis. Carotenoids also regulate the flow of energy within the photosynthetic apparatus and protect it from photoinduced damage caused by excess light absorption. To carry out these functions in nature, carotenoids are bound in discrete pigment-protein complexes in the proximity of chlorophylls. A few three-dimensional structures of these carotenoid complexes have been determined by X-ray crystallography. Thus, the stage is set for attempting to correlate the structural information with the spectroscopic properties of carotenoids to understand the molecular mechanism(s) of their function in photosynthetic systems. In this Account, we summarize current spectroscopic data describing the excited state energies and ultrafast dynamics of purified carotenoids in solution and bound in light-harvesting complexes from purple bacteria, marine algae, and green plants. Many of these complexes can be modified using mutagenesis or pigment exchange which facilitates the elucidation of correlations between structure and function. We describe the structural and electronic factors controlling the function of carotenoids as energy donors. We also discuss unresolved issues related to the nature of spectroscopically dark excited states, which could play a role in light harvesting. To illustrate the interplay between structural determinations and spectroscopic investigations that exemplifies work in the field, we describe the spectroscopic properties of four light-harvesting complexes whose structures have been determined to atomic resolution. The first, the LH2 complex from the purple bacterium Rhodopseudomonas acidophila, contains the carotenoid rhodopin glucoside. The second is the LHCII trimeric complex from higher plants which uses the carotenoids lutein, neoxanthin, and violaxanthin to transfer energy to chlorophyll. The third, the peridinin-chlorophyll-protein (PCP) from the dinoflagellate Amphidinium carterae, is the only known complex in which the bound carotenoid (peridinin) pigments outnumber the chlorophylls. The last is xanthorhodopsin from the eubacterium Salinibacter ruber. This complex contains the carotenoid salinixanthin, which transfers energy to a retinal chromophore. The carotenoids in these pigment-protein complexes transfer energy with high efficiency by optimizing both the distance and orientation of the carotenoid donor and chlorophyll acceptor molecules. Importantly, the versatility and robustness of carotenoids in these light-harvesting pigment-protein complexes have led to their incorporation in the design and synthesis of nanoscale antenna systems. In these bioinspired systems, researchers are seeking to improve the light capture and use of energy from the solar emission spectrum.
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Affiliation(s)
- Tomáš Polívka
- Institute of Physical Biology, University of South Bohemia, Zámek 136, 373 33 Nové Hrady, Czech Republic
- Biological Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Harry A. Frank
- Department of Chemistry, 55 North Eagleville Road, University of Connecticut, Storrs, Connecticut 06269-3060
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Spectral dependence of energy transfer in wild-type peripheral light-harvesting complexes of photosynthetic bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1465-9. [DOI: 10.1016/j.bbabio.2010.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 04/28/2010] [Accepted: 05/05/2010] [Indexed: 11/20/2022]
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38
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van Grondelle R, Monshouwer R, Valkunas L. Photosynthetic antennae. Photosynthetic light-harvesting. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19961001204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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39
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Martiskainen J, Linnanto J, Kananavičius R, Lehtovuori V, Korppi-Tommola J. Excitation energy transfer in isolated chlorosomes from Chloroflexus aurantiacus. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.06.080] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Brust T, Draxler S, Rauh A, Silber MV, Braun P, Zinth W, Braun M. Mutations of the peripheral antenna complex LH2 – correlations of energy transfer time with other functional properties. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2008.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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41
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Bonetti C, Alexandre M, Hiller R, Kennis J, Grondelle RV. Chl-a triplet quenching by peridinin in H-PCP and organic solvent revealed by step-scan FTIR time-resolved spectroscopy. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2008.10.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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42
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Freiberg A, Trinkunas G. Unraveling the Hidden Nature of Antenna Excitations. PHOTOSYNTHESIS IN SILICO 2009. [DOI: 10.1007/978-1-4020-9237-4_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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43
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Liu K, Liu W, Yan Y, Dong Z, Xu C, Qian S. Excited-state dynamics in light-harvesting complex of Rhodobacter sphaeroides. Sci Bull (Beijing) 2008. [DOI: 10.1007/s11434-008-0187-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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44
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Sugisaki M, Fujii R, Cogdell RJ, Hashimoto H. Linear and nonlinear optical responses in bacteriochlorophyll a. PHOTOSYNTHESIS RESEARCH 2008; 95:309-316. [PMID: 17926140 DOI: 10.1007/s11120-007-9266-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 09/13/2007] [Indexed: 05/25/2023]
Abstract
Nonlinear optical responses of bacteriochlorophyll a (BChl a) were investigated by means of the three-pulse four-wave mixing (FWM) technique under the resonant excitation into the Q ( y ) band. The experimental results are explained by a theoretical model calculation including the Brownian oscillation mode of the solvent. We have determined the spectral density, which is the most important function with which to calculate optical signals. The linear absorption spectrum can be reproduced fairly well when the vibronic oscillation modes of the solvent together with those of BChl a are properly taken into consideration. The FWM signal was also calculated using the spectral density. It was found that a simple two-level model could not explain the experimental result. The effect of the higher-order interactions is discussed.
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Affiliation(s)
- Mitsuru Sugisaki
- Graduate School of Science, Osaka City University, Sugimoto, Sumiyoshi, Osaka, 558-8585, Japan.
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45
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Fujii R, Shimonaka S, Uchida N, Gardiner AT, Cogdell RJ, Sugisaki M, Hashimoto H. Construction of hybrid photosynthetic units using peripheral and core antennae from two different species of photosynthetic bacteria: detection of the energy transfer from bacteriochlorophyll a in LH2 to bacteriochlorophyll b in LH1. PHOTOSYNTHESIS RESEARCH 2008; 95:327-337. [PMID: 17926141 DOI: 10.1007/s11120-007-9260-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 09/10/2007] [Indexed: 05/25/2023]
Abstract
Typical purple bacterial photosynthetic units consist of supra-molecular arrays of peripheral (LH2) and core (LH1-RC) antenna complexes. Recent atomic force microscopy pictures of photosynthetic units in intact membranes have revealed that the architecture of these units is variable (Scheuring et al. (2005) Biochim Bhiophys Acta 1712:109-127). In this study, we describe methods for the construction of heterologous photosynthetic units in lipid-bilayers from mixtures of purified LH2 (from Rhodopseudomonas acidophila) and LH1-RC (from Rhodopseudomonas viridis) core complexes. The architecture of these reconstituted photosynthetic units can be varied by controlling ratio of added LH2 to core complexes. The arrangement of the complexes was visualized by electron-microscopy in combination with Fourier analysis. The regular trigonal array of the core complexes seen in the native photosynthetic membrane could be regenerated in the reconstituted membranes by temperature cycling. In the presence of added LH2 complexes, this trigonal symmetry was replaced with orthorhombic symmetry. The small lattice lengths for the latter suggest that the constituent unit of the orthorhombic lattice is the LH2. Fluorescence and fluorescence-excitation spectroscopy was applied to the set of the reconstituted membranes prepared with various proportions of LH2 to core complexes. Remarkably, even though the LH2 complexes contain bacteriochlorophyll a, and the core complexes contain bacteriochlorophyll b, it was possible to demonstrate energy transfer from LH2 to the core complexes. These experiments provide a first step along the path toward investigating how changing the architecture of purple bacterial photosynthetic units affects the overall efficiency of light-harvesting.
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Affiliation(s)
- Ritsuko Fujii
- Graduate School of Science, Osaka City University, 3-3-138, Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan.
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46
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Ab initio configuration interaction description of excitation energy transfer between closely packed molecules. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2007.08.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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47
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Didraga C, Malyshev VA, Knoester J. Excitation energy transfer between closely spaced multichromophoric systems: effects of band mixing and intraband relaxation. J Phys Chem B 2007; 110:18818-27. [PMID: 16986872 DOI: 10.1021/jp0569281] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We theoretically analyze the excitation energy transfer between two closely spaced linear molecular J-aggregates, whose excited states are Frenkel excitons. The aggregate with the higher (lower) exciton band edge energy is considered as the donor (acceptor). The celebrated theory of Förster resonance energy transfer (FRET), which relates the transfer rate to the overlap integral of optical spectra, fails in this situation. We point out that, in addition to the well-known fact that the point-dipole approximation breaks down (enabling energy transfer between optically forbidden states), also the perturbative treatment of the electronic interactions between donor and acceptor system, which underlies the Förster approach, in general loses its validity due to overlap of the exciton bands. We therefore propose a nonperturbative method, in which donor and acceptor bands are mixed and the energy transfer is described in terms of a phonon-assisted energy relaxation process between the two new (renormalized) bands. The validity of the conventional perturbative approach is investigated by comparing to the nonperturbative one; in general, this validity improves for lower temperature and larger distances (weaker interactions) between the aggregates. We also demonstrate that the interference between intraband relaxation and energy transfer renders the proper definition of the transfer rate and its evaluation from experiment a complicated issue that involves the initial excitation condition. Our results suggest that the best way of determining this transfer rate between two J-aggregates is to measure the fluorescence kinetics of the acceptor J-band after resonant excitation of the donor J-band.
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Affiliation(s)
- C Didraga
- Institute for Theoretical Physics and Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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48
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Borisov AY. Discrepancy between experimental and theoretical excitation transfer rates in LH2 bacteriochlorophyll-protein complexes of purple bacteria. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 37:143-51. [PMID: 17628796 DOI: 10.1007/s00249-007-0200-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 05/04/2007] [Accepted: 06/11/2007] [Indexed: 10/23/2022]
Abstract
Discrepancy is revealed between the values of excitation transfer times measured experimentally, and those calculated, for the atomic structures of B800 --> B850 bacteriochlorophylls within the LH2 light-harvesting pigment-protein complex of the purple bacterium Rhodopseudomonas acidophila. The value 2.9-3.2 ps for the B800 --> B850 excitation transfer, calculated on the basis of atomic structure of LH2, is about 4-times longer than that measured for this bacterium (0.7 ps). This discrepancy appears common in at least two purple bacteria. Possible sources responsible for this discrepancy are discussed. It may either signify some drawback/s/ in our notions about the precise in vivo structure of LH2 complexes, for example, possible changes of LH2 structure during crystallization, or it may reflect our ignorance of some mechanisms involved in excitation migration.
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Affiliation(s)
- A Y Borisov
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Vorob'ev hills, 119992, Moscow, Russia.
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49
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Pendon ZD, Gibson GN, van der Hoef I, Lugtenburg J, Frank HA. Effect of isomer geometry on the steady-state absorption spectra and femtosecond time-resolved dynamics of carotenoids. J Phys Chem B 2007; 109:21172-9. [PMID: 16853743 DOI: 10.1021/jp0529117] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Steady-state absorption and femtosecond time-resolved optical spectroscopic studies have been carried out on all-trans-beta-carotene, 15,15'-cis-beta-carotene, all-trans-spheroidene, and 13,14-locked-cis-spheroidene. We examine in detail the effect of isomer geometry on the spectroscopic properties and photophysics of the low-lying S(1) (2(1)A(g)(-)) and S(2) (1(1)B(u)(+)) excited states of these molecules. The experiments on 13,14-locked-cis-spheroidene, a molecule incapable of undergoing cis-to-trans isomerization, provide a unique opportunity to examine the role of isomer geometry in controlling excited-state deactivation of carotenoids. The kinetic results have been obtained using both single wavelength transient absorption measurements and global fitting procedures. The overall scheme for the deactivation of these molecules after S(0) --> S(2) photon absorption is decay of S(2) to a vibrationally hot S(1) state, followed by vibrational relaxation within S(1), and finally, S(1) --> S(0) internal conversion back to the ground state. Changes in isomer geometry are shown to lead to small but noticeable alterations in the spectroscopic and kinetic behavior of the molecules. The effects are interpreted in terms of minor alterations in excited-state energy and vibrational coupling upon isomerization that bring about changes in the spectroscopic and kinetic behavior of this biologically important class of pigments.
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Affiliation(s)
- Zeus D Pendon
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA
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50
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Mariño-Ochoa E, Palacios R, Kodis G, Macpherson AN, Gillbro T, Gust D, Moore TA, Moore AL. High-efficiency Energy Transfer from Carotenoids to a Phthalocyanine in an Artificial Photosynthetic Antenna¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2002)0760116heetfc2.0.co2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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