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Kawato S, Sato S, Kitoh-Nishioka H, Saga Y. Spectral changes of light-harvesting complex 2 lacking B800 bacteriochlorophyll a under neutral pH conditions. Photochem Photobiol Sci 2024; 23:871-879. [PMID: 38564166 DOI: 10.1007/s43630-024-00560-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 03/05/2024] [Indexed: 04/04/2024]
Abstract
Exchange of B800 bacteriochlorophyll (BChl) a in light-harvesting complex 2 (LH2) is promising for a better understanding of the mechanism on intracomplex excitation energy transfer of this protein. Structural and spectroscopic properties of LH2 lacking B800 BChl a (B800-depleted LH2), which is an important intermediate protein in the B800 exchange, will be useful to tackle the energy transfer mechanism in LH2 by the B800 exchange strategy. In this study, we report a unique spectral change of B800-depleted LH2, in which the Qy absorption band of B800 BChl a is automatically recovered under neutral pH conditions. This spectral change was facilitated by factors for destabilization of LH2, namely, a detergent, lauryl dimethylamine N-oxide, and an increase in temperature. Spectral analyses in the preparation of an LH2 variant denoted as B800-recovered LH2 indicated that most BChl a that was released by decomposition of part of B800-depleted LH2 was a source of the production of B800-recovered LH2. Characterization of purified B800-recovered LH2 demonstrated that its spectroscopic and structural features was quite similar to those of native LH2. The current results indicate that the recovery of the B800 Qy band of B800-depleted LH2 originates from the combination of decomposition of part of B800-depleted LH2 and in situ reconstitution of BChl a into the B800 binding pockets of residual B800-depleted LH2, resulting in the formation of stable B800-recovered LH2.
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Affiliation(s)
- Shota Kawato
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Shinichi Sato
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Hirotaka Kitoh-Nishioka
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Yoshitaka Saga
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan.
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2
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Toutounji M. Empirical asymmetric phonon sideband due to phonons in the protein matrix present in photosynthetic complexes: Time-domain response theory. BIOPHYSICAL REPORTS 2024; 4:100146. [PMID: 38375357 PMCID: PMC10875334 DOI: 10.1016/j.bpr.2024.100146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/25/2024] [Indexed: 02/21/2024]
Abstract
The phonon spectral density plays a key role in probing the dynamical and spectral behavior of molecular aggregates. One may utilize the intimate connection between the one-phonon profile and the phonon spectral density to extract a plausible form of the spectral density of media with rich structure using advanced optical spectroscopy. The excitonic transition is normally accompanied by a broad, asymmetric phonon-side band due to the coupling to the phonons in the surrounding protein matrix present in photosynthetic complexes. The asymmetry in the one-phonon profile of a homogeneous absorption spectrum and other experiments performed on photosynthetic bacterial reaction centers (BRCs) led the Small group to employ a half-Gaussian distribution function on the red side and half-Lorentzian distribution function on the blue side of the absorption lineshape to account for the one-phonon profile asymmetrical shape and relaxation effects contributing to spectroscopy and dynamics of BRCs at hand. Different research groups successfully employed the theory of Small to simulate their photosynthetic spectral data so they could calculate the homogeneous absorption and hole-burned spectra of photosynthetic complexes. Although this report does not directly use the formulae of homogeneous absorption, hole-burning, and fluorescence line-narrowed spectra of BRCs, and photosynthetic complexes, developed by Hayes-Small, it builds on their idea of the phonon sideband asymmetric shape in deriving an accurate and computationally efficient linear electronic transition dipole moment time correlation function. Besides the compelling tractability and efficiency of this correlation function, it accounts for excitonic coupling and eliminates all the inconsistencies arising in the Hayes-Small theory.
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Affiliation(s)
- Mohamad Toutounji
- College of Science, Department of Chemistry, UAE University, Al-Ain, UAE
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3
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Toutounji M. Homogeneous Dephasing in Photosynthetic Bacterial Reaction Centers: Time Correlation Function Approach. Chemphyschem 2024; 25:e202300335. [PMID: 37953408 DOI: 10.1002/cphc.202300335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/14/2023]
Abstract
A new tractable linear electronic transition dipole moment time correlation function (ETDMTCF) that accurately accounts for electronic dephasing, asymmetry, and width of 1-phonon profile, which the zero-phonon line (ZPL) contributes to it, in Rhodopseudomonas viridis bacterial reaction center is derived. This time correlation function proves to be superior to other frequency-domain expressions in case of strong electron-phonon coupling (which is often the case in bacterial RCs and pigment-protein complexes), many vibrational modes involved, and high temperature, whereby more vibronic and electronic (sequence) transitions would arise. The Fourier transform of this ETDMTCF leads to asymmetric multiphonon profiles composed of Lorentzian distribution and Gaussian distribution on the high- and low-energy sides, respectively, whereby the overtone widths fold themselves with that of the one-phonon profile. This ETDMTCF also features expedient computation in large systems using asymmetric phonon profiles to account correctly for dephasing and pigment-protein interaction (electron-phonon coupling). The derived ETDMTCF allows computing all nonlinear optical signals in both time and frequency domains, through the nonlinear dipole moment time correlation functions (as guided by nonlinear optical response theory) in line with the eight Liouville space pathways. The linear transition dipole moment time correlation function is of a central value as the nonlinear transition dipole moment time correlation function is expressed in terms of the linear transition dipole moment time correlation function, derived herein. One of the great advantages of presenting this ETDMTCF is its applicability to nonlinear transition dipole moment time correlation functions in line with the eight Liouville space pathways needed in computing nonlinear signals. As such, there is more to the utility and applicability of the presented ETDMTCF besides computational expediency and efficiency. Results show good agreement with the reported literature. The intimate connection between a one-phonon profile and the corresponding bath spectral density in photosynthetic complexes is discussed.
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Affiliation(s)
- Mohamad Toutounji
- College of Science, Department of Chemistry, P. O. Box 15551, UAE University, Al-Ain, United Arab Emirate
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4
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Timpmann K, Rätsep M, Freiberg A. Dominant role of excitons in photosynthetic color-tuning and light-harvesting. Front Chem 2023; 11:1231431. [PMID: 37908232 PMCID: PMC10613661 DOI: 10.3389/fchem.2023.1231431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 10/03/2023] [Indexed: 11/02/2023] Open
Abstract
Photosynthesis is a vital process that converts sunlight into energy for the Earth's ecosystems. Color adaptation is crucial for different photosynthetic organisms to thrive in their ecological niches. Although the presence of collective excitons in light-harvesting complexes is well known, the role of delocalized excited states in color tuning and excitation energy transfer remains unclear. This study evaluates the characteristics of photosynthetic excitons in sulfur and non-sulfur purple bacteria using advanced optical spectroscopic techniques at reduced temperatures. The exciton effects in these bacteriochlorophyll a-containing species are generally much stronger than in plant systems that rely on chlorophylls. Their exciton bandwidth varies based on multiple factors such as chromoprotein structure, surroundings of the pigments, carotenoid content, hydrogen bonding, and metal ion inclusion. The study nevertheless establishes a linear relationship between the exciton bandwidth and Qy singlet exciton absorption peak, which in case of LH1 core complexes from different species covers almost 130 nm. These findings provide important insights into bacterial color tuning and light-harvesting, which can inspire sustainable energy strategies and devices.
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Affiliation(s)
- Kõu Timpmann
- Institute of Physics, University of Tartu, Tartu, Estonia
| | - Margus Rätsep
- Institute of Physics, University of Tartu, Tartu, Estonia
| | - Arvi Freiberg
- Institute of Physics, University of Tartu, Tartu, Estonia
- Estonian Academy of Sciences, Tallinn, Estonia
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5
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Saga Y, Hamanishi K. Effects of Detergents on the Spectral Features of B820 Bacteriochlorophyll a in Light-Harvesting Complex 3. ACS OMEGA 2022; 7:29231-29235. [PMID: 36033670 PMCID: PMC9404518 DOI: 10.1021/acsomega.2c03323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
Excitonic coupling of bacteriochlorophyll (BChl) a in light-harvesting (LH) proteins of purple photosynthetic bacteria is key for efficient photon capture and energy transfer. Environmental factors can affect the spectral features of these BChl a pigments and investigating these effects can provide insight into the molecular mechanisms underlying the photosynthetic spectral tuning. The present study analyzes the spectral alterations of the Qy band of B820 BChl a within the LH3 protein in relation to the type and concentration of detergents in the buffer. Changing the detergent from lauryl dimethylamine N-oxide (LDAO) to n-dodecyl-β-d-maltoside (DDM) caused a red shift in the B820 Qy band accompanied by hyperchromism; these spectral alterations were completely reversed by exchanging back from DDM to LDAO. These results reflect the different effects of harsh vs mild detergents on the perturbation of LH3. The B820 Qy band did not change when LDAO or NaCl concentration was altered, suggesting that electrostatic effects by external components have little influence on the spectral features of B820 BChl a in LH3.
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Mao R, Wang X, Gao J. Bridging Carotenoid-to-Bacteriochlorophyll Energy Transfer of Purple Bacteria LH2 With Temperature Variations: Insights From Conformational Changes. Front Chem 2021; 9:764107. [PMID: 34671594 PMCID: PMC8521103 DOI: 10.3389/fchem.2021.764107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 09/20/2021] [Indexed: 11/13/2022] Open
Abstract
Photosynthesis is a key process for converting light energy into chemical energy and providing food for lives on Earth. Understanding the mechanism for the energy transfers could provide insights into regulating energy transfers in photosynthesis and designing artificial photosynthesis systems. Many efforts have been devoted to exploring the mechanism of temperature variations affecting the excitonic properties of LH2. In this study, we performed all-atom molecular dynamics (MD) simulations and quantum mechanics calculations for LH2 complex from purple bacteria along with its membrane environment under three typical temperatures: 270, 300, and 330 K. The structural analysis from validated MD simulations showed that the higher temperature impaired interactions at N-terminus of both α and β polypeptide helices and led to the dissociation of this hetero polypeptide dimer. Rhodopin-β-D-glucosides (RG1) moved centripetally with α polypeptide helices when temperature increased and enlarged their distances with bacteriochlorophylls molecules that have the absorption peak at 850 nm (B850), which resulted in reducing the coupling strengths between RG1 and B850 molecules. The present study reported a cascading mechanism for temperature regulating the energy transfers in LH2 of purple bacteria.
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Affiliation(s)
- Ruichao Mao
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University, Wuhan, China
| | - Xiaocong Wang
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University, Wuhan, China
| | - Jun Gao
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University, Wuhan, China
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7
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Wang ZQ, Zhao QM, Zhong X, Xiao L, Ma LX, Wu CF, Zhang Z, Zhang LQ, Tian Y, Fan W. Comparative analysis of maca (Lepidium meyenii) proteome profiles reveals insights into response mechanisms of herbal plants to high-temperature stress. BMC PLANT BIOLOGY 2020; 20:431. [PMID: 32938390 PMCID: PMC7493174 DOI: 10.1186/s12870-020-02645-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 09/10/2020] [Indexed: 05/14/2023]
Abstract
BACKGROUND High-temperature stress (HTS) is one of the main environmental stresses that limit plant growth and crop production in agricultural systems. Maca (Lepidium meyenii) is an important high-altitude herbaceous plant adapted to a wide range of environmental stimuli such as cold, strong wind and UV-B exposure. However, it is an extremely HTS-sensitive plant species. Thus far, there is limited information about gene/protein regulation and signaling pathways related to the heat stress responses in maca. In this study, proteome profiles of maca seedlings exposed to HTS for 12 h were investigated using a tandem mass tag (TMT)-based proteomic approach. RESULTS In total, 6966 proteins were identified, of which 300 showed significant alterations in expression following HTS. Bioinformatics analyses indicated that protein processing in endoplasmic reticulum was the most significantly up-regulated metabolic pathway following HTS. Quantitative RT-PCR (qRT-PCR) analysis showed that the expression levels of 19 genes encoding proteins mapped to this pathway were significantly up-regulated under HTS. These results show that protein processing in the endoplasmic reticulum may play a crucial role in the responses of maca to HTS. CONCLUSIONS Our proteomic data can be a good resource for functional proteomics of maca and our results may provide useful insights into the molecular response mechanisms underlying herbal plants to HTS.
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Affiliation(s)
- Zhan Qi Wang
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Sciences, Huzhou University, Huzhou, 313000 China
| | - Qi Ming Zhao
- State Key Laboratory of Conservation and Utilization of Bio-resources in Yunnan, The Key Laboratory of Medicinal Plant Biology of Yunnan Province, National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwest China, Yunnan Agricultural University, Kunming, 650201 China
| | - Xueting Zhong
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Sciences, Huzhou University, Huzhou, 313000 China
| | - Li Xiao
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Sciences, Huzhou University, Huzhou, 313000 China
| | - Li Xuan Ma
- College of Food Science and Technology, Yunnan Agricultural University, Kunming, 650201 China
| | - Chou Fei Wu
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Sciences, Huzhou University, Huzhou, 313000 China
| | - Zhongshan Zhang
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Sciences, Huzhou University, Huzhou, 313000 China
| | - Li Qin Zhang
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Sciences, Huzhou University, Huzhou, 313000 China
- Huzhou central hospital, Huzhou University, Huzhou, 313000 China
| | - Yang Tian
- College of Food Science and Technology, Yunnan Agricultural University, Kunming, 650201 China
| | - Wei Fan
- State Key Laboratory of Conservation and Utilization of Bio-resources in Yunnan, The Key Laboratory of Medicinal Plant Biology of Yunnan Province, National & Local Joint Engineering Research Center on Germplasm Innovation & Utilization of Chinese Medicinal Materials in Southwest China, Yunnan Agricultural University, Kunming, 650201 China
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8
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Leiger K, Linnanto JM, Freiberg A. Establishment of the Qy Absorption Spectrum of Chlorophyll a Extending to Near-Infrared. Molecules 2020; 25:molecules25173796. [PMID: 32825445 PMCID: PMC7503670 DOI: 10.3390/molecules25173796] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023] Open
Abstract
A weak absorption tail related to the Qy singlet electronic transition of solvated chlorophyll a is discovered using sensitive anti-Stokes fluorescence excitation spectroscopy. The quasi-exponentially decreasing tail was, at ambient temperature, readily observable as far as -2400 cm-1 from the absorption peak and at relative intensity of 10-7. The tail also weakened rapidly upon cooling the sample, implying its basic thermally activated nature. The shape of the spectrum as well as its temperature dependence were qualitatively well reproduced by quantum chemical calculations involving the pigment intramolecular vibrational modes, their overtones, and pairwise combination modes, but no intermolecular/solvent modes. A similar tail was observed earlier in the case of bacteriochlorophyll a, suggesting generality of this phenomenon. Long vibronic red tails are, thus, expected to exist in all pigments of light-harvesting relevance at physiological temperatures.
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Affiliation(s)
- Kristjan Leiger
- Institute of Physics, University of Tartu, W. Ostwaldi 1, 51011 Tartu, Estonia; (K.L.); (J.M.L.)
| | - Juha Matti Linnanto
- Institute of Physics, University of Tartu, W. Ostwaldi 1, 51011 Tartu, Estonia; (K.L.); (J.M.L.)
| | - Arvi Freiberg
- Institute of Physics, University of Tartu, W. Ostwaldi 1, 51011 Tartu, Estonia; (K.L.); (J.M.L.)
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51014 Tartu, Estonia
- Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia
- Correspondence:
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9
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The chirality origin of retinal-carotenoid complex in gloeobacter rhodopsin: a temperature-dependent excitonic coupling. Sci Rep 2020; 10:13992. [PMID: 32814821 PMCID: PMC7438509 DOI: 10.1038/s41598-020-70697-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 07/29/2020] [Indexed: 11/08/2022] Open
Abstract
Retinal proteins play significant roles in light-induced protons/ions transport across the cell membrane. A recent studied retinal protein, gloeobacter rhodopsin (gR), functions as a proton pump, and binds the carotenoid salinixanthin (sal) in addition to the retinal chromophore. We have studied the interactions between the two chromophores as reflected in the circular dichroism (CD) spectrum of gR complex. gR exhibits a weak CD spectrum but following binding of sal, it exhibits a significant enhancement of the CD bands. To examine the CD origin, we have substituted the retinal chromophore of gR by synthetic retinal analogues, and have concluded that the CD bands originated from excitonic interaction between sal and the retinal chromophore as well as the sal chirality induced by binding to the protein. Temperature increase significantly affected the CD spectra, due to vanishing of excitonic coupling. A similar phenomenon of excitonic interaction lose between chromophores was recently reported for a photosynthetic pigment-protein complex (Nature Commmun, 9, 2018, 99). We propose that the excitonic interaction in gR is weaker due to protein conformational alterations. The excitonic interaction is further diminished following reduction of the retinal protonated Schiff base double bond. Furthermore, the intact structure of the retinal ring is necessary for obtaining the excitonic interaction.
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10
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Kangur L, Rätsep M, Timpmann K, Wang-Otomo ZY, Freiberg A. The two light-harvesting membrane chromoproteins of Thermochromatium tepidum expose distinct robustness against temperature and pressure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148205. [PMID: 32305413 DOI: 10.1016/j.bbabio.2020.148205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/17/2020] [Accepted: 04/14/2020] [Indexed: 01/26/2023]
Abstract
An increased robustness against high temperature and the much red-shifted near-infrared absorption spectrum of excitons in the LH1-RC core pigment-protein complex from the thermophilic photosynthetic purple sulfur bacterium Thermochromatium tepidum has recently attracted much interest. In the present work, thermal and hydrostatic pressure stability of the peripheral LH2 and core LH1-RC complexes from this bacterium were in parallel investigated by various optical spectroscopy techniques applied over a wide spectral range from far-ultraviolet to near-infrared. In contrast to expectations, very distinct robustness of the complexes was established, while the sturdiness of LH2 surpassed that of LH1-RC both with respect to temperatures between 288 and 360 K, and pressures between 1 bar and 14 kbar. Subtle structural variances related to the hydrogen bond network are likely responsible for the extra stability of LH2.
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Affiliation(s)
- Liina Kangur
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
| | - Margus Rätsep
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
| | - Kõu Timpmann
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
| | | | - Arvi Freiberg
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia; Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia; Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia.
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11
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Kaftan D, Bína D, Koblížek M. Temperature dependence of photosynthetic reaction centre activity in Rhodospirillum rubrum. PHOTOSYNTHESIS RESEARCH 2019; 142:181-193. [PMID: 31267356 PMCID: PMC6848049 DOI: 10.1007/s11120-019-00652-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/03/2019] [Indexed: 06/09/2023]
Abstract
The influence of temperature on photosynthetic reactions was investigated by a combination of time-resolved bacteriochlorophyll fluorescence, steady-state and differential absorption spectroscopy, and polarographic respiration measurements in intact cells of purple non-sulphur bacterium Rhodospirillum rubrum. Using variable bacteriochlorophyll fluorescence, it was found that the electron-transport activity increased with the increasing temperature up to 41 °C. The fast and medium components of the fluorescence decay kinetics followed the ideal Arrhenius equation. The calculated activation energy for the fast component was Ea1 = 16 kJ mol-1, while that of the medium component was more than double, with Ea2 = 38 kJ mol-1. At temperatures between 41 and 59 °C, the electron transport was gradually, irreversibly inhibited. Interestingly, the primary charge separation remained fully competent from 20 to 59 °C as documented by both BChl fluorescence and differential absorption spectroscopy of the P870+ signal. At temperatures above 60 °C, the primary photochemistry became reversibly inhibited, which was manifested by an increase in minimal fluorescence, F0, whereas maximal fluorescence, FM, slowly declined. Finally, above 71 °C, the photosynthetic complexes began to disassemble as seen in the decline of all fluorometric parameters and the disappearance of the LH1 absorption band at 880 nm. The extended optimal temperature of photosynthetic reaction centre in a model species of Rhodospirillales adds on the evidence that the good thermostability of the photosynthetic reaction centres is present across all Alphaproteobacteria.
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Affiliation(s)
- David Kaftan
- Center Algatech, Institute of Microbiology CAS, 37981, Třeboň, Czech Republic.
- Faculty of Science, University of South Bohemia, 37005, Ceske Budejovice, Czech Republic.
| | - David Bína
- Faculty of Science, University of South Bohemia, 37005, Ceske Budejovice, Czech Republic
- Biology Centre, Czech Academy of Sciences, Branišovská 31, Ceske Budejovice, Czech Republic
| | - Michal Koblížek
- Center Algatech, Institute of Microbiology CAS, 37981, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 37005, Ceske Budejovice, Czech Republic
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12
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Massey SC, Ting PC, Yeh SH, Dahlberg PD, Sohail SH, Allodi MA, Martin EC, Kais S, Hunter CN, Engel GS. Orientational Dynamics of Transition Dipoles and Exciton Relaxation in LH2 from Ultrafast Two-Dimensional Anisotropy. J Phys Chem Lett 2019; 10:270-277. [PMID: 30599133 DOI: 10.1021/acs.jpclett.8b03223] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Light-harvesting complexes in photosynthetic organisms display fast and efficient energy transfer dynamics, which depend critically on the electronic structure of the coupled chromophores within the complexes and their interactions with their environment. We present ultrafast anisotropy dynamics, resolved in both time and frequency, of the transmembrane light-harvesting complex LH2 from Rhodobacter sphaeroides in its native membrane environment using polarization-controlled two-dimensional electronic spectroscopy. Time-dependent anisotropy obtained from both experiment and modified Redfield simulation reveals an orientational preference for excited state absorption and an ultrafast equilibration within the B850 band in LH2. This ultrafast equilibration is favorable for subsequent energy transfer toward the reaction center. Our results also show a dynamic difference in excited state absorption anisotropy between the directly excited B850 population and the population that is initially excited at 800 nm, suggesting absorption from B850 states to higher-lying excited states following energy transfer from B850*. These results give insight into the ultrafast dynamics of bacterial light harvesting and the excited state energy landscape of LH2 in the native membrane environment.
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Affiliation(s)
- Sara C Massey
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Po-Chieh Ting
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Shu-Hao Yeh
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute , The University of Chicago , Chicago , Illinois 60637 , United States
- Qatar Environment and Energy Research Institute , Hamad Bin Khalifa University , Qatar Foundation, Doha , Qatar
| | - Peter D Dahlberg
- Graduate Program in the Biophysical Sciences, Institute for Biophysical Dynamics, and the James Franck Institute , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Sara H Sohail
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Marco A Allodi
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Elizabeth C Martin
- Department of Molecular Biology and Biotechnology , University of Sheffield , Firth Court, Western Bank, Sheffield S10 2TN , United Kingdom
| | - Sabre Kais
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology , University of Sheffield , Firth Court, Western Bank, Sheffield S10 2TN , United Kingdom
| | - Gregory S Engel
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute , The University of Chicago , Chicago , Illinois 60637 , United States
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