1
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Tani K, Kanno R, Ji XC, Satoh I, Kobayashi Y, Hall M, Yu LJ, Kimura Y, Mizoguchi A, Humbel BM, Madigan MT, Wang-Otomo ZY. Rhodobacter capsulatus forms a compact crescent-shaped LH1-RC photocomplex. Nat Commun 2023; 14:846. [PMID: 36792596 PMCID: PMC9932092 DOI: 10.1038/s41467-023-36460-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 02/01/2023] [Indexed: 02/17/2023] Open
Abstract
Rhodobacter (Rba.) capsulatus has been a favored model for studies of all aspects of bacterial photosynthesis. This purple phototroph contains PufX, a polypeptide crucial for dimerization of the light-harvesting 1-reaction center (LH1-RC) complex, but lacks protein-U, a U-shaped polypeptide in the LH1-RC of its close relative Rba. sphaeroides. Here we present a cryo-EM structure of the Rba. capsulatus LH1-RC purified by DEAE chromatography. The crescent-shaped LH1-RC exhibits a compact structure containing only 10 LH1 αβ-subunits. Four αβ-subunits corresponding to those adjacent to protein-U in Rba. sphaeroides were absent. PufX in Rba. capsulatus exhibits a unique conformation in its N-terminus that self-associates with amino acids in its own transmembrane domain and interacts with nearby polypeptides, preventing it from interacting with proteins in other complexes and forming dimeric structures. These features are discussed in relation to the minimal requirements for the formation of LH1-RC monomers and dimers, the spectroscopic behavior of both the LH1 and RC, and the bioenergetics of energy transfer from LH1 to the RC.
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Affiliation(s)
- Kazutoshi Tani
- Graduate School of Medicine, Mie University, Tsu, Japan.
| | - Ryo Kanno
- Scientific Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-Son, Kunigami-Gun, Okinawa, Japan.,Quantum wave microscopy unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-Son, Kunigami-Gun, Okinawa, Japan
| | | | | | | | - Malgorzata Hall
- Scientific Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-Son, Kunigami-Gun, Okinawa, Japan
| | - Long-Jiang Yu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Yukihiro Kimura
- Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe, Japan
| | | | - Bruno M Humbel
- Scientific Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-Son, Kunigami-Gun, Okinawa, Japan.,Department of Cell Biology and Neuroscience, Juntendo University, Graduate School of Medicine, Tokyo, Japan
| | - Michael T Madigan
- School of Biological Sciences, Department of Microbiology, Southern Illinois University, Carbondale, IL, USA
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2
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Tani K, Kobayashi K, Hosogi N, Ji XC, Nagashima S, Nagashima KVP, Izumida A, Inoue K, Tsukatani Y, Kanno R, Hall M, Yu LJ, Ishikawa I, Okura Y, Madigan MT, Mizoguchi A, Humbel BM, Kimura Y, Wang-Otomo ZY. A Ca 2+-binding motif underlies the unusual properties of certain photosynthetic bacterial core light-harvesting complexes. J Biol Chem 2022; 298:101967. [PMID: 35460693 PMCID: PMC9133646 DOI: 10.1016/j.jbc.2022.101967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 04/16/2022] [Accepted: 04/18/2022] [Indexed: 01/24/2023] Open
Abstract
The mildly thermophilic purple phototrophic bacterium Allochromatium tepidum provides a unique model for investigating various intermediate phenotypes observed between those of thermophilic and mesophilic counterparts. The core light-harvesting (LH1) complex from A. tepidum exhibits an absorption maximum at 890 nm and mildly enhanced thermostability, both of which are Ca2+-dependent. However, it is unknown what structural determinants might contribute to these properties. Here, we present a cryo-EM structure of the reaction center–associated LH1 complex at 2.81 Å resolution, in which we identify multiple pigment-binding α- and β-polypeptides within an LH1 ring. Of the 16 α-polypeptides, we show that six (α1) bind Ca2+ along with β1- or β3-polypeptides to form the Ca2+-binding sites. This structure differs from that of fully Ca2+-bound LH1 from Thermochromatium tepidum, enabling determination of the minimum structural requirements for Ca2+-binding. We also identified three amino acids (Trp44, Asp47, and Ile49) in the C-terminal region of the A. tepidum α1-polypeptide that ligate each Ca ion, forming a Ca2+-binding WxxDxI motif that is conserved in all Ca2+-bound LH1 α-polypeptides from other species with reported structures. The partial Ca2+-bound structure further explains the unusual phenotypic properties observed for this bacterium in terms of its Ca2+-requirements for thermostability, spectroscopy, and phototrophic growth, and supports the hypothesis that A. tepidum may represent a “transitional” species between mesophilic and thermophilic purple sulfur bacteria. The characteristic arrangement of multiple αβ-polypeptides also suggests a mechanism of molecular recognition in the expression and/or assembly of the LH1 complex that could be regulated through interactions with reaction center subunits.
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Affiliation(s)
- Kazutoshi Tani
- Graduate School of Medicine, Mie University, Tsu, Japan.
| | - Kazumi Kobayashi
- EM Business Unit, JEOL Ltd 3-1-2 Musashino, Akishima, Tokyo, Japan
| | - Naoki Hosogi
- EM Business Unit, JEOL Ltd 3-1-2 Musashino, Akishima, Tokyo, Japan
| | | | - Sakiko Nagashima
- Research Institute for Integrated Science, Kanagawa University, Hiratsuka, Kanagawa, Japan
| | - Kenji V P Nagashima
- Research Institute for Integrated Science, Kanagawa University, Hiratsuka, Kanagawa, Japan
| | - Airi Izumida
- Department of Biological Sciences, Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa, Japan
| | - Kazuhito Inoue
- Research Institute for Integrated Science, Kanagawa University, Hiratsuka, Kanagawa, Japan; Department of Biological Sciences, Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa, Japan
| | - Yusuke Tsukatani
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa, Japan
| | - Ryo Kanno
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), Kunigami-gun, Okinawa, Japan
| | - Malgorzata Hall
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), Kunigami-gun, Okinawa, Japan
| | - Long-Jiang Yu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Isamu Ishikawa
- EM Business Unit, JEOL Ltd 3-1-2 Musashino, Akishima, Tokyo, Japan
| | - Yoshihiro Okura
- EM Business Unit, JEOL Ltd 3-1-2 Musashino, Akishima, Tokyo, Japan
| | - Michael T Madigan
- School of Biological Sciences, Department of Microbiology, Southern Illinois University, Carbondale, Illinois, USA
| | | | - Bruno M Humbel
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), Kunigami-gun, Okinawa, Japan
| | - Yukihiro Kimura
- Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe, Japan.
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3
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Gelzinis A, Augulis R, Büchel C, Robert B, Valkunas L. Confronting FCP structure with ultrafast spectroscopy data: evidence for structural variations. Phys Chem Chem Phys 2021; 23:806-821. [PMID: 33427836 DOI: 10.1039/d0cp05578f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diatoms are a major group of algae, responsible for a quarter of the global primary production on our planet. Their adaptation to marine environments is ensured by their light-harvesting antenna - the fucoxanthin-chlorophyll protein (FCP) complex, which absorbs strongly in the blue-green spectral region. Although these essential proteins have been the subject of many studies, for a long time their comprehensive description was not possible in the absence of structural data. Last year, the 3D structures of several FCP complexes were revealed. The structure of an FCP dimer was resolved by crystallography for the pennate diatom Phaeodactylum tricornutum [W. Wang et al., Science, 2019, 363, 6427] and the structure of the PSII supercomplex from the centric diatom Chaetoceros gracilis, containing several FCPs, was obtained by electron microscopy [X. Pi et al., Science, 2019, 365, 6452; R. Nagao et al., Nat. Plants, 2019, 5, 890]. In this Perspective article, we evaluate how precisely these structures may account for previously published ultrafast spectroscopy results, describing the excitation energy transfer in the FCP from another centric diatom Cyclotella meneghiniana. Surprisingly, we find that the published FCP structures cannot explain several observations obtained from ultrafast spectroscopy. Using the available structures, and results from electron microscopy, we construct a trimer-based FCP model for Cyclotella meneghiniana, consistent with ultrafast experimental data. As a whole, our observations suggest that the structures from the proteins belonging to the FCP family display larger variations than the equivalent LHC proteins in plants, which may reflect species-specific adaptations or original strategies for adapting to rapidly changing marine environments.
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Affiliation(s)
- Andrius Gelzinis
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius, Lithuania. and Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Sauletekio 3, 10257 Vilnius, Lithuania
| | - Ramūnas Augulis
- Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Sauletekio 3, 10257 Vilnius, Lithuania
| | - Claudia Büchel
- Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Straβe 9, 60438 Frankfurt, Germany
| | - Bruno Robert
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - Leonas Valkunas
- Institute of Chemical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius, Lithuania. and Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Sauletekio 3, 10257 Vilnius, Lithuania
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4
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Tani K, Kanno R, Makino Y, Hall M, Takenouchi M, Imanishi M, Yu LJ, Overmann J, Madigan MT, Kimura Y, Mizoguchi A, Humbel BM, Wang-Otomo ZY. Cryo-EM structure of a Ca 2+-bound photosynthetic LH1-RC complex containing multiple αβ-polypeptides. Nat Commun 2020; 11:4955. [PMID: 33009385 PMCID: PMC7532537 DOI: 10.1038/s41467-020-18748-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 09/09/2020] [Indexed: 11/13/2022] Open
Abstract
The light-harvesting-reaction center complex (LH1-RC) from the purple phototrophic bacterium Thiorhodovibrio strain 970 exhibits an LH1 absorption maximum at 960 nm, the most red-shifted absorption for any bacteriochlorophyll (BChl) a-containing species. Here we present a cryo-EM structure of the strain 970 LH1-RC complex at 2.82 Å resolution. The LH1 forms a closed ring structure composed of sixteen pairs of the αβ-polypeptides. Sixteen Ca ions are present in the LH1 C-terminal domain and are coordinated by residues from the αβ-polypeptides that are hydrogen-bonded to BChl a. The Ca2+-facilitated hydrogen-bonding network forms the structural basis of the unusual LH1 redshift. The structure also revealed the arrangement of multiple forms of α- and β-polypeptides in an individual LH1 ring. Such organization indicates a mechanism of interplay between the expression and assembly of the LH1 complex that is regulated through interactions with the RC subunits inside. Here the authors report a cryo-EM structure of the light-harvesting-reaction center complex (LH1- RC) from the purple phototrophic bacterium Thiorhodovibrio strain 970, providing insights into the mechanisms that underlie the absorbance properties of both the LH1 and the RC of this spectrally unusual purple bacterium.
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Affiliation(s)
- Kazutoshi Tani
- Graduate School of Medicine, Mie University, Tsu, 514-8507, Japan.
| | - Ryo Kanno
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Yuki Makino
- Faculty of Science, Ibaraki University, Mito, 310-8512, Japan
| | - Malgorzata Hall
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | | | - Michie Imanishi
- Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe, 657-8501, Japan
| | - Long-Jiang Yu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Jörg Overmann
- Leibniz-Institute DSMZ-German Collection of Microorganisms and Cell Cultures, 38124, Braunschweig, Germany.,Faculty of Life Science, Institute of Microbiology, Braunschweig University of Technology, Braunschweig, Germany
| | - Michael T Madigan
- Department of Microbiology, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Yukihiro Kimura
- Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe, 657-8501, Japan
| | - Akira Mizoguchi
- Graduate School of Medicine, Mie University, Tsu, 514-8507, Japan
| | - Bruno M Humbel
- Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
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5
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Pruchyathamkorn J, Kendrick WJ, Frawley AT, Mattioni A, Caycedo‐Soler F, Huelga SF, Plenio MB, Anderson HL. A Complex Comprising a Cyanine Dye Rotaxane and a Porphyrin Nanoring as a Model Light-Harvesting System. Angew Chem Int Ed Engl 2020; 59:16455-16458. [PMID: 32558120 PMCID: PMC7540489 DOI: 10.1002/anie.202006644] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Indexed: 12/03/2022]
Abstract
A nanoring-rotaxane supramolecular assembly with a Cy7 cyanine dye (hexamethylindotricarbocyanine) threaded along the axis of the nanoring was synthesized as a model for the energy transfer between the light-harvesting complex LH1 and the reaction center in purple bacteria photosynthesis. The complex displays efficient energy transfer from the central cyanine dye to the surrounding zinc porphyrin nanoring. We present a theoretical model that reproduces the absorption spectrum of the nanoring and quantifies the excitonic coupling between the nanoring and the central dye, thereby explaining the efficient energy transfer and demonstrating similarity with structurally related natural light-harvesting systems.
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Affiliation(s)
| | - William J. Kendrick
- Department of ChemistryOxford UniversityChemistry Research LaboratoryOxfordOX1 3TAUK
| | - Andrew T. Frawley
- Department of ChemistryOxford UniversityChemistry Research LaboratoryOxfordOX1 3TAUK
| | - Andrea Mattioni
- Institute of Theoretical Physics and IQSTUlm UniversityAlbert-Einstein-Allee 1189069UlmGermany
| | - Felipe Caycedo‐Soler
- Institute of Theoretical Physics and IQSTUlm UniversityAlbert-Einstein-Allee 1189069UlmGermany
| | - Susana F. Huelga
- Institute of Theoretical Physics and IQSTUlm UniversityAlbert-Einstein-Allee 1189069UlmGermany
| | - Martin B. Plenio
- Institute of Theoretical Physics and IQSTUlm UniversityAlbert-Einstein-Allee 1189069UlmGermany
| | - Harry L. Anderson
- Department of ChemistryOxford UniversityChemistry Research LaboratoryOxfordOX1 3TAUK
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6
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Pruchyathamkorn J, Kendrick WJ, Frawley AT, Mattioni A, Caycedo‐Soler F, Huelga SF, Plenio MB, Anderson HL. A Complex Comprising a Cyanine Dye Rotaxane and a Porphyrin Nanoring as a Model Light‐Harvesting System. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
| | - William J. Kendrick
- Department of ChemistryOxford UniversityChemistry Research Laboratory Oxford OX1 3TA UK
| | - Andrew T. Frawley
- Department of ChemistryOxford UniversityChemistry Research Laboratory Oxford OX1 3TA UK
| | - Andrea Mattioni
- Institute of Theoretical Physics and IQSTUlm University Albert-Einstein-Allee 11 89069 Ulm Germany
| | - Felipe Caycedo‐Soler
- Institute of Theoretical Physics and IQSTUlm University Albert-Einstein-Allee 11 89069 Ulm Germany
| | - Susana F. Huelga
- Institute of Theoretical Physics and IQSTUlm University Albert-Einstein-Allee 11 89069 Ulm Germany
| | - Martin B. Plenio
- Institute of Theoretical Physics and IQSTUlm University Albert-Einstein-Allee 11 89069 Ulm Germany
| | - Harry L. Anderson
- Department of ChemistryOxford UniversityChemistry Research Laboratory Oxford OX1 3TA UK
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7
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Chuang C, Brumer P. LH1-RC light-harvesting photocycle under realistic light-matter conditions. J Chem Phys 2020; 152:154101. [PMID: 32321270 DOI: 10.1063/5.0004490] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Quantum master equations are used to simulate the photocycle of the light-harvesting complex 1 (LH1) and the associated reaction center (RC) in purple bacteria excited with natural incoherent light. The influence of the radiation and protein environments and the full photocycle of the complexes, including the charge separation and RC recovery processes, are taken into account. Particular emphasis is placed on the steady state excitation energy transfer rate between the LH1 and the RC and the steady state dependence on the light intensity. The transfer rate is shown to scale linearly with light intensity near the value in the natural habitat and at higher light intensities is found to be bounded by the rate-determining step of the photocycle, the RC recovery rate. Transient (e.g., pulsed laser induced) dynamics, however, shows rates higher than the steady state value and continues to scale linearly with the intensity. The results show a correlation between the transfer rate and the manner in which the donor state is prepared. In addition, the transition from the transient to the steady state results can be understood as a cascade of ever slower rate-determining steps and quasi-stationary states inherent in multi-scale sequential processes. This type of transition of rates is relevant in most light-induced biological machinery.
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Affiliation(s)
- Chern Chuang
- Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Paul Brumer
- Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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8
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Imanishi M, Takenouchi M, Takaichi S, Nakagawa S, Saga Y, Takenaka S, Madigan MT, Overmann J, Wang-Otomo ZY, Kimura Y. A Dual Role for Ca 2+ in Expanding the Spectral Diversity and Stability of Light-Harvesting 1 Reaction Center Photocomplexes of Purple Phototrophic Bacteria. Biochemistry 2019; 58:2844-2852. [PMID: 31145583 DOI: 10.1021/acs.biochem.9b00351] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The light-harvesting 1 reaction center (LH1-RC) complex in the purple sulfur bacterium Thiorhodovibrio ( Trv.) strain 970 cells exhibits its LH1 Q y transition at 973 nm, the lowest-energy Q y absorption among purple bacteria containing bacteriochlorophyll a (BChl a). Here we characterize the origin of this extremely red-shifted Q y transition. Growth of Trv. strain 970 did not occur in cultures free of Ca2+, and elemental analysis of Ca2+-grown cells confirmed that purified Trv. strain 970 LH1-RC complexes contained Ca2+. The LH1 Q y band of Trv. strain 970 was blue-shifted from 959 to 875 nm upon Ca2+ depletion, but the original spectral properties were restored upon Ca2+ reconstitution, which also occurs with the thermophilic purple bacterium Thermochromatium ( Tch.) tepidum. The amino acid sequences of the LH1 α- and β-polypeptides from Trv. strain 970 closely resemble those of Tch. tepidum; however, Ca2+ binding in the Trv. strain 970 LH1-RC occurred more selectively than in Tch. tepidum LH1-RC and with a reduced affinity. Ultraviolet resonance Raman analysis indicated that the number of hydrogen-bonding interactions between BChl a and LH1 proteins of Trv. strain 970 was significantly greater than for Tch. tepidum and that Ca2+ was indispensable for maintaining these bonds. Furthermore, perfusion-induced Fourier transform infrared analyses detected Ca2+-induced conformational changes in the binding site closely related to the unique spectral properties of Trv. strain 970. Collectively, our results reveal an ecological strategy employed by Trv. strain 970 of integrating Ca2+ into its LH1-RC complex to extend its light-harvesting capacity to regions of the near-infrared spectrum unused by other purple bacteria.
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Affiliation(s)
- Michie Imanishi
- Graduate School of Agricultural Science , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Mizuki Takenouchi
- Faculty of Science , Ibaraki University , Bunkyo, Mito 310-8512 , Japan
| | - Shinichi Takaichi
- Faculty of Life Sciences , Tokyo University of Agriculture , Setagaya, Tokyo 156-8502 , Japan
| | - Shiori Nakagawa
- Department of Chemistry , Kindai University , Higashi-Osaka, Osaka 577-8502 , Japan
| | - Yoshitaka Saga
- Department of Chemistry , Kindai University , Higashi-Osaka, Osaka 577-8502 , Japan
| | - Shinji Takenaka
- Graduate School of Agricultural Science , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Michael T Madigan
- Department of Microbiology , Southern Illinois University , Carbondale , Illinois 62901 , United States
| | - Jörg Overmann
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures , 38124 Braunschweig , Germany.,Microbiology , Braunschweig University of Technology , 38106 Braunschweig , Germany
| | | | - Yukihiro Kimura
- Graduate School of Agricultural Science , Kobe University , Nada, Kobe 657-8501 , Japan
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10
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Ma F, Romero E, Jones MR, Novoderezhkin VI, van Grondelle R. Both electronic and vibrational coherences are involved in primary electron transfer in bacterial reaction center. Nat Commun 2019; 10:933. [PMID: 30804346 PMCID: PMC6389996 DOI: 10.1038/s41467-019-08751-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 01/15/2019] [Indexed: 11/09/2022] Open
Abstract
Understanding the mechanism behind the near-unity efficiency of primary electron transfer in reaction centers is essential for designing performance-enhanced artificial solar conversion systems to fulfill mankind’s growing demands for energy. One of the most important challenges is distinguishing electronic and vibrational coherence and establishing their respective roles during charge separation. In this work we apply two-dimensional electronic spectroscopy to three structurally-modified reaction centers from the purple bacterium Rhodobacter sphaeroides with different primary electron transfer rates. By comparing dynamics and quantum beats, we reveal that an electronic coherence with dephasing lifetime of ~190 fs connects the initial excited state, P*, and the charge-transfer intermediate \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{P}}_{\mathrm{A}}^ + {\mathrm{P}}_{\mathrm{B}}^ -$$\end{document}PA+PB-; this \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{P}}^ \ast \to {\mathrm{P}}_{\mathrm{A}}^ + {\mathrm{P}}_{\mathrm{B}}^ -$$\end{document}P*→PA+PB- step is associated with a long-lived quasi-resonant vibrational coherence; and another vibrational coherence is associated with stabilizing the primary photoproduct, \documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{P}}^ + {\mathrm{B}}_{\mathrm{A}}^ -$$\end{document}P+BA-. The results show that both electronic and vibrational coherences are involved in primary electron transfer process and they correlate with the super-high efficiency. Distinguishing electronic and vibrational coherences helps to clarify the near-unity efficiency of primary electron transfer in reaction centres. Here, the authors report their respective correlation with the electron transfer rate by comparing the 2D electronic spectra of three mutant reaction centres.
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Affiliation(s)
- Fei Ma
- Department of Biophysics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
| | - Elisabet Romero
- Department of Biophysics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Michael R Jones
- School of Biochemistry, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Vladimir I Novoderezhkin
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
| | - Rienk van Grondelle
- Department of Biophysics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
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11
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Kimura Y, Hashimoto K, Akimoto S, Takenouchi M, Suzuki K, Kishi R, Imanishi M, Takenaka S, Madigan MT, Nagashima KVP, Wang-Otomo ZY. Biochemical and Spectroscopic Characterizations of a Hybrid Light-Harvesting Reaction Center Core Complex. Biochemistry 2018; 57:4496-4503. [PMID: 29965735 DOI: 10.1021/acs.biochem.8b00644] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The light-harvesting 1 reaction center (LH1-RC) complex from Thermochromatium tepidum exhibits a largely red-shifted LH1 Q y absorption at 915 nm due to binding of Ca2+, resulting in an "uphill" energy transfer from LH1 to the reaction center (RC). In a recent study, we developed a heterologous expression system (strain TS2) to construct a functional hybrid LH1-RC with LH1 from Tch. tepidum and the RC from Rhodobacter sphaeroides [Nagashima, K. V. P., et al. (2017) Proc. Natl. Acad. Sci. U. S. A. 114, 10906]. Here, we present detailed characterizations of the hybrid LH1-RC from strain TS2. Effects of metal cations on the phototrophic growth of strain TS2 revealed that Ca2+ is an indispensable element for its growth, which is also true for Tch. tepidum but not for Rba. sphaeroides. The thermal stability of the TS2 LH1-RC was strongly dependent on Ca2+ in a manner similar to that of the native Tch. tepidum, but interactions between the heterologous LH1 and RC became relatively weaker in strain TS2. A Fourier transform infrared analysis demonstrated that the Ca2+-binding site of TS2 LH1 was similar but not identical to that of Tch. tepidum. Steady-state and time-resolved fluorescence measurements revealed that the uphill energy transfer rate from LH1 to the RC was related to the energy gap in an order of Rba. sphaeroides, Tch. tepidum, and strain TS2; however, the quantum yields of LH1 fluorescence did not exhibit such a correlation. On the basis of these findings, we discuss the roles of Ca2+, interactions between LH1 and the RC from different species, and the uphill energy transfer mechanisms.
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Affiliation(s)
- Yukihiro Kimura
- Department of Agrobioscience, Graduate School of Agriculture , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Kanako Hashimoto
- Department of Agrobioscience, Graduate School of Agriculture , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Seiji Akimoto
- Department of Science, Graduate School of Science , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Mizuki Takenouchi
- Faculty of Science , Ibaraki University , Bunkyo, Mito 310-8512 , Japan
| | - Kengo Suzuki
- Hamamatsu Photonics K. K. , Joko-cho, Hamamatsu 431-3196 , Japan
| | - Rikako Kishi
- Department of Agrobioscience, Graduate School of Agriculture , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Michie Imanishi
- Department of Agrobioscience, Graduate School of Agriculture , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Shinji Takenaka
- Department of Agrobioscience, Graduate School of Agriculture , Kobe University , Nada, Kobe 657-8501 , Japan
| | - Michael T Madigan
- Department of Microbiology , Southern Illinois University , Carbondale , Illinois 62901 , United States
| | - Kenji V P Nagashima
- Research Institute for Photobiological Hydrogen Production , Kanagawa University , Tsuchiya, Hiratsuka 259-1293 , Japan
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12
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Ma F, Romero E, Jones MR, Novoderezhkin VI, van Grondelle R. Vibronic Coherence in the Charge Separation Process of the Rhodobacter sphaeroides Reaction Center. J Phys Chem Lett 2018; 9:1827-1832. [PMID: 29584941 PMCID: PMC6023262 DOI: 10.1021/acs.jpclett.8b00108] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/27/2018] [Indexed: 05/19/2023]
Abstract
Two-dimensional electronic spectroscopy was applied to a variant of the reaction center (RC) of purple bacterium Rhodobacter sphaeroides lacking the primary acceptor ubiquinone in order to understand the ultrafast separation and transfer of charge between the bacteriochlorin cofactors. For the first time, characteristic 2D spectra were obtained for the participating excited and charge-transfer states, and the electron-transfer cascade (including two different channels, the P* and B* channels) was fully mapped. By analyzing quantum beats using 2D frequency maps, excited-state vibrational modes at 153 and 33 cm-1 were identified. We speculate that these modes couple to the charge separation (CS) process and collectively optimize the CS and are responsible for the superhigh efficiency.
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Affiliation(s)
- Fei Ma
- Department of Physics and Astronomy , Faculty of Sciences, VU University Amsterdam , De Boelelaan 1081 , 1081 HV Amsterdam , The Netherlands
| | - Elisabet Romero
- Department of Physics and Astronomy , Faculty of Sciences, VU University Amsterdam , De Boelelaan 1081 , 1081 HV Amsterdam , The Netherlands
| | - Michael R Jones
- School of Biochemistry , University of Bristol , Biomedical Sciences Building, University Walk, Bristol BS8 1TD , United Kingdom
| | - Vladimir I Novoderezhkin
- A. N. Belozersky Institute of Physico-Chemical Biology , Moscow State University , Leninskie Gory , 119992 Moscow , Russia
| | - Rienk van Grondelle
- Department of Physics and Astronomy , Faculty of Sciences, VU University Amsterdam , De Boelelaan 1081 , 1081 HV Amsterdam , The Netherlands
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13
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Rätsep M, Timpmann K, Kawakami T, Wang-Otomo ZY, Freiberg A. Spectrally Selective Spectroscopy of Native Ca-Containing and Ba-Substituted LH1-RC Core Complexes from Thermochromatium tepidum. J Phys Chem B 2017; 121:10318-10326. [PMID: 29058423 DOI: 10.1021/acs.jpcb.7b07841] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The LH1-RC core complex from the thermophilic photosynthetic purple sulfur bacterium Thermochromatium tepidum has recently attracted interest of many researchers because of its several unique properties, such as increased robustness against environmental hardships and the much red-shifted near-infrared absorption spectrum of the LH1 antenna exciton polarons. The known near-atomic-resolution crystal structure of the complex well supported this attention. Yet several mechanistic aspects of the complex prominence remained to be understood. In this work, samples of the native, Ca2+-containing core complexes were investigated along with those destabilized by Ba2+ substitution, using various spectrally selective steady-state and picosecond time-resolved spectroscopic techniques at physiological and cryogenic temperatures. As a result, the current interpretation of exciton spectra of the complex was significantly clarified. Specifically, by evaluating the homogeneous and inhomogeneous compositions of the spectra, we showed that there is little to no effect of cation substitution on the dynamic or kinetic properties of antenna excitons. Reasons of the extra red shift of absorption/fluorescence spectra observed in the Ca-LH1-RC and not in the Ba-LH1-RC complex should thus be searched in subtle structural differences following the inclusion of different cations into the core complex scaffold.
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Affiliation(s)
- 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
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14
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Probing structure-function relationships in early events in photosynthesis using a chimeric photocomplex. Proc Natl Acad Sci U S A 2017; 114:10906-10911. [PMID: 28935692 DOI: 10.1073/pnas.1703584114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The native core light-harvesting complex (LH1) from the thermophilic purple phototrophic bacterium Thermochromatium tepidum requires Ca2+ for its thermal stability and characteristic absorption maximum at 915 nm. To explore the role of specific amino acid residues of the LH1 polypeptides in Ca-binding behavior, we constructed a genetic system for heterologously expressing the Tch. tepidum LH1 complex in an engineered Rhodobacter sphaeroides mutant strain. This system contained a chimeric pufBALM gene cluster (pufBA from Tch. tepidum and pufLM from Rba. sphaeroides) and was subsequently deployed for introducing site-directed mutations on the LH1 polypeptides. All mutant strains were capable of phototrophic (anoxic/light) growth. The heterologously expressed Tch. tepidum wild-type LH1 complex was isolated in a reaction center (RC)-associated form and displayed the characteristic absorption properties of this thermophilic phototroph. Spheroidene (the major carotenoid in Rba. sphaeroides) was incorporated into the Tch. tepidum LH1 complex in place of its native spirilloxanthins with one carotenoid molecule present per αβ-subunit. The hybrid LH1-RC complexes expressed in Rba. sphaeroides were characterized using absorption, fluorescence excitation, and resonance Raman spectroscopy. Site-specific mutagenesis combined with spectroscopic measurements revealed that α-D49, β-L46, and a deletion at position 43 of the α-polypeptide play critical roles in Ca binding in the Tch. tepidum LH1 complex; in contrast, α-N50 does not participate in Ca2+ coordination. These findings build on recent structural data obtained from a high-resolution crystallographic structure of the membrane integrated Tch. tepidum LH1-RC complex and have unambiguously identified the location of Ca2+ within this key antenna complex.
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15
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Powell DD, Wasielewski MR, Ratner MA. Redfield Treatment of Multipathway Electron Transfer in Artificial Photosynthetic Systems. J Phys Chem B 2017; 121:7190-7203. [PMID: 28661144 DOI: 10.1021/acs.jpcb.7b02748] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Coherence effects on electron transfer in a series of symmetric and asymmetric two-, three-, four-, and five-site molecular model systems for photosystem I in cyanobacteria and green plants were studied. The total site energies of the electronic Hamiltonian were calculated using the density functional theory (DFT) formalism and included the zero point vibrational energies of the electron donors and acceptors. Site energies and couplings were calculated using a polarizable continuum model to represent various solvent environments, and the site-to-site couplings were calculated using fragment charge difference methods at the DFT level of theory. The Redfield formalism was used to propagate the electron density from the donors to the acceptors, incorporating relaxation and dephasing effects to describe the electron transfer processes. Changing the relative energies of the donor, intermediate acceptor, and final acceptor molecules in these assemblies has profound effects on the electron transfer rates as well as on the amplitude of the quantum oscillations observed. Increasing the ratio of a particular energy gap to the electronic coupling for a given pair of states leads to weaker quantum oscillations between sites. Biasing the intermediate acceptor energies to slightly favor one pathway leads to a general decrease in electron transfer yield.
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Affiliation(s)
- Daniel D Powell
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center Northwestern University , Evanston, Illinois 60208-3113, United States
| | - Mark A Ratner
- Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center Northwestern University , Evanston, Illinois 60208-3113, United States
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16
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Ma F, Yu LJ, Llansola-Portoles MJ, Robert B, Wang-Otomo ZY, van Grondelle R. Metal Cations Induced αβ-BChl a
Heterogeneity in LH1 as Revealed by Temperature-Dependent Fluorescence Splitting. Chemphyschem 2017; 18:2295-2301. [DOI: 10.1002/cphc.201700551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 06/09/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Fei Ma
- Department of Biophysics; Faculty of Sciences; VU University Amsterdam; De Boelelaan 1081 1081 HV Amsterdam The Netherlands
| | - Long-Jiang Yu
- Faculty of Science; Ibaraki University; Mito Ibaraki 310-8512 Japan
| | - Manuel J. Llansola-Portoles
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS; Univ Paris-Sud, Université Paris-Saclay; F-91198 Gif-sur-Yvette cedex France
| | - Bruno Robert
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS; Univ Paris-Sud, Université Paris-Saclay; F-91198 Gif-sur-Yvette cedex France
| | | | - Rienk van Grondelle
- Department of Biophysics; Faculty of Sciences; VU University Amsterdam; De Boelelaan 1081 1081 HV Amsterdam The Netherlands
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17
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Ma F, Yu LJ, Hendrikx R, Wang-Otomo ZY, van Grondelle R. Excitonic and Vibrational Coherence in the Excitation Relaxation Process of Two LH1 Complexes as Revealed by Two-Dimensional Electronic Spectroscopy. J Phys Chem Lett 2017; 8:2751-2756. [PMID: 28585830 DOI: 10.1021/acs.jpclett.7b00824] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ultrafast excitation relaxation within a manifold exciton state and long-lived vibrational coherence are two universal characteristics of photosynthetic antenna complexes. In this work, we studied the two-dimensional electronic spectra of two core light-harvesting (LH1) complexes of Thermochromatium (Tch.) tepidum, native Ca2+-LH1 and modified Ba2+-LH1. The role of the vibrational coherence in the exciton relaxation was revealed by comparing the two LH1 with similar structures but different electronic properties and by the evolution of the exciton and vibrational coherence as a function of temperature.
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Affiliation(s)
- Fei Ma
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam , De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Long-Jiang Yu
- Faculty of Science, Ibaraki University , Mito, Ibaraki 310-8512, Japan
- Research Institute for Interdisciplinary Science, Okayama University , 3-1-1 Tsushima Naka, Okayama 700-8530, Japan
| | - Ruud Hendrikx
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam , De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | | | - Rienk van Grondelle
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam , De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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