1
|
Nagao R, Ueno Y, Furutani M, Kato K, Shen JR, Akimoto S. Biochemical and spectroscopic characterization of PSI-LHCI from the red alga Cyanidium caldarium. PHOTOSYNTHESIS RESEARCH 2023; 156:315-323. [PMID: 36781711 DOI: 10.1007/s11120-023-00999-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/12/2023] [Indexed: 05/23/2023]
Abstract
Light-harvesting complexes (LHCs) have been diversified in oxygenic photosynthetic organisms, and play an essential role in capturing light energy which is transferred to two types of photosystem cores to promote charge-separation reactions. Red algae are one of the groups of photosynthetic eukaryotes, and their chlorophyll (Chl) a-binding LHCs are specifically associated with photosystem I (PSI). In this study, we purified three types of preparations, PSI-LHCI supercomplexes, PSI cores, and isolated LHCIs, from the red alga Cyanidium caldarium, and examined their properties. The polypeptide bands of PSI-LHCI showed characteristic PSI and LHCI components without contamination by other proteins. The carotenoid composition of LHCI displayed zeaxanthins, β-cryptoxanthins, and β-carotenes. Among the carotenoids, zeaxanthins were enriched in LHCI. On the contrary, both zeaxanthins and β-cryptoxanthins could not be detected from PSI, suggesting that zeaxanthins and β-cryptoxanthins are bound to LHCI but not PSI. A Qy peak of Chl a in the absorption spectrum of LHCI was shifted to a shorter wavelength than those in PSI and PSI-LHCI. This tendency is in line with the result of fluorescence-emission spectra, in which the emission maxima of PSI-LHCI, PSI, and LHCI appeared at 727, 719, and 677 nm, respectively. Time-resolved fluorescence spectra of LHCI represented no 719 and 727-nm fluorescence bands from picoseconds to nanoseconds. These results indicate that energy levels of Chls around/within LHCIs and within PSI are changed by binding LHCIs to PSI. Based on these findings, we discuss the expression, function, and structure of red algal PSI-LHCI supercomplexes.
Collapse
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama-shi, Okayama, 700-8530, Japan.
- Faculty of Agriculture, Shizuoka University, Shizuoka-shi, Shizuoka, 422-8529, Japan.
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe-shi, Hyogo, 657-8501, Japan
- Institute of Arts and Science, Tokyo University of Science, Shinjyuku-ku, Tokyo, 162-8601, Japan
| | - Miyu Furutani
- Graduate School of Science, Kobe University, Kobe-shi, Hyogo, 657-8501, Japan
| | - Koji Kato
- Structural Biology Division, Japan Synchrotron Radiation Research Institute (JASRI), Sayo-Gun, Hyogo, 679-5198, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama-shi, Okayama, 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe-shi, Hyogo, 657-8501, Japan.
| |
Collapse
|
2
|
Structure of a tetrameric photosystem I from a glaucophyte alga Cyanophora paradoxa. Nat Commun 2022; 13:1679. [PMID: 35354806 PMCID: PMC8967866 DOI: 10.1038/s41467-022-29303-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/24/2022] [Indexed: 11/08/2022] Open
Abstract
Photosystem I (PSI) is one of the two photosystems functioning in light-energy harvesting, transfer, and electron transfer in photosynthesis. However, the oligomerization state of PSI is variable among photosynthetic organisms. We present a 3.8-Å resolution cryo-electron microscopic structure of tetrameric PSI isolated from the glaucophyte alga Cyanophora paradoxa, which reveals differences with PSI from other organisms in subunit composition and organization. The PSI tetramer is organized in a dimer of dimers with a C2 symmetry. Unlike cyanobacterial PSI tetramers, two of the four monomers are rotated around 90°, resulting in a completely different pattern of monomer-monomer interactions. Excitation-energy transfer among chlorophylls differs significantly between Cyanophora and cyanobacterial PSI tetramers. These structural and spectroscopic features reveal characteristic interactions and excitation-energy transfer in the Cyanophora PSI tetramer, suggesting that the Cyanophora PSI could represent a turning point in the evolution of PSI from prokaryotes to eukaryotes.
Collapse
|
3
|
Nagao R, Yokono M, Kato KH, Ueno Y, Shen JR, Akimoto S. High-light modification of excitation-energy-relaxation processes in the green flagellate Euglena gracilis. PHOTOSYNTHESIS RESEARCH 2021; 149:303-311. [PMID: 34037905 DOI: 10.1007/s11120-021-00849-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/13/2021] [Indexed: 06/12/2023]
Abstract
Photosynthetic organisms finely tune their photosynthetic machinery including pigment compositions and antenna systems to adapt to various light environments. However, it is poorly understood how the photosynthetic machinery in the green flagellate Euglena gracilis is modified under high-light conditions. In this study, we examined high-light modification of excitation-energy-relaxation processes in Euglena cells. Oxygen-evolving activity in the cells incubated at 300 µmol photons m-2 s-1 (HL cells) cannot be detected, reflecting severe photodamage to photosystem II (PSII) in vivo. Pigment compositions in the HL cells showed relative increases in 9'-cis-neoxanthin, diadinoxanthin, and chlorophyll b compared with the cells incubated at 30 µmol photons m-2 s-1 (LL cells). Absolute fluorescence spectra at 77 K exhibit smaller intensities of the PSII and photosystem I (PSI) fluorescence in the HL cells than in the LL cells. Absolute fluorescence decay-associated spectra at 77 K of the HL cells indicate suppression of excitation-energy transfer from light-harvesting complexes (LHCs) to both PSI and PSII with the time constant of 40 ps. Rapid energy quenching in LHCs and PSII in the HL cells is distinctly observed by averaged Chl-fluorescence lifetimes. These findings suggest that Euglena modifies excitation-energy-relaxation processes in addition to pigment compositions to deal with excess energy. These results provide insights into the photoprotection strategies of this alga under high-light conditions.
Collapse
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Hokkaido, 060-0819, Japan
| | - Ka-Ho Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan.
| |
Collapse
|
4
|
Giovagnetti V, Ruban AV. The mechanism of regulation of photosystem I cross-section in the pennate diatom Phaeodactylum tricornutum. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:561-575. [PMID: 33068431 DOI: 10.1093/jxb/eraa478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Photosystems possess distinct fluorescence emissions at low (77K) temperature. PSI emits in the long-wavelength region at ~710-740 nm. In diatoms, a successful clade of marine primary producers, the contribution of PSI-associated emission (710-717 nm) has been shown to be relatively small. However, in the pennate diatom Phaeodactylum tricornutum, the source of the long-wavelength emission at ~710 nm (F710) remains controversial. Here, we addressed the origin and modulation of F710 fluorescence in this alga grown under continuous and intermittent light. The latter condition led to a strong enhancement in F710. Biochemical and spectral properties of the photosynthetic complexes isolated from thylakoid membranes were investigated for both culture conditions. F710 emission appeared to be associated with PSI regardless of light acclimation. To further assess whether PSII could also contribute to this emission, we decreased the concentration of PSII reaction centres and core antenna by growing cells with lincomycin, a chloroplast protein synthesis inhibitor. The treatment did not diminish F710 fluorescence. Our data suggest that F710 emission originates from PSI under the conditions tested and is enhanced in intermittent light-grown cells due to increased energy flow from the FCP antenna to PSI.
Collapse
Affiliation(s)
- Vasco Giovagnetti
- Department of Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Alexander V Ruban
- Department of Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| |
Collapse
|
5
|
Nagao R, Yokono M, Ueno Y, Suzuki T, Kumazawa M, Kato KH, Tsuboshita N, Dohmae N, Ifuku K, Shen JR, Akimoto S. Enhancement of excitation-energy quenching in fucoxanthin chlorophyll a/c-binding proteins isolated from a diatom Phaeodactylum tricornutum upon excess-light illumination. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2021; 1862:148350. [PMID: 33285102 DOI: 10.1016/j.bbabio.2020.148350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/06/2020] [Accepted: 11/27/2020] [Indexed: 10/22/2022]
Abstract
Photosynthetic organisms regulate pigment composition and molecular oligomerization of light-harvesting complexes in response to solar light intensities, in order to improve light-harvesting efficiency. Here we report excitation-energy dynamics and relaxation of fucoxanthin chlorophyll a/c-binding protein (FCP) complexes isolated from a diatom Phaeodactylum tricornutum grown under high-light (HL) illumination. Two types of FCP complexes were prepared from this diatom under the HL condition, whereas one FCP complex was isolated from the cells grown under a low-light (LL) condition. The subunit composition and oligomeric states of FCP complexes under the HL condition are different from those under the LL condition. Absorption and fluorescence spectra at 77 K of the FCP complexes also vary between the two conditions, indicating modifications of the pigment composition and arrangement upon the HL illumination. Time-resolved fluorescence curves at 77 K of the FCP complexes under the HL condition showed shorter lifetime components compared with the LL condition. Fluorescence decay-associated spectra at 77 K showed distinct excitation-energy-quenching components and alterations of energy-transfer pathways in the FCP complexes under the HL condition. These findings provide insights into molecular and functional mechanisms of the dynamic regulation of FCPs in this diatom under excess-light conditions.
Collapse
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Hokkaido 060-0819, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Hyogo 657-8501, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Minoru Kumazawa
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Ka-Ho Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Naoki Tsuboshita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Kentaro Ifuku
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Hyogo 657-8501, Japan.
| |
Collapse
|
6
|
Akimoto S, Ueno Y, Yokono M, Shen JR, Nagao R. Adaptation of light-harvesting and energy-transfer processes of a diatom Chaetoceros gracilis to different light qualities. PHOTOSYNTHESIS RESEARCH 2020; 146:87-93. [PMID: 31970552 DOI: 10.1007/s11120-020-00713-2] [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: 11/18/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
Diatoms are a major group of microalgae in marine and freshwater environments. To utilize the light energy in blue to green region, diatoms possess unique antenna pigment-protein complexes, fucoxanthin chlorophyll a/c-binding proteins (FCPs). Depending on light qualities and quantities, diatoms form FCPs with different energies: normal-type and red-shifted FCPs. In the present study, we examined changes in light-harvesting and energy-transfer processes of a diatom Chaetoceros gracilis cells grown using white- and single-colored light-emitting diodes (LEDs), by means of time-resolved fluorescence spectroscopy. The blue LED, which is harvested by FCPs, modified energy transfer involving CP47, and suppressed energy transfer to PSI. Under the red-LED conditions, which is absorbed by both FCPs and PSs, energy transfer to PSI was enhanced, and the red-shifted FCP appeared. The red-shifted FCP was also recognized under the green- and yellow-LEDs, suggesting that lack of the shorter-wavelength light induces the red-shifted FCP. Functions of the red-shifted FCPs are discussed.
Collapse
Affiliation(s)
- Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan.
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Makio Yokono
- Innovation Center, Nippon Flour Mills Co., Ltd, Atsugi, 243-0041, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
| |
Collapse
|
7
|
Nagao R, Ueno Y, Akimoto S, Shen JR. Effects of CO 2 and temperature on photosynthetic performance in the diatom Chaetoceros gracilis. PHOTOSYNTHESIS RESEARCH 2020; 146:189-195. [PMID: 32114648 DOI: 10.1007/s11120-020-00729-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 02/18/2020] [Indexed: 06/10/2023]
Abstract
CO2 concentration and temperature for growth of photosynthetic organisms are two important factors to ensure better photosynthetic performance. In this study, we investigated the effects of CO2 concentration and temperature on the photosynthetic performance in a marine centric diatom Chaetoceros gracilis. Cells were grown under four different conditions, namely, at 25 °C with air bubbling, at 25 °C with a supplementation of 3% CO2, at 30 °C with air bubbling, and at 30 °C with the CO2 supplementation. It was found that the growth rate of cells at 30 °C with the CO2 supplementation is faster than those at other three conditions. The pigment compositions of cells grown under the different conditions are altered, and fluorescence spectra measured at 77 K also showed different peak positions. A novel fucoxanthin chlorophyll a/c-binding protein complex is observed in the cells grown at 30 °C with the CO2 supplementation but not in the other three types of cells. Since oxygen-evolving activities of the four types of cells are almost unchanged, it is suggested that the CO2 supplementation and growth temperature are involved in the regulation of photosynthetic light-harvesting apparatus in C. gracilis at different degrees. Based on these observations, we discuss the favorable growth conditions for C. gracilis.
Collapse
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
| |
Collapse
|
8
|
Structural basis for energy transfer in a huge diatom PSI-FCPI supercomplex. Nat Commun 2020; 11:5081. [PMID: 33033236 PMCID: PMC7545214 DOI: 10.1038/s41467-020-18867-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 09/17/2020] [Indexed: 01/13/2023] Open
Abstract
Diatom is an important group of marine algae and contributes to around 20% of the global photosynthetic carbon fixation. Photosystem I (PSI) of diatoms is associated with a large number of fucoxanthin-chlorophyll a/c proteins (FCPIs). We report the structure of PSI-FCPI from a diatom Chaetoceros gracilis at 2.38 Å resolution by single-particle cryo-electron microscopy. PSI-FCPI is a monomeric supercomplex consisting of 12 core and 24 antenna subunits (FCPIs), and 326 chlorophylls a, 34 chlorophylls c, 102 fucoxanthins, 35 diadinoxanthins, 18 β-carotenes and some electron transfer cofactors. Two subunits designated PsaR and PsaS were found in the core, whereas several subunits were lost. The large number of pigments constitute a unique and huge network ensuring efficient energy harvesting, transfer and dissipation. These results provide a firm structural basis for unraveling the mechanisms of light-energy harvesting, transfer and quenching in the diatom PSI-FCPI, and also important clues to evolutionary changes of PSI-LHCI. Diatoms are marine algae with an important role in global photosynthetic carbon fixation. Here, the authors present the 2.38 Å cryo-EM structure of photosystem I (PSI) in complex with its 24 fucoxanthin chlorophyll a/c-binding (FCPI) antenna proteins from the diatom Chaetoceros gracilis, which provides mechanistic insights into light-energy harvesting, transfer and quenching of the PSI-FCPI supercomplex.
Collapse
|
9
|
Basic pH-induced modification of excitation-energy dynamics in fucoxanthin chlorophyll a/c-binding proteins isolated from a pinguiophyte, Glossomastix chrysoplasta. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148306. [PMID: 32926861 DOI: 10.1016/j.bbabio.2020.148306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/03/2020] [Accepted: 09/09/2020] [Indexed: 11/20/2022]
Abstract
Photosynthetic organisms have diversified light-harvesting complexes (LHCs) to collect solar energy efficiently, leading to an acquisition of their ecological niches. Herein we report on biochemical and spectroscopic characterizations of fucoxanthin chlorophyll a/c-binding protein (FCP) complexes isolated from a marine pinguiophyte Glossomastix chrysoplasta. The pinguiophyte FCP showed one subunit band in SDS-PAGE and one protein-complex band with a molecular weight at around 66 kDa in clear-native PAGE. By HPLC analysis, the FCP possesses chlorophylls a and c, fucoxanthin, and violaxanthin. To clarify excitation-energy-relaxation processes in the FCP, we measured time-resolved fluorescence spectra at 77 K of the FCP adapted to pH 5.0, 6.5, and 8.0. Fluorescence curves measured at pH 5.0 and 8.0 showed shorter lifetime components compared with those at pH 6.5. The rapid decay components at pH 5.0 and 8.0 are unveiled by fluorescence decay-associated (FDA) spectra; fluorescence decays occur in the 270 and 160-ps FDA spectra only at pH 5.0 and 8.0, respectively. In addition, energy-transfer pathways with time constants of tens of picoseconds are altered under the basic pH condition but not the acidic pH condition. These findings provide novel insights into pH-dependent energy-transfer and energy-quenching machinery in not only FCP family but also photosynthetic LHCs.
Collapse
|
10
|
Nagao R, Yokono M, Ueno Y, Shen JR, Akimoto S. Acidic pH-Induced Modification of Energy Transfer in Diatom Fucoxanthin Chlorophyll a/c-Binding Proteins. J Phys Chem B 2020; 124:4919-4923. [DOI: 10.1021/acs.jpcb.0c04231] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| |
Collapse
|
11
|
Nagao R, Kato K, Ifuku K, Suzuki T, Kumazawa M, Uchiyama I, Kashino Y, Dohmae N, Akimoto S, Shen JR, Miyazaki N, Akita F. Structural basis for assembly and function of a diatom photosystem I-light-harvesting supercomplex. Nat Commun 2020; 11:2481. [PMID: 32424145 PMCID: PMC7235021 DOI: 10.1038/s41467-020-16324-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/27/2020] [Indexed: 11/09/2022] Open
Abstract
Photosynthetic light-harvesting complexes (LHCs) play a pivotal role in collecting solar energy for photochemical reactions in photosynthesis. One of the major LHCs are fucoxanthin chlorophyll a/c-binding proteins (FCPs) present in diatoms, a group of organisms having important contribution to the global carbon cycle. Here, we report a 2.40-Å resolution structure of the diatom photosystem I (PSI)-FCPI supercomplex by cryo-electron microscopy. The supercomplex is composed of 16 different FCPI subunits surrounding a monomeric PSI core. Each FCPI subunit showed different protein structures with different pigment contents and binding sites, and they form a complicated pigment-protein network together with the PSI core to harvest and transfer the light energy efficiently. In addition, two unique, previously unidentified subunits were found in the PSI core. The structure provides numerous insights into not only the light-harvesting strategy in diatom PSI-FCPI but also evolutionary dynamics of light harvesters among oxyphototrophs.
Collapse
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Koji Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Kentaro Ifuku
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Minoru Kumazawa
- Faculty of Agriculture, Kyoto University, Kyoto, 606-8502, Japan
| | - Ikuo Uchiyama
- National Institute for Basic Biology, National Institutes of Natural Sciences, Aichi, 444-8585, Japan
| | - Yasuhiro Kashino
- Graduate School of Life Science, University of Hyogo, Hyogo, 678-1297, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Naoyuki Miyazaki
- Institute for Protein Research, Osaka University, Osaka, 565-0871, Japan. .,Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Ibaraki, 305-8577, Japan.
| | - Fusamichi Akita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan. .,Japan Science and Technology Agency, PRESTO, Saitama, 332-0012, Japan.
| |
Collapse
|
12
|
Nagao R, Yokono M, Ueno Y, Shen JR, Akimoto S. Excitation-Energy Transfer and Quenching in Diatom PSI-FCPI upon P700 Cation Formation. J Phys Chem B 2020; 124:1481-1486. [DOI: 10.1021/acs.jpcb.0c00715] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Makio Yokono
- Innovation Center, Nippon Flour Mills Company Ltd., Atsugi 243-0041, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| |
Collapse
|
13
|
Kato K, Nagao R, Jiang TY, Ueno Y, Yokono M, Chan SK, Watanabe M, Ikeuchi M, Shen JR, Akimoto S, Miyazaki N, Akita F. Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy. Nat Commun 2019; 10:4929. [PMID: 31666526 PMCID: PMC6821847 DOI: 10.1038/s41467-019-12942-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 10/04/2019] [Indexed: 11/17/2022] Open
Abstract
Photosystem I (PSI) functions to harvest light energy for conversion into chemical energy. The organisation of PSI is variable depending on the species of organism. Here we report the structure of a tetrameric PSI core isolated from a cyanobacterium, Anabaena sp. PCC 7120, analysed by single-particle cryo-electron microscopy (cryo-EM) at 3.3 Å resolution. The PSI tetramer has a C2 symmetry and is organised in a dimer of dimers form. The structure reveals interactions at the dimer-dimer interface and the existence of characteristic pigment orientations and inter-pigment distances within the dimer units that are important for unique excitation energy transfer. In particular, characteristic residues of PsaL are identified to be responsible for the formation of the tetramer. Time-resolved fluorescence analyses showed that the PSI tetramer has an enhanced excitation-energy quenching. These structural and spectroscopic findings provide insights into the physiological significance of the PSI tetramer and evolutionary changes of the PSI organisations.
Collapse
Affiliation(s)
- Koji Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Tian-Yi Jiang
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan
| | - Makio Yokono
- Nippon Flour Mills Co., Ltd., Innovation Center, Kanagawa, 243-0041, Japan
| | - Siu Kit Chan
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Mai Watanabe
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, 153-8902, Japan
| | - Masahiko Ikeuchi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, 153-8902, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan.
| | - Naoyuki Miyazaki
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Japan.
- Institute for Protein Research, Laboratory of Protein Synthesis and Expression, Osaka University, Osaka, 565-0871, Japan.
| | - Fusamichi Akita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
- Japan Science and Technology Agency, PRESTO, Saitama, 332-0012, Japan.
| |
Collapse
|
14
|
Nagao R, Ueno Y, Yokono M, Shen JR, Akimoto S. Effects of excess light energy on excitation-energy dynamics in a pennate diatom Phaeodactylum tricornutum. PHOTOSYNTHESIS RESEARCH 2019; 141:355-365. [PMID: 30993504 DOI: 10.1007/s11120-019-00639-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 04/04/2019] [Indexed: 05/12/2023]
Abstract
Controlling excitation energy flow is a fundamental ability of photosynthetic organisms to keep a better performance of photosynthesis. Among the organisms, diatoms have unique light-harvesting complexes, fucoxanthin chlorophyll (Chl) a/c-binding proteins. We have recently investigated light-adaptation mechanisms of a marine centric diatom, Chaetoceros gracilis, by spectroscopic techniques. However, it remains unclear how pennate diatoms regulate excitation energy under different growth light conditions. Here, we studied light-adaptation mechanisms in a marine pennate diatom Phaeodactylum tricornutum grown at 30 µmol photons m-2 s-1 and further incubated for 24 h either in the dark, or at 30 or 300 µmol photons m-2 s-1 light intensity, by time-resolved fluorescence (TRF) spectroscopy. The high-light incubated cells showed no detectable oxygen-evolving activity of photosystem II, indicating the occurrence of a severe photodamage. The photodamaged cells showed alterations of steady-state absorption and fluorescence spectra and TRF spectra compared with the dark and low-light adapted cells. In particular, excitation-energy quenching is significantly accelerated in the photodamaged cells as shown by mean lifetime analysis of the Chl fluorescence. These spectral changes by the high-light treatment may result from arrangements of pigment-protein complexes to maintain the photosynthetic performance under excess light illumination. These growth-light dependent spectral properties in P. tricornutum are largely different from those in C. gracilis, thus providing insights into the different light-adaptation mechanisms between the pennate and centric diatoms.
Collapse
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Makio Yokono
- Nippon Flour Mills Co., Ltd, Innovation Center, Atsugi, 243-0041, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe, 657-8501, Japan.
| |
Collapse
|
15
|
Nagao R, Yokono M, Ueno Y, Shen JR, Akimoto S. pH-Sensing Machinery of Excitation Energy Transfer in Diatom PSI-FCPI Complexes. J Phys Chem Lett 2019; 10:3531-3535. [PMID: 31192608 DOI: 10.1021/acs.jpclett.9b01314] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Excitation energy-transfer processes in photosynthetic light-harvesting complexes are strongly affected by the surrounding environments of pigments. Here we report on the effects of pH changes on excitation energy dynamics in both diatom photosystem I-fucoxanthin chlorophyll a/ c-binding protein (PSI-FCPI) and PSI core complexes by means of fluorescence spectroscopies. The steady-state fluorescence spectra of the PSI-FCPI showed similar features among three samples at pH 5.0, 6.5, and 8.0. However, fluorescence decay-associated spectra of the pH 5.0- and 8.0-adapted PSI-FCPI within 100 ps exhibit peak shifts to longer and shorter wavelengths, respectively, than the peaks in the pH 6.5 spectra. Because such spectral changes hardly occur in the PSI complexes, the peak shifts at pH 5.0 and 8.0 in the PSI-FCPI can be ascribed to alterations of pigment-pigment and/or pigment-protein interactions around/within FCPI caused by the pH changes. These findings provide novel physical insights into the pH-sensing light-harvesting strategy in diatom PSI-FCPI.
Collapse
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan
| | - Makio Yokono
- Innovation Center , Nippon Flour Mills Co., Ltd. , Atsugi 243-0041 , Japan
| | - Yoshifumi Ueno
- Graduate School of Science , Kobe University , Kobe 657-8501 , Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan
| | - Seiji Akimoto
- Graduate School of Science , Kobe University , Kobe 657-8501 , Japan
| |
Collapse
|
16
|
Büchel C. Light harvesting complexes in chlorophyll c-containing algae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1861:148027. [PMID: 31153887 DOI: 10.1016/j.bbabio.2019.05.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/22/2019] [Accepted: 05/24/2019] [Indexed: 12/30/2022]
Abstract
Besides the so-called 'green lineage' of eukaryotic photosynthetic organisms that include vascular plants, a huge variety of different algal groups exist that also harvest light by means of membrane intrinsic light harvesting proteins (Lhc). The main taxa of these algae are the Cryptophytes, Haptophytes, Dinophytes, Chromeridae and the Heterokonts, the latter including diatoms, brown algae, Xanthophyceae and Eustigmatophyceae amongst others. Despite the similarity in Lhc proteins between vascular plants and these algae, pigmentation is significantly different since no Chl b is bound, but often replaced by Chl c, and a large diversity in carotenoids functioning in light harvesting and/or photoprotection is present. Due to the presence of Chl c in most of the taxa the name 'Chl c-containing organisms' has become common, however, Chl b-less is more precise since some harbour Lhc proteins that only bind one type of Chl, Chl a. In recent years huge progress has been made about the occurrence and function of Lhc in diatoms, so-called fucoxanthin chlorophyll proteins (FCP), where also the first molecular structure became available recently. In addition, especially energy transfer amongst the unusual pigments bound was intensively studied in many of these groups. This review summarises the present knowledge about the molecular structure, the arrangement of the different Lhc in complexes, the excitation energy transfer abilities and the involvement in photoprotection of the different Lhc systems in the so-called Chl c-containing organisms. This article is part of a Special Issue entitled Light harvesting, edited by Dr. Roberta Croce.
Collapse
Affiliation(s)
- Claudia Büchel
- Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt, Germany.
| |
Collapse
|
17
|
Nagao R, Kagatani K, Ueno Y, Shen JR, Akimoto S. Ultrafast Excitation Energy Dynamics in a Diatom Photosystem I-Antenna Complex: A Femtosecond Fluorescence Upconversion Study. J Phys Chem B 2019; 123:2673-2678. [DOI: 10.1021/acs.jpcb.8b12086] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Kohei Kagatani
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| |
Collapse
|