2021/10/21 更新

写真a

ナガオ リョウ
長尾 遼
NAGAO Ryou
所属
異分野基礎科学研究所 講師(特任)
職名
講師(特任)
外部リンク

学位

  • 博士(学術) ( 2012年4月   東京大学 )

研究キーワード

  • 光捕集

  • 生化学

  • 分光学

  • 光合成

  • 構造生物学

  • 光生物

  • 生物学

研究分野

  • ライフサイエンス / 植物分子、生理科学

  • ライフサイエンス / 分子生物学

  • ライフサイエンス / 機能生物化学

  • ライフサイエンス / 生物物理学

  • ライフサイエンス / 構造生物化学

学歴

  • 東京大学大学院   総合文化研究科   広域科学専攻

    2009年4月 - 2012年3月

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  • Institut de Biologie;Ecole Normale Supérieure (IBENS) Centre National de la Recherche Scientifique    

    2010年9月 - 2010年12月

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  • 東京理科大学    

    2007年4月 - 2009年3月

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  • 東京理科大学   理工学部   工業化学科

    2003年4月 - 2007年3月

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経歴

  • 岡山大学   異分野基礎科学研究所   特任講師

    2020年4月 - 現在

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  • 岡山大学 異分野基礎科学研究所   The Research Institute for Interdisciplinary Science   特任助教

    2017年4月 - 2020年3月

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  • 名古屋大学 大学院理学研究科 物質理学専攻   特任助教

    2013年4月 - 2017年3月

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  • 日本大学 文理学部 物理生命システム科学科   助教

    2012年4月 - 2013年3月

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  • 日本学術振興会   特別研究員DC1

    2009年4月 - 2012年3月

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所属学協会

委員歴

  • 第62回日本植物生理学会年会   高校生生物研究発表審査員  

    2021年3月   

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    団体区分:学協会

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  • 第43回生体分子科学討論会   実行委員  

    2016年6月   

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    団体区分:学協会

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論文

  • Structural basis for assembly and function of a diatom photosystem I-light-harvesting supercomplex. 査読 国際誌

    Ryo Nagao, Koji Kato, Kentaro Ifuku, Takehiro Suzuki, Minoru Kumazawa, Ikuo Uchiyama, Yasuhiro Kashino, Naoshi Dohmae, Seiji Akimoto, Jian-Ren Shen, Naoyuki Miyazaki, Fusamichi Akita

    Nature communications   11 ( 1 )   2481 - 2481   2020年5月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    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.

    DOI: 10.1038/s41467-020-16324-3

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  • Structural basis for the adaptation and function of chlorophyll f in photosystem I. 査読 国際誌

    Koji Kato, Toshiyuki Shinoda, Ryo Nagao, Seiji Akimoto, Takehiro Suzuki, Naoshi Dohmae, Min Chen, Suleyman I Allakhverdiev, Jian-Ren Shen, Fusamichi Akita, Naoyuki Miyazaki, Tatsuya Tomo

    Nature communications   11 ( 1 )   238 - 238   2020年1月

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    担当区分:筆頭著者   記述言語:英語  

    Chlorophylls (Chl) play pivotal roles in energy capture, transfer and charge separation in photosynthesis. Among Chls functioning in oxygenic photosynthesis, Chl f is the most red-shifted type first found in a cyanobacterium Halomicronema hongdechloris. The location and function of Chl f in photosystems are not clear. Here we analyzed the high-resolution structures of photosystem I (PSI) core from H. hongdechloris grown under white or far-red light by cryo-electron microscopy. The structure showed that, far-red PSI binds 83 Chl a and 7 Chl f, and Chl f are associated at the periphery of PSI but not in the electron transfer chain. The appearance of Chl f is well correlated with the expression of PSI genes induced under far-red light. These results indicate that Chl f functions to harvest the far-red light and enhance uphill energy transfer, and changes in the gene sequences are essential for the binding of Chl f.

    DOI: 10.1038/s41467-019-13898-5

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  • pH-Sensing Machinery of Excitation Energy Transfer in Diatom PSI-FCPI Complexes. 査読 国際誌

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Jian-Ren Shen, Seiji Akimoto

    The journal of physical chemistry letters   10 ( 13 )   3531 - 3535   2019年7月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    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.

    DOI: 10.1021/acs.jpclett.9b01314

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  • Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy 査読

    Kato, K, Nagao, R, Jiang, T.-Y, Ueno, Y, Yokono, M, Chan, S. K, Watanabe, M, Ikeuchi, M, Shen, J.-R, Akimoto, S, Miyazaki, N, Akita, F

    Nat. Commun.   10   4929   2019年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Structural basis for energy harvesting and dissipation in a diatom PSII-FCPII 査読

    Nagao, R, Kato, K, Suzuki, T, Ifuku, K, Uchiyama, I, Kashino, Y, Dohmae, N, Akimoto, S, Shen, J.-R, Miyazaki, N, Akita, F

    Nat. Plants   5   890 - 901   2019年

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    担当区分:筆頭著者  

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  • Structural implications for a phycobilisome complex from the thermophilic cyanobacterium Thermosynechococcus vulcanus 査読

    Keisuke Kawakami, Ryo Nagao, Yuhei O. Tahara, Tasuku Hamaguchi, Takehiro Suzuki, Naoshi Dohmae, Daisuke Kosumi, Jian-Ren Shen, Makoto Miyata, Koji Yonekura, Nobuo Kamiya

    Biochimica et Biophysica Acta (BBA) - Bioenergetics   1862 ( 9 )   148458 - 148458   2021年9月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.bbabio.2021.148458

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  • Proton and Water Transfer Pathways in the S2 → S3 Transition of the Water-Oxidizing Complex in Photosystem II: Time-Resolved Infrared Analysis of the Effects of D1-N298A Mutation and NO3– Substitution 査読

    Yasutada Okamoto, Yuichiro Shimada, Ryo Nagao, Takumi Noguchi

    The Journal of Physical Chemistry B   125 ( 25 )   6864 - 6873   2021年7月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.jpcb.1c03386

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  • High-light modification of excitation-energy-relaxation processes in the green flagellate Euglena gracilis 査読

    Ryo Nagao, Makio Yokono, Ka-Ho Kato, Yoshifumi Ueno, Jian-Ren Shen, Seiji Akimoto

    Photosynthesis Research   2021年5月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

    DOI: 10.1007/s11120-021-00849-9

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    その他リンク: https://link.springer.com/article/10.1007/s11120-021-00849-9/fulltext.html

  • Molecular organizations and function of iron-stress-induced-A protein family in Anabaena sp. PCC 7120 査読

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Takehiro Suzuki, Koji Kato, Ka-Ho Kato, Naoki Tsuboshita, Tian-Yi Jiang, Naoshi Dohmae, Jian-Ren Shen, Shigeki Ehira, Seiji Akimoto

    Biochimica et Biophysica Acta (BBA) - Bioenergetics   1862 ( 1 )   148327 - 148327   2021年1月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.bbabio.2020.148327

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  • Basic pH-induced modification of excitation-energy dynamics in fucoxanthin chlorophyll a/c-binding proteins isolated from a pinguiophyte, Glossomastix chrysoplasta 査読

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Ka-Ho Kato, Naoki Tsuboshita, Jian-Ren Shen, Seiji Akimoto

    Biochimica et Biophysica Acta (BBA) - Bioenergetics   1862 ( 1 )   148306 - 148306   2021年1月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.bbabio.2020.148306

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  • Enhancement of excitation-energy quenching in fucoxanthin chlorophyll a/c-binding proteins isolated from a diatom Phaeodactylum tricornutum upon excess-light illumination 査読

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Ka-Ho Kato, Naoki Tsuboshita, Jian-Ren Shen, Seiji Akimoto

    Biochim. Biophys. Acta, Bioenerg.   2021年1月

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    担当区分:筆頭著者, 責任著者  

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  • Structure of a cyanobacterial photosystem I surrounded by octadecameric IsiA antenna proteins. 査読 国際誌

    Fusamichi Akita, Ryo Nagao, Koji Kato, Yoshiki Nakajima, Makio Yokono, Yoshifumi Ueno, Takehiro Suzuki, Naoshi Dohmae, Jian-Ren Shen, Seiji Akimoto, Naoyuki Miyazaki

    Communications biology   3 ( 1 )   232 - 232   2020年5月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Iron-stress induced protein A (IsiA) is a chlorophyll-binding membrane-spanning protein in photosynthetic prokaryote cyanobacteria, and is associated with photosystem I (PSI) trimer cores, but its structural and functional significance in light harvesting remains unclear. Here we report a 2.7-Å resolution cryo-electron microscopic structure of a supercomplex between PSI core trimer and IsiA from a thermophilic cyanobacterium Thermosynechococcus vulcanus. The structure showed that 18 IsiA subunits form a closed ring surrounding a PSI trimer core. Detailed arrangement of pigments within the supercomplex, as well as molecular interactions between PSI and IsiA and among IsiAs, were resolved. Time-resolved fluorescence spectra of the PSI-IsiA supercomplex showed clear excitation-energy transfer from IsiA to PSI, strongly indicating that IsiA functions as an energy donor, but not an energy quencher, in the supercomplex. These structural and spectroscopic findings provide important insights into the excitation-energy-transfer and subunit assembly mechanisms in the PSI-IsiA supercomplex.

    DOI: 10.1038/s42003-020-0949-6

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  • Acidic pH-induced modification of energy transfer in diatom fucoxanthin chlorophyll a/c-binding proteins 査読

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Jian-Ren Shen, Seiji Akimoto

    J. Phys. Chem. B   124   4919 - 4923   2020年5月

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    担当区分:筆頭著者, 責任著者   掲載種別:研究論文(学術雑誌)  

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  • pH-Induced Regulation of Excitation Energy Transfer in the Cyanobacterial Photosystem I Tetramer. 査読 国際誌

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Tian-Yi Jiang, Jian-Ren Shen, Seiji Akimoto

    The journal of physical chemistry. B   124 ( 10 )   1949 - 1954   2020年3月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    Excitation energy-transfer processes in pigment-protein complexes in photosynthetic organisms are often changed under different pH conditions. However, it is unclear how the pH changes affect excitation energy relaxations in photosystem I (PSI) cores. In this study, we examined the pH sensitivity of energy dynamics in the PSI tetramer, dimer, and monomer isolated from a cyanobacterium, Anabaena sp. PCC 7120, by means of time-resolved fluorescence spectroscopy. Each PSI was adapted to pH 5.0, 6.5, and 8.0. Fluorescence decay-associated (FDA) spectra of the pH 8.0 PSI dimer and monomer showed positive and negative peaks within 5 ps, whereas the FDA spectra of the PSI tetramer did not show such a 5 ps fluorescence component. Mean lifetimes of the fluorescence at pH 6.5 are shorter in the PSI tetramer than in the PSI dimer and monomer, indicating an accelerated energy quenching in the tetramer. The effects of the acidic and basic pHs on the energy-transfer processes differ significantly among the three types of PSIs, suggesting different pH-sensing sites around pigment molecules in the three PSIs. Based on these results, together with our recent structural finding of the PSI tetramer, we discuss functional implications for the pH-sensing regulation of the excitation energy transfer in the PSI tetramer.

    DOI: 10.1021/acs.jpcb.0c01136

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  • Effects of CO2 and temperature on photosynthetic performance in the diatom Chaetoceros gracilis. 査読 国際誌

    Ryo Nagao, Yoshifumi Ueno, Seiji Akimoto, Jian-Ren Shen

    Photosynthesis research   2020年2月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    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.

    DOI: 10.1007/s11120-020-00729-8

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  • Excitation-Energy Transfer and Quenching in Diatom PSI-FCPI upon P700 Cation Formation. 査読 国際誌

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Jian-Ren Shen, Seiji Akimoto

    The journal of physical chemistry. B   124 ( 8 )   1481 - 1486   2020年2月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    Excitation-energy transfer in photosystem I (PSI) is changed by a cation formation of a special pair chlorophyll P700 in the PSI core; however, it remains unclear how light-harvesting pigment-protein complexes are involved in the P700-related energy-transfer mechanisms. Here, we report effects of the redox changes of P700 on excitation-energy dynamics in diatom PSI-fucoxanthin chlorophyll a/c-binding protein (PSI-FCPI) and PSI core complexes by means of time-resolved fluorescence (TRF) spectroscopy. For the TRF measurements, the PSI-FCPI and PSI were adapted under P700 neutral and cation conditions using chemical reagents. Upon the P700+ formation, fluorescence decay-associated (FDA) spectra constructed from the TRF spectra exhibit a larger fluorescence decay amplitude relative to a fluorescence rise magnitude within 100 ps in each of the PSI-FCPI and PSI. The decay components are shifted to lower wavelengths in each of the P700-cation PSI-FCPI and PSI than in the P700-neutral PSIs. The rapid fluorescence decays upon the P700+ formation are clearly verified by mean lifetimes reconstructed from the FDA spectra. Because the P700-cation PSI does not cause charge-separation reactions, the relatively strong decay components and rapid fluorescence decays observed are likely attributed to excitation-energy quenching. These observations suggest that chlorophylls in PSI and around/within FCPI are involved in the energy-quenching events by the redox changes of P700.

    DOI: 10.1021/acs.jpcb.0c00715

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  • Role of the O4 Channel in Photosynthetic Water Oxidation as Revealed by Fourier Transform Infrared Difference and Time-Resolved Infrared Analysis of the D1-S169A Mutant. 査読 国際誌

    Yuichiro Shimada, Tomomi Kitajima-Ihara, Ryo Nagao, Takumi Noguchi

    The journal of physical chemistry. B   124 ( 8 )   1470 - 1480   2020年2月

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    記述言語:英語  

    Photosynthetic water oxidation takes place at the Mn4CaO5 cluster in photosystem II. Although the atomic structures of its intermediates called S states have recently been reported, the catalytic mechanism of water oxidation has not been well understood. Here, to investigate the involvement of the O4 site of the Mn4CaO5 cluster and a water channel from O4 in the water oxidation reaction, we examined the effects of D1-S169A mutation, which perturbs the interaction of a water molecule hydrogen-bonded with O4, by thermoluminescence (TL), Fourier transform infrared (FTIR) difference, and time-resolved infrared (TRIR) measurements. The observed upshifts of TL peaks and some changes in FTIR spectra upon S169A mutation revealed the perturbations of the redox potential of the Mn4CaO5 cluster and the interactions of the surrounding hydrogen bond network. In contrast, FTIR oscillation patterns and TRIR traces showed only minor effects of the mutation on the efficiencies and kinetics of individual S-state transitions. It was thus concluded that the O4 site plays a role in retaining the redox potential and the structure of the hydrogen bond network, whereas it is unlikely to be directly involved in the catalytic reaction of substrate water except for proton transfer through the O4 water chain.

    DOI: 10.1021/acs.jpcb.9b11946

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  • Changes in excitation relaxation of diatoms in response to fluctuating light, probed by fluorescence spectroscopies. 査読 国際誌

    Miyuki Tanabe, Yoshifumi Ueno, Makio Yokono, Jian-Ren Shen, Ryo Nagao, Seiji Akimoto

    Photosynthesis research   2020年2月

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    担当区分:責任著者   記述言語:英語  

    A marine pennate diatom Phaeodactylum tricornutum (Pt) and a marine centric diatom Chaetoceros gracilis (Cg) possess unique light-harvesting complexes, fucoxanthin chlorophyll a/c-binding proteins (FCPs). FCPs have dual functions: light harvesting in the blue to green regions and quenching of excess energy. So far, excitation dynamics including FCPs have been studied by altering continuous light conditions. In the present study, we examined responses of the diatom cells to fluctuating light (FL) conditions. Excitation dynamics in the cells incubated under the FL conditions were analyzed by time-resolved fluorescence measurements followed by global analysis. As responses common to the Pt and Cg cells, quenching behaviors were observed in photosystem (PS) II with time constants of hundreds of picoseconds. The PSII → PSI energy transfer was modified only in the Pt cells, whereas quenching in FCPs was suggested only in the Cg cells, indicating different strategy for the dissipation of excess energy under the FL conditions.

    DOI: 10.1007/s11120-020-00720-3

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  • Adaptation of light-harvesting and energy-transfer processes of a diatom Chaetoceros gracilis to different light qualities. 査読 国際誌

    Seiji Akimoto, Yoshifumi Ueno, Makio Yokono, Jian-Ren Shen, Ryo Nagao

    Photosynthesis research   2020年1月

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    担当区分:最終著者, 責任著者   記述言語:英語  

    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.

    DOI: 10.1007/s11120-020-00713-2

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  • Adaptation of light-harvesting and energy-transfer processes of a diatom Phaeodactylum tricornutum to different light qualities. 査読 国際誌

    Kumiko Oka, Yoshifumi Ueno, Makio Yokono, Jian-Ren Shen, Ryo Nagao, Seiji Akimoto

    Photosynthesis research   2020年1月

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    担当区分:責任著者   記述言語:英語  

    Fucoxanthin-chlorophyll (Chl) a/c-binding proteins (FCPs) are light-harvesting pigment-protein complexes found in diatoms and brown algae. Due to the characteristic pigments, such as fucoxanthin and Chl c, FCPs can capture light energy in blue-to green regions. A pennate diatom Phaeodactylum tricornutum synthesizes a red-shifted form of FCP under weak or red light, extending a light-absorption ability to longer wavelengths. In the present study, we examined changes in light-harvesting and energy-transfer processes of P. tricornutum cells grown under white- and single-colored light-emitting diodes (LEDs). The red-shifted FCP appears in the cells grown under the green, yellow, and red LEDs, and exhibited a fluorescence peak around 714 nm. Additional energy-transfer pathways are established in the red-shifted FCP; two forms (F713 and F718) of low-energy Chl a work as energy traps at 77 K. Averaged fluorescence lifetimes are prolonged in the cells grown under the yellow and red LEDs, whereas they are shortened in the blue-LED-grown cells. Based on these results, we discussed the light-adaptation machinery of P. tricornutum cells involved in the red-shifted FCP.

    DOI: 10.1007/s11120-020-00714-1

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  • Fourier transform infrared and mass spectrometry analyses of a site-directed mutant of D1-Asp170 as a ligand to the water-oxidizing Mn4CaO5 cluster in photosystem II 査読

    Kitajima-Ihara, T, Suzuki, T, Nakamura, S, Shimada, Y, Nagao, R, Dohmae, N, Noguchi, T

    Biochim. Biophys. Acta, Bioenerg.   1861 ( 1 )   148086 - 148086   2020年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.bbabio.2019.148086

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  • Does the water-oxidizing Mn4CaO5 cluster regulate the redox potential of the primary quinone electron acceptor QA in photosystem II? A study by Fourier transform infrared spectroelectrochemistry 査読

    Kato, Y, Ohira, A, Nagao, R, Noguchi, T

    Biochim. Biophys. Acta, Bioenerg.   1860   148082   2019年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Effects of excess light energy on excitation-energy dynamics in a pennate diatom Phaeodactylum tricornutum. 査読 国際誌

    Ryo Nagao, Yoshifumi Ueno, Makio Yokono, Jian-Ren Shen, Seiji Akimoto

    Photosynthesis research   141 ( 3 )   355 - 365   2019年9月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    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.

    DOI: 10.1007/s11120-019-00639-4

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  • Biochemical characterization of photosystem I complexes having different subunit compositions of fucoxanthin chlorophyll a/c-binding proteins in the diatom Chaetoceros gracilis. 査読 国際誌

    Ryo Nagao, Yoshifumi Ueno, Fusamichi Akita, Takehiro Suzuki, Naoshi Dohmae, Seiji Akimoto, Jian-Ren Shen

    Photosynthesis research   140 ( 2 )   141 - 149   2019年5月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    Diatoms are dominant phytoplankton in aquatic environments and have unique light-harvesting apparatus, fucoxanthin chlorophyll a/c-binding protein (FCP). Diatom photosystem I (PSI) interacts with specific FCPs (FCPI); however, it remains unclear how PSI cores receive excitation energy from FCPI. To analyze the energy transfer dynamics, it is necessary to isolate both PSI cores and PSI-FCPI complexes. In this study, we prepared three PSI complexes, which are PSI-FCPI membrane fragments, detergent-solubilized PSI-FCPI supercomplexes and PSI core-like complexes, from the marine centric diatom, Chaetoceros gracilis, and examined their biochemical properties. Both the PSI-FCPI membrane fragments and supercomplexes showed similar subunit compositions including FCPI, whereas the PSI complexes were devoid of most FCPI subunits. The purity and homogeneity of the two detergent-solubilized PSI preparations were verified by clear-native PAGE and electron microscopy. The difference of pigment contents among the three PSI samples was shown by absorption spectra at 77 K. The intensity in the whole spectrum of PSI-FCPI membranes was much higher than those of the other two complexes, while the spectral shape of PSI complexes was similar to that of cyanobacterial PSI core complexes. 77-K fluorescence spectra of the three PSI preparations exhibited different spectral shapes, especially peak positions and band widths. Based on these observations, we discuss the merits of three PSI preparations for evaluating excitation energy dynamics in diatom PSI-FCPI complexes.

    DOI: 10.1007/s11120-018-0576-y

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  • Ultrafast Excitation Energy Dynamics in a Diatom Photosystem I-Antenna Complex: A Femtosecond Fluorescence Upconversion Study. 査読 国際誌

    Ryo Nagao, Kohei Kagatani, Yoshifumi Ueno, Jian-Ren Shen, Seiji Akimoto

    The journal of physical chemistry. B   123 ( 12 )   2673 - 2678   2019年3月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    Fucoxanthin chlorophyll (Chl) a/ c-binding proteins (FCPs) are unique light-harvesting antennas in diatoms. Recent time-resolved fluorescence analysis of photosystem I with FCP associated (PSI-FCPI) has mainly shown excitation energy transfer among Chls a from FCPI to PSI in tens of picoseconds. However, it remains unclear how each pigment, especially carotenoids and Chl c, in the FCPI is functionally related to the energy transfer in a femtosecond time range. Here, we reveal ultrafast excitation energy transfer mechanism in the PSI-FCPI preparations isolated from a diatom, Chaetoceros gracilis, by means of femtosecond time-resolved fluorescence spectroscopy with an upconversion system. Compared with the fluorescence lifetime components of PSI core-like complexes, the energy transfer of Chl c → Chl a in the FCPI was observed within hundreds of femtoseconds, and the energy in the FCPI was transferred to PSI in ∼2 ps. The comparative fluorescence analyses provide physical insights into the energy transfer machinery within FCPI and from FCPI to PSI.

    DOI: 10.1021/acs.jpcb.8b12086

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  • Low-Energy Chlorophylls in Fucoxanthin Chlorophyll a/ c-Binding Protein Conduct Excitation Energy Transfer to Photosystem I in Diatoms. 査読 国際誌

    Ryo Nagao, Makio Yokono, Yoshifumi Ueno, Jian-Ren Shen, Seiji Akimoto

    The journal of physical chemistry. B   123 ( 1 )   66 - 70   2019年1月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    Photosynthetic organisms handle solar energy precisely to achieve efficient photochemical reactions. Because there are a wide variety of light-harvesting antennas in oxyphototrophs, the excitation energy transfer mechanisms are thought to differ significantly. In this study, we compared excitation energy dynamics between photosystem I (PSI) cores and a complex between PSI and fucoxanthin chlorophyll (Chl) a/ c-binding protein I (PSI-FCPI) isolated from a diatom, Chaetoceros gracilis, by means of picosecond time-resolved fluorescence analyses. Time-resolved spectra measured at 77 K clearly show that low-energy Chls in the FCPI transfer not only most of the excitation energy to the reaction center Chls in the PSI cores but also the remaining energy to carotenoids for quenching. Under room-temperature conditions, the energy in the low-energy Chls is rapidly equilibrated on Chls in the PSI cores by uphill energy transfer within a few tens of picoseconds. These findings provide solid evidence that the low-energy Chls in the FCPI contribute to the photochemical reactions in PSI.

    DOI: 10.1021/acs.jpcb.8b09253

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  • Spectral properties and excitation relaxation of novel fucoxanthin chlorophyll a/c-binding protein complexes 査読

    Ueno, Y, Nagao, R, Shen, J.-R, Akimoto, S

    J. Phys. Chem. Lett.   10   5148 - 5152   2019年

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Redox-state dependent blinking of single photosystem I trimers at around liquid-nitrogen temperature 査読

    Jana, S, Du, T, Nagao, R, Noguchi, T, Shibata, Y

    Biochim. Biophys. Acta, Bioenerg.   1860   30 - 40   2019年

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    記述言語:英語  

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  • Alterations of pigment composition and their interactions in response to different light conditions in the diatom Chaetoceros gracilis probed by time-resolved fluorescence spectroscopy. 査読 国際誌

    Ryo Nagao, Yoshifumi Ueno, Makio Yokono, Jian-Ren Shen, Seiji Akimoto

    Biochimica et biophysica acta. Bioenergetics   1859 ( 7 )   524 - 530   2018年7月

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    担当区分:筆頭著者, 責任著者   記述言語:英語  

    Maintenance of energy balance under changeable light conditions is an essential function of photosynthetic organisms to achieve efficient photochemical reactions. Among the photosynthetic organisms, diatoms possess light-harvesting fucoxanthin chlorophyll (Chl) a/c-binding protein (FCP) as peripheral antennas. However, how diatoms regulate excitation-energy distribution between FCP and the two photosystem cores during light adaptation is poorly understood. In this study, we examined spectroscopic properties of a marine diatom Chaetoceros gracilis adapted in the dark and at photosynthetic photon flux density at 30 and 300 μmol photons m-2 s-1. Absorption spectra at 77 K showed significant changes in the Soret region, and 77-K steady-state fluorescence spectra showed significant differences in the spectral shape and relative fluorescence intensity originating from both PSII and PSI, among the cells grown under different light conditions. These results suggest alterations of pigment composition and their interactions under the different light conditions. These alterations affected the excitation-energy dynamics monitored by picosecond time-resolved fluorescence analyses at 77 K significantly. The contributions of Chls having lower energy levels than the reaction center Chls in the two photosystems to the energy dynamics were clearly identified in the three cells but with presumably different roles. These findings provide insights into the regulatory mechanism of excitation-energy balance in diatoms under various light conditions.

    DOI: 10.1016/j.bbabio.2018.04.003

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  • Evaluation of photosynthetic activities in thylakoid membranes by means of Fourier transform infrared spectroscopy 査読

    Ryo Nagao, Sho Kitazaki, Takumi Noguchi

    Biochimica et Biophysica Acta - Bioenergetics   1859 ( 2 )   129 - 136   2018年2月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier B.V.  

    Light-induced Fourier transformed infrared (FTIR) difference spectroscopy is a powerful method to study the structures and reactions of redox cofactors involved in the photosynthetic electron transport chain. So far, most of the FTIR studies of the reactions of oxygenic photosynthesis have been performed using isolated photosystem I (PSI) and photosystem II (PSII) preparations, which, however, could be modified during isolation procedures. In this study, we developed a methodology to evaluate the photosynthetic activities of thylakoids using FTIR spectroscopy. FTIR difference spectra upon successive flashes using thylakoids from spinach exhibited signals typical of the S-state cycle at the Mn4CaO5 cluster and QB reactions in PSII with period-four and -two oscillations, respectively. Similar measurement in the presence of an artificial quinone as an exogenous electron acceptor showed features specific to the S-state cycle. Simulations of the oscillation patterns provided the quantum efficiencies of the S-state cycle and electron transfer in PSII. Moreover, FTIR measurement under continuous illumination on thylakoids in the presence of DCMU showed signals due to QA reduction and P700 oxidation simultaneously. From the relative amplitudes of marker bands of QA − and P700+, the molar ratio of photoactive PSII and PSI centers in thylakoids was estimated. FTIR analyses of the photo-reactions in thylakoids, which are more intact than isolated photosystems, will be useful in investigations of the photosynthetic mechanism especially by genetic modification of photosystem proteins.

    DOI: 10.1016/j.bbabio.2017.11.004

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  • Thylakoid membrane lipid sulfoquinovosyl-diacylglycerol (SQDG) is required for full functioning of photosystem II in Thermosynechococcus elongatus 査読

    Nakajima, Y, Umena, Y, Nagao, R, Endo, K, Kobayashi, K, Akita, F, Suga, M, Wada, H, Noguchi, T, Shen, J.-R

    J. Biol. Chem.   293   14786 - 14797   2018年

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  • The PsbQ′ protein affects the redox potential of the QA in photosystem II 査読

    Yamada, M, Nagao, R, Iwai, M, Arai, Y, Makita, A, Ohta, H, Tomo, T

    Photosynthetica   56   185 - 191   2018年

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  • Lysyl oxidase‐like protein secreted from an acidophilic red alga, Cyanidium caldarium 査読

    Tomo, T, Okumura, A, Suzuki, T, Okuhara, M, Katayama, R, Isayama, N, Nagao, R, Iwai, M, Dohmae, N, Enami, I

    Plant Direct   2   1 - 10   2018年

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  • D1-Asn-298 in photosystem II is involved in a hydrogen-bond network near the redox-active tyrosine Y-Z for proton exit during water oxidation 査読

    Ryo Nagao, Hanayo Ueoka-Nakanishi, Takumi Noguchi

    JOURNAL OF BIOLOGICAL CHEMISTRY   292 ( 49 )   20046 - 20057   2017年12月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

    In photosynthetic water oxidation, two water molecules are converted into one oxygen molecule and four protons at the Mn4CaO5 cluster in photosystem II (PSII) via the S-state cycle. Efficient proton exit from the catalytic site to the lumen is essential for this process. However, the exit pathways of individual protons through the PSII proteins remain to be identified. In this study, we examined the involvement of a hydrogen-bond network near the redox-active tyrosine Y-Z in proton transfer during the S-state cycle. We focused on spectroscopic analyses of a site-directed variant of D1-Asn-298, a residue involved in a hydrogen-bond network near Y-Z. We found that the D1-N298A mutant of Synechocystis sp. PCC 6803 exhibits an O-2 evolution activity of approximate to 10% of the wild-type. D1-N298A and the wild-type D1 had very similar features of thermoluminescence glow curves and of an FTIR difference spectrum upon Y-Z oxidation, suggesting that the hydrogen-bonded structure of Y-Z and electron transfer from the Mn4CaO5 cluster to Y-Z were little affected by substitution. In the D1-N298A mutant, however, the flash-number dependence of delayed luminescence showed a monotonic increase without oscillation, and FTIR difference spectra of the S-state cycle indicated partial and significant inhibition of the S-2 S-3 and S-3 S-0 transitions, respectively. These results suggest that the D1-N298A substitution inhibits the proton transfer processes in the S-2 S-3 and S-3 S-0 transitions. This in turn indicates that the hydrogen-bond network near Y-Z can be functional as a proton transfer pathway during photosynthetic water oxidation.

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  • Functional role of Lys residues of Psb31 in electrostatic interactions with diatom photosystem II 査読

    Ryo Nagao, Takehiro Suzuki, Naoshi Dohmae, Jian-Ren Shen, Tatsuya Tomo

    FEBS Letters   591 ( 20 )   3259 - 3264   2017年10月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   出版者・発行元:Wiley Blackwell  

    We recently revealed that positively charged amino acids of Psb31, an extrinsic subunit found in diatom photosystem II (PSII), are involved in electrostatic interactions with PSII intrinsic subunits. However, the molecular interactions of Psb31 with PSII remain unclear. Here, we report the functional contribution of Lys residues in the binding of Psb31 to PSII using site-directed mutants of Psb31. Each of the K33A, K39A, K54A, K56A, K57A, and K69A mutants exhibits decreased binding affinities to PSII concomitantly with decreases in the O2 evolution activity. Conversely, each of the K24A, K76A, K80A, and K117A mutants functionally binds to PSII in a manner similar to wild-type Psb31. These results provide evidence that some Lys residues of Psb31 are responsible for electrostatic interactions with PSII.

    DOI: 10.1002/1873-3468.12830

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  • Electrostatic interaction of positive charges on the surface of Psb31 with photosystem II in the diatom Chaetoceros gracilis 査読

    Ryo Nagao, Takehiro Suzuki, Akinori Okumura, Tomohiro Kihira, Ayaka Toda, Naoshi Dohmae, Katsuyoshi Nakazato, Tatsuya Tomo

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1858 ( 9 )   779 - 785   2017年9月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Psb31, a novel extrinsic protein found in diatom photosystem II (PSII), directly binds to PSII core subunits, independent of the other extrinsic proteins, and functions to maintain optimum oxygen evolution. However, how Psb31 electrostatically interacts with PSII intrinsic proteins remains to be clarified. In this study, we examined electrostatic interaction of Psb31 with PSII complexes isolated from the diatom Chaetoceros gracilis. Positive or negative charges of isolated Psb31 proteins were modified with N-succinimidyl propionate (NSP) or glycine methyl ester (GME), respectively, resulting in formation of uncharged groups. NSP-modified Psb31 did not bind to PSII with a concomitant increase in NSP concentration, whereas GME-modified Psb31 clearly bound to PSII with retention of oxygen-evolving activity, indicating that positive charges of Lys residues and the N-terminus on the surface of Psb31 are involved in electrostatic interactions with PSII intrinsic proteins. Mass spectrometry analysis of NSP-modified Psb31 and sequence comparisons of Psb31 from C. gracilis with other chromophyte algae led to identification of three Lys residues as possible binding sites to PSII. Based on these findings, together with our previous cross-linking study in diatom PSII and a red algal PSII structure, we discuss binding properties of Psb31 with PSII core proteins.

    DOI: 10.1016/j.bbabio.2017.06.002

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  • Fluorescence property of photosystem II protein complexes bound to a gold nanoparticle 査読

    Kazuki Tahara, Ahmed Mohamed, Kousuke Kawahara, Ryo Nagao, Yuki Kato, Hiroshi Fukumura, Yutaka Shibata, Takumi Noguchi

    FARADAY DISCUSSIONS   198   121 - 134   2017年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Development of an efficient photo-anode system for water oxidation is key to the success of artificial photosynthesis. We previously assembled photosystem II (PSII) proteins, which are an efficient natural photocatalyst for water oxidation, on a gold nanoparticle (GNP) to prepare a PSII-GNP conjugate as an anode system in a light-driven water-splitting nanodevice (Noji et al., J. Phys. Chem. Lett., 2011, 2, 2448-2452). In the current study, we characterized the fluorescence property of the PSII-GNP conjugate by static and time-resolved fluorescence measurements, and compared with that of free PSII proteins. It was shown that in a static fluorescence spectrum measured at 77 K, the amplitude of a major peak at 683 nm was significantly reduced and a red shoulder at 693 nm disappeared in PSII-GNP. Time-resolved fluorescence measurements showed that picosecond components at 683 nm decayed faster by factors of 1.4-2.1 in PSII-GNP than in free PSII, explaining the observed quenching of the major fluorescence peak. In addition, a nanosecond-decay component arising from a 'red chlorophyll' at 693 nm was lost in time-resolved fluorescence of PSII-GNP, probably due to a structural perturbation of this chlorophyll by interaction with GNP. Consistently with these fluorescence properties, degradation of PSII during strong-light illumination was two times slower in PSII-GNP than in free PSII. The enhanced durability of PSII is an advantageous property of the PSII-GNP conjugate in the development of an artificial photosynthesis device.

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  • Genetically introduced hydrogen bond interactions reveal an asymmetric charge distribution on the radical cation of the special-pair chlorophyll P680 査読

    Ryo Nagao, Motoki Yamaguchi, Shin Nakamura, Hanayo Ueoka-Nakanishi, Takumi Noguchi

    JOURNAL OF BIOLOGICAL CHEMISTRY   292 ( 18 )   7474 - 7486   2017年5月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

    The special-pair chlorophyll (Chl) P680 in photosystem II has an extremely high redox potential (E-m) to enable water oxidation in photosynthesis. Significant positive-charge localization on one of the Chl constituents, P-D1 or P-D2, in P680(+) has been proposed to contribute to this high E-m. To identify the Chl molecule on which the charge is mainly localized, we genetically introduced a hydrogen bond to the 13(1)-keto C=O group of P-D1 and P-D2 by changing the nearby D1-Val-157 and D2-Val-156 residues to His, respectively. Successful hydrogen bond formation at P-D1 and P-D2 in the obtained D1-V157H and D2-V156H mutants, respectively, was monitored by detecting 13(1)-keto C=O vibrations in Fourier transfer infrared (FTIR) difference spectra upon oxidation of P680 and the symmetrically located redox-active tyrosines Y-Z and Y-D, and they were simulated by quantum-chemical calculations. Analysis of the P680(+)/P680 FTIR difference spectra of D1-V157H and D2-V156H showed that upon P680(+) formation, the 13(1)-keto C=O frequency upshifts by a much larger extent in P-D1 (23 cm(-1)) than in P-D2 (<9 cm(-1)). In addition, thermoluminescence measurements revealed that the D1-V157H mutation increased the E-m of P680 to a larger extent than did the D2-V156H mutation. These results, together with the previous results for the mutants of the His ligands of P-D1 and P-D2, lead to a definite conclusion that a charge is mainly localized to P-D1 in P680(+).

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  • Monitoring the reaction process during the S2 → S3 transition in photosynthetic water oxidation using time-resolved infrared spectroscopy 査読

    Sakamoto, H, Shimizu, T, Nagao, R, Noguchi, T

    J. Am. Chem. Soc.   139 ( 5 )   2022 - 2029   2017年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Conversion of photosystem II dimer to monomers during photoinhibition is tightly coupled with decrease in oxygen-evolving activity in the diatom Chaetoceros gracilis 査読

    Ryo Nagao, Tatsuya Tomo, Rei Narikawa, Isao Enami, Masahiko Ikeuchi

    PHOTOSYNTHESIS RESEARCH   130 ( 1-3 )   83 - 91   2016年12月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The rapid turnover of photosystem II (PSII) in diatoms is thought to be at an exceptionally high rate compared with other oxyphototrophs; however, its molecular mechanisms are largely unknown. In this study, we examined the photodamage and repair processes of PSII in the marine centric diatom Chaetoceros gracilis incubated at 30 or 300 mu mol photons m(-2) s(-1) in the presence of a de novo protein-synthesis inhibitor. When de novo protein synthesis was blocked by chloramphenicol (Cm), oxygen-evolving activity gradually decreased even at 30 mu mol photons m(-2) s(-1) and could not be detected at 12 h. PSII inactivation was enhanced by higher illumination. Using Cm-treated cells, the conversion of PSII dimer to monomers was observed by blue native PAGE. The rate of PSII monomerization was very similar to that of the decrease in oxygen-evolving activity under both light conditions. Immunological detection of D1 protein in the Cm-treated cells showed that the rate of D1 degradation was slower than that of the former two events, although it was more rapid than that observed in other oxyphototrophs. Thus, the three accelerated events, especially PSII monomerization, appear to cause the unusually high rate of PSII turnover in diatoms.

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  • The N-terminal sequence of the extrinsic PsbP protein modulates the redox potential of Cyt b(559) in photosystem II 査読

    Taishi Nishimura, Ryo Nagao, Takumi Noguchi, Jon Nield, Fumihiko Sato, Kentaro Ifuku

    SCIENTIFIC REPORTS   6   21490   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATURE PUBLISHING GROUP  

    The PsbP protein, an extrinsic subunit of photosystem II (PSII) in green plants, is known to induce a conformational change around the catalytic Mn4CaO5 cluster securing the binding of Ca2+ and Cl- in PSII. PsbP has multiple interactions with the membrane subunits of PSII, but how these affect the structure and function of PSII requires clarification. Here, we focus on the interactions between the N-terminal residues of PsbP and the a subunit of Cytochrome (Cyt) b(559) (PsbE). A key observation was that a peptide fragment formed of the first N-terminal 15 residues of PsbP, 'pN15', was able to convert Cyt b(559) into its HP form. Interestingly, addition of pN15 to NaCl-washed PSII membranes decreased PSII's oxygen-evolving activity, even in the presence of saturating Ca2+ and Cl- ions. In fact, pN15 reversibly inhibited the S-1 to S-2 transition of the OEC in PSII. These data suggest that pN15 can modulate the redox property of Cyt b(559) involved in the side-electron pathway in PSII. This potential change of Cyt b559, in the absence of the C-terminal domain of PsbP, however, would interfere with any electron donation from the Mn4CaO5 cluster, leading to the possibility that multiple interactions of PsbP, binding to PSII, have distinct roles in regulating electron transfer within PSII.

    DOI: 10.1038/srep21490

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  • Redox potential of the terminal quinone electron acceptor Q(B) in photosystem II reveals the mechanism of electron transfer regulation 査読

    Yuki Kato, Ryo Nagao, Takumi Noguchi

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   113 ( 3 )   620 - 625   2016年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATL ACAD SCIENCES  

    Photosystem II (PSII) extracts electrons from water at a Mn4CaO5 cluster using light energy and then transfers them to two plastoquinones, the primary quinone electron acceptor Q(A) and the secondary quinone electron acceptor Q(B). This forward electron transfer is an essential process in light energy conversion. Meanwhile, backward electron transfer is also significant in photoprotection of PSII proteins. Modulation of the redox potential (E-m) gap of Q(A) and Q(B) mainly regulates the forward and backward electron transfers in PSII. However, the full scheme of electron transfer regulation remains unresolved due to the unknown E-m value of Q(B). Here, for the first time (to our knowledge), the E-m value of QB reduction was measured directly using spectroelectrochemistry in combination with light-induced Fourier transform infrared difference spectroscopy. The E-m(Q(B)(-)/Q(B)) was determined to be approximately +90 mV and was virtually unaffected by depletion of the Mn4CaO5 cluster. This insensitivity of E-m(Q(B)(-)/Q(B)), in combination with the known large upshift of E-m(Q(A)(-)/Q(A)), explains the mechanism of PSII photoprotection with an impaired Mn4CaO5 cluster, in which a large decrease in the E-m gap between Q(A) and Q(B) promotes rapid charge recombination via Q(A)(-).

    DOI: 10.1073/pnas.1520211113

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  • Structure-Based Modeling of Fluorescence Kinetics of Photosystem II: Relation between Its Dimeric Form and Photoregulation 査読

    Ahmed Mohamed, Ryo Nagao, Takumi Noguchi, Hiroshi Fukumura, Yutaka Shibata

    JOURNAL OF PHYSICAL CHEMISTRY B   120 ( 3 )   365 - 376   2016年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A photosystem II.-enriched membrane (PSII-em) consists of the PSII core complex (PSII-cc) which is surrounded by peripheral antenna complexes. PSII-cc consists of two,cote antenna (CP43 and CP47) and the reaction center (RC) complex. Time-resolved fluorescence spectra of a PSII-ern were measured at 77 K. The data were-globally analyzed with a new compartment model, which has a minimum number of compartments and is consistent with the Structure of PSII-cc. The reliability of the model was investigated by fitting the data Of different,experimental-conditions. From the analysis, the energy-transfer time constants from the peripheral antenna to, CP47 and CP43 were estimated to be 20 and 35 ps, respectively With an exponential time constant of 320 ps, the excitation energy was estimated to accumulate in the reddest chlorophyll (Red Chl), giving,a 692 nm fluorescence peak. The excited state on the Red Chl was confirmed to be quenched upon the addition of an oxidant, as reported previously. The calculations based on the Forster theory predicted that the excitation energy on Chl29 is quenched by Chl(ZD1)(+), which is a redox active but not involved in the electron-transfer chain, located in the D1 subunit of,RC, in the other monomer with an exponential time constant of 75 ps. This quenching pathway is consistent with our structure-based simulation of PSII-cc, which assigned Chl29 as the Red Chl. On the other hand, the alternative interpretation assigning Chl26 as the Red Chl was not excluded. The excited Chl26 was predicted to be quenched by another redox active Chl(ZD2)(+) in the D2 subunit of RC in the same monomer unit with an exponential time constant of 88 ps.

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  • Regulation of excitation energy transfer in diatom PSII dimer: How does it change the destination of excitation energy? 査読

    Makio Yokono, Ryo Nagao, Tatsuya Tomo, Seiji Akimoto

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1847 ( 10 )   1274 - 1282   2015年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Energy transfer dynamics in dimeric photosystem II (PSII) complexes isolated from four diatoms, Chaetoceros gracilis, Cyclotella meneghiniana, Thalassiosira pseudonana, and Phaeodactylum tricornutum, are examined. Time-resolved fluorescence measurements were conducted in the range of 0-80 ns. Delayed fluorescence spectra showed a clear difference between PSII monomer and PSII dimer isolated from the four diatoms. The difference can be interpreted as reflecting suppressed energy transfer between PSII monomers in the PSII dimer for efficient energy trapping at the reaction center. The observation was especially prominent in C gracilis and T. pseudonana. The pathways seem to be suppressed under a low pH condition in isolated PSII complexes from C. gracilis, and excitation energy may be quenched with fucoxanthin chlorophyll a/c-binding protein (FCP) that was closely associated with PSII in C gracilis. The energy transfer between PSII monomers in the PSII dimer may play a role in excitation energy regulation in diatoms. (C) 2015 Elsevier B.V. All rights reserved.

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  • Effects of Extrinsic Proteins on the Protein Conformation of the Oxygen-Evolving Center in Cyanobacterial Photosystem II As Revealed by Fourier Transform Infrared Spectroscopy 査読

    Ryo Nagao, Tatsuya Tomo, Takumi Noguchi

    BIOCHEMISTRY   54 ( 11 )   2022 - 2031   2015年3月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Extrinsic proteins of photosystem II (PSII) play an important role in optimizing oxygen-evolving reactions in all oxyphototrophs. The currently available crystal structures of cyanobacterial PSII core complexes show the binding structures of the extrinsic proteins, PsbO, PsbV, and PsbU; however, how the individual extrinsic proteins affect the structure and the function of the oxygen-evolving center (OEC) in cyanobacterial PSII remains unknown. In this study, we have investigated the effects of the binding of the extrinsic proteins on the protein conformation of the OEC in PSII core complexes from the thermophilic cyanobacterium Thermosynechococcus elongatus, using light-induced Fourier transform infrared (FTIR) difference spectroscopy. Upon removal of the three extrinsic proteins, an S-2-minus-S-1 FTIR difference spectrum measured in the presence of a high CaCl2 concentration showed a drastic change in amide I bands, reflecting perturbation of the secondary structures of polypeptides, whereas the overall spectral intensity was lost at a low CaCl2 concentration, indicative of inactivation of the Mn4CaO5 cluster. The amide I features as well as the overall intensity were recovered mainly by binding of PsbO, while complete amide I recovery was achieved by further binding of PsbV and PsbU. We thus concluded that PsbO, together with smaller contributions of PsbV and PsbU, plays a role in the maintenance of the proper protein conformation of the OEC in cyanobacterial PSII, which provides the stability of the Mn4CaO5 cluster via the enhanced retention capability of Ca2+ and Cl- ions.

    DOI: 10.1021/acs.biochem.5b00053

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  • Control Mechanism of Excitation Energy Transfer in a Complex Consisting of Photosystem II and Fucoxanthin Chlorophyll a/c-Binding Protein 査読

    Ryo Nagao, Makio Yokono, Tatsuya Tomo, Seiji Akimoto

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   5 ( 17 )   2983 - 2987   2014年9月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Fucoxanthin chlorophyll (Chi) a/c-binding protein (FCP) is a unique light-harvesting antenna in diatoms, which are photosynthesizing algae ubiquitous in aquatic environments. However, it is unknown how excitation energy is trapped and quenched in a complex consisting of photosystem II and FCP (PSII FCPII complex). Here, we report the control mechanism of excitation energy transfer in the PSII-FCPII complexes isolated from a diatom, Chaetoceros gracilis, as revealed by picosecond time-resolved fluorescence spectroscopy. The results showed that Chl-excitation energy is harvested in low-energy Chls near/within FCPII under the 77 K conditions, whereas most of the energy is trapped in reaction center Chls in PSII under the 283 K conditions. Surprisingly, excitation energy quenching was observed in a part of PSII-FCPII complexes with the time constants of hundreds of picosecond, thus indicating the large contribution of FCPII to energy trapping and quenching. On the basis of these results, we discuss the light-harvesting strategy of diatoms.

    DOI: 10.1021/jz501496p

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  • Excitation relaxation dynamics and energy transfer in fucoxanthin-chlorophyll a/c-protein complexes, probed by time-resolved fluorescence 査読

    Seiji Akimoto, Ayaka Teshigahara, Makio Yokono, Mamoru Mimuro, Ryo Nagao, Tatsuya Tomo

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1837 ( 9 )   1514 - 1521   2014年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    In algae, light-harvesting complexes contain specific chlorophylls (Chls) and keto-carotenoids; Chl a, Chl c, and fucoxanthin (Fx) in diatoms and brown algae; Chl a, Chl c, and peridinin in photosynthetic dinoflagellates; and Chl a, Chl b, and siphonaxanthin in green algae. The Fx-Chl a/c-protein (FCP) complex from the diatom Chaetoceros gracilis contains Chl c(1), Chl c(2), and the keto-carotenoid, Fx, as antenna pigments, in addition to Chl a. In the present study, we investigated energy transfer in the FCP complex associated with photosystem II (FCPII) of C. gracilis. For these investigations, we analyzed time-resolved fluorescence spectra, fluorescence rise and decay curves, and time-resolved fluorescence anisotropy data. Chl a exhibited different energy forms with fluorescence peaks ranging from 677 nm to 688 nm. Fx transferred excitation energy to lower-energy Chl a with a time constant of 300 fs. Chl c transferred excitation energy to Chl a with time constants of 500-600 fs (intra-complex transfer), 600-700 fs (intra-complex transfer), and 4-6 ps (inter-complex transfer). The latter process made a greater contribution to total Chl c-to-Chl a transfer in intact cells of C. gracilis than in the isolated FCPII complexes. The lower-energy Chl a received excitation energy from Fx and transferred the energy to higher-energy Chl a. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: Keys to Produce Clean Energy. (C) 2014 Published by Elsevier B.V.

    DOI: 10.1016/j.bbabio.2014.02.002

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  • Identification of the basic amino acid residues on the PsbP protein involved in the electrostatic interaction with photosystem II 査読

    Nishimura, T, Uno, C, Ido, K, Nagao, R, Noguchi, T, Sato, F, Ifuku, K

    Biochim. Biophys. Acta, Bioenerg.   1837 ( 9 )   1447 - 1453   2014年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.bbabio.2013.12.012

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  • Light-Harvesting Ability of the Fucoxanthin Chlorophyll a/c-Binding Protein Associated with Photosystem II from the Diatom Chaetoceros gracilis As Revealed by Picosecond Time-Resolved Fluorescence Spectroscopy 査読

    Ryo Nagao, Makio Yokono, Ayaka Teshigahara, Seiji Akimoto, Tatsuya Tomo

    JOURNAL OF PHYSICAL CHEMISTRY B   118 ( 19 )   5093 - 5100   2014年5月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The fucoxanthin chlorophyll a/c-binding protein (FCP) is a unique antenna complex possessed by diatoms. Although FCP complexes have been isolated from various diatoms, there is no direct evidence for the existence of FCP associated with photosystem II (FCPII). Here, we report the isolation and spectroscopic characterization of FCPII complex from the diatom Chaetoceros gracilis. The FCPII complex was purified using sucrose centrifugation and anion-exchange chromatography. Clear-native PAGE and SDS-PAGE analyses revealed that the FCPII complex was composed of FCP-A oligomer and FCP-B/C trimer. Time-resolved fluorescence spectra of the FCPII complex were measured at 77 K. The characteristic lifetimes and fluorescence components were determined using global fitting analysis, followed by the construction of fluorescence decay-associated spectra (FDAS). FDAS exhibited fluorescence rises and decays, reflecting excitation energy transfer, with the time constants of 150 ps, 800 ps, and 2.9 ns. The long time constants are most likely attributed to the intercomplex excitation energy transfer between FCP-A oligomer and FCP-B/C trimer in the FCPII complex. The 5.6 ns FDAS likely originates from the final energy traps. In contrast, the FDAS exhibited no quenching component with any time constant. These results indicate that the FCPII complex is efficient in light harvesting and excitation energy transfer.

    DOI: 10.1021/jp502035y

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  • Fourier Transform Infrared Detection of a Polarizable Proton Trapped between Photooxidized Tyrosine Y-z and a Coupled Histidine in Photosystem II: Relevance to the Proton Transfer Mechanism of Water Oxidation 査読

    Shin Nakamura, Ryo Nagao, Ryouta Takahashi, Takumi Noguchi

    BIOCHEMISTRY   53 ( 19 )   3131 - 3144   2014年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The redox-active tyrosine Y-Z (D1-Tyr161) in photosystem II (PSII) functions as an immediate electron acceptor of the Mn4Ca cluster, which is the catalytic center of photosynthetic water oxidation. Y-Z is also located in the hydrogen bond network that connects the Mn4Ca cluster to the lumen and hence is possibly related to the proton transfer process during water oxidation. To understand the role of Y-Z in the water oxidation mechanism, we have studied the hydrogen bonding interactions of Y-Z and its photooxidized neutral radical Y-Z(center dot) together with the interaction of the coupled His residue, D1-His190, using light-induced Fourier transform infrared (FTIR) difference spectroscopy. The Y-Z(center dot)-minus-Y-Z FTIR difference spectrum of Mn-depleted PSII core complexes exhibited a broad positive feature around 2800 cm(-1), which was absent in the corresponding spectrum of another redox-active tyrosine Y-D (D2-Tyr160). Analyses by N-15 and H/D substitutions, examination of the pH dependence, and density functional theory and quantum mechanics/molecular mechanics (QM/MM) calculations showed that this band arises from the N-H stretching vibration of the protonated cation of D1-His190 forming a charge-assisted strong hydrogen bond with Y-Z(center dot). This result provides strong evidence that the proton released from Y-Z upon its oxidation is trapped in D1-His190 and a positive charge remains on this His. The broad feature of the similar to 2800 cm(-1) band reflects a large proton polarizability in the hydrogen bond between Y-Z(center dot) and HisH(+). QM/MM calculations further showed that upon Y-Z oxidation the hydrogen bond network is rearranged and one water molecule moves toward D1-His190. From these data, a novel proton transfer mechanism via Y-Z(center dot)-HisH(+) is proposed, in which hopping of the polarizable proton of HisH(+) to this water triggers the transfer of the proton from substrate water to the luminal side. This proton transfer mechanism could be functional in the S-2 -> S-3 transition, which requires proton release before electron transfer because of an excess positive charge on the Mn4Ca cluster.

    DOI: 10.1021/bi500237y

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  • Comparison of oligomeric states and polypeptide compositions of fucoxanthin chlorophyll a/c-binding protein complexes among various diatom species 査読

    Ryo Nagao, Shuji Takahashi, Takehiro Suzuki, Naoshi Dohmae, Katsuyoshi Nakazato, Tatsuya Tomo

    PHOTOSYNTHESIS RESEARCH   117 ( 1-3 )   281 - 288   2013年11月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Fucoxanthin chlorophyll a/c-binding protein (FCP) is a unique light-harvesting apparatus in diatoms. Several biochemical characteristics of FCP oligomer and trimer from different diatom species have been reported previously. However, the integration of information about molecular organizations and polypeptides of FCP through a comparison among diatoms has not been published. In this study, we used two-dimensional clear-native/SDS-PAGE to compare the oligomeric states and polypeptide compositions of FCP complexes from four diatoms: Chaetoceros gracilis, Thalassiosira pseudonana, Cyclotella meneghiniana, and Phaeodactylum tricornutum. FCP oligomer was found in C. gracilis, T. pseudonana, and C. meneghiniana, but not in P. tricornutum. The oligomerization varied among the three diatoms, although a predominant subunit having similar molecular weight was recovered in each FCP oligomer. These results suggest that the predominant subunit is involved in the formation of high FCP oligomerization in each diatom. In contrast, FCP trimer was found in all the diatoms. The trimerizations were quite similar, whereas the polypeptide compositions were markedly different. On the basis of this information and that from mass spectrometric analyses, the gene products in each FCP complex were identified in T. pseudonana and P. tricornutum. Based on these results, we discuss the role of FCP oligomer and trimer from the four diatoms.

    DOI: 10.1007/s11120-013-9903-5

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  • Crystal Structure of Psb31, a Novel Extrinsic Protein of Photosystem II from a Marine Centric Diatom and Implications for Its Binding and Function 査読

    Ryo Nagao, Michihiro Suga, Ayako Niikura, Akinori Okumura, Faisal Hammad Mekky Koua, Takehiro Suzuki, Tatsuya Tomo, Isao Enami, Jian-Ren Shen

    BIOCHEMISTRY   52 ( 38 )   6646 - 6652   2013年9月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Psb31 is a fifth extrinsic protein found in photosystem II (PSII) of a centric diatom, Chaetoceros gracilis. The protein has been shown to bind directly to PSII in the absence of other extrinsic proteins and serves in part as a substitute for PsbO in supporting oxygen evolution. We report here the crystal structure of Psb31 at a resolution of 1.55 angstrom. The structure of Psb31 was composed of two domains, one major, N-terminal four helical domain and one minor, flexible C-terminal domain. The four helices in the N-terminal domain were arranged in an up down-up-down-fold, which appeared unexpectedly to be similar to the structure of spinach PsbQ in spite of their low sequence homology. This suggests that the centric diatom PSII contains another PsbQ- type extrinsic protein in addition to the original PsbQ protein found in the organism. On the other hand, the C-terminal domain of Psb31 has a unique structure composed of one loop and one short helix. Based on these structural analysis and chemical cross-linking experiments, residues responsible for the binding of Psb31 to PSII intrinsic proteins were suggested. The results are discussed in relation to the copy number of extrinsic proteins in higher plant PSII.

    DOI: 10.1021/bi400770d

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  • Structural coupling of extrinsic proteins with the oxygen-evolving center in red algal photosystem II as revealed by light-induced FTIR difference spectroscopy 査読

    Chihiro Uno, Ryo Nagao, Hiroyuki Suzuki, Tatsuya Tomo, Takumi Noguchi

    Biochemistry   52 ( 34 )   5705 - 5707   2013年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Effects of binding of extrinsic proteins (PsbO, PsbQ′, PsbV, and PsbU) on the structure of the oxygen-evolving center (OEC) in photosystem II core complexes from a red alga, Cyanidium caldarium, were studied using Fourier transform infrared (FTIR) spectroscopy. S2-minus-S1 FTIR difference spectra showed that the protein conformations of the OEC, revealed by the changes in amide I and II bands, were significantly altered upon depletion of all the extrinsic proteins, but mostly recovered when PsbV was rebound with the support of other extrinsic proteins. The recovery of protein conformations correlated well with O2 evolution activity. This PsbV function of retaining a proper OEC conformation in red algae resembles that of PsbP in higher plants reported previously. © 2013 American Chemical Society.

    DOI: 10.1021/bi4009787

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  • High excitation energy quenching in fucoxanthin chlorophyll a/c-binding protein complexes from the diatom Chaetoceros gracilis 査読

    Ryo Nagao, Makio Yokono, Seiji Akimoto, Tatsuya Tomo

    Journal of Physical Chemistry B   117 ( 23 )   6888 - 6895   2013年6月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society  

    The fucoxanthin chlorophyll (Chl) a/c-binding protein (FCP) is responsible for excellent light-harvesting strategies that enable survival in fluctuating light conditions. Here, we report the light-harvesting and quenching states of two FCP complexes, FCP-A and FCP-B/C, isolated from the diatom Chaetoceros gracilis. Pigment analysis revealed that FCP-A is enriched in Chl c, whereas FCP-B/C is enriched in diadinoxanthin, reflecting differences in low-temperature steady-state absorption and fluorescence spectra of each FCP complex. Time-resolved fluorescence spectra were measured at 77 K, and the characteristic lifetimes were determined using global fitting analysis of the spectra. Tens of picosecond (ps) components revealed energy transfer to low-energy Chl a from Chls a and c, whereas the other components showed only fluorescence decay components with no concomitant rise components. The normalized amplitudes of hundreds of picosecond components were relatively 30% in the total fluorescence, whereas those of longest-lived components were 60%. The hundreds of picosecond components were assigned as excitation energy quenching, whereas the longest-lived components were assigned as fluorescence from the final energy traps. These results suggest that 30% of FCP complex forming quenching state and the other 60% of FCP complex forming light-harvesting state exist heterogeneously in each FCP fraction under continuous low-light condition. © 2013 American Chemical Society.

    DOI: 10.1021/jp403923q

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  • Light-independent biosynthesis and assembly of the photosystem II complex in the diatom Chaetoceros gracilis 査読

    Ryo Nagao, Tatsuya Tomo, Rei Narikawa, Isao Enami, Masahiko Ikeuchi

    FEBS LETTERS   587 ( 9 )   1340 - 1345   2013年5月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Diatoms can survive for long periods in the dark. However, how biosynthesis of photosynthetic proteins contributes to survival in the dark is poorly understood. Using a radiolabeling technique, we examined whether de novo biosynthesis and assembly of photosynthetic proteins differs in light-adapted vs. dark-adapted marine diatoms (Chaetoceros gracilis). In light-adapted cells, D1 protein was heavily radiolabeled owing to rapid turnover of photosystem II (PSII). In dark-adapted cells (>24 h), the radiolabeling patterns of PSII components changed, but the PSII dimer still formed. Therefore, diatoms may regulate the biosynthesis of photosynthetic proteins for long-term survival in the dark. (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.febslet.2013.02.050

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  • Proteases are associated with a minor fucoxanthin chlorophyll a/c-binding protein from the diatom, Chaetoceros gracilis 査読

    Ryo Nagao, Tatsuya Tomo, Eri Noguchi, Takehiro Suzuki, Akinori Okumura, Rei Narikawa, Isao Enami, Masahiko Ikeuchi

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1817 ( 12 )   2110 - 2117   2012年12月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We previously showed that most subunits in the oxygen-evolving photosystem II (PSII) preparation from the diatom Chaetoceros gracilis are proteolytically unstable. Here, we focused on identifying the proteases that cleave PSII subunits in thylakoid membranes. Major PSII subunits and fucoxanthin chlorophyll (Chl) a/c-binding proteins (FCPs) were specifically degraded in thylakoid membranes. The PSI subunits, PsaA and PsaB, were slowly degraded, and cytochrome f was barely degraded. Using zymography, proteolytic activities for three metalloproteases (116, 83, and 75 kDa) and one serine protease (156 kDa) were detected in thylakoid membranes. Two FCP fractions (FCP-A and FCP-B/C) and a photosystem fraction were separated by sucrose gradient centrifugation using dodecyl maltoside-solubilized thylakoids. The FCP-A fraction featured enriched Chl c compared with the bulk of FCP-B/C. Zymography revealed that 116, 83, and 94 kDa metalloproteases were mostly in the FCP-A fraction along with the 156 kDa serine protease. When solubilized thylakoids were separated with clear-native PAGE, zymography detected only the 83 kDa metalloprotease in the FCP-A band. Because FCP-A is selectively associated with PSII, these FCP-A-associated metalloproteases and serine protease may be responsible for the proteolytic degradation of FCPs and PSII in thylakoid membranes. (C) 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.bbabio.2012.08.005

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  • Luminescence of singlet oxygen in photosystem II complexes isolated from cyanobacterium Synechocystis sp PCC6803 containing monovinyl or divinyl chlorophyll a 査読

    Tatsuya Tomo, Hayato Kusakabe, Ryo Nagao, Hisashi Ito, Ayumi Tanaka, Seiji Akimoto, Mamoru Mimuro, Shigetoshi Okazaki

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1817 ( 8 )   1299 - 1305   2012年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The luminescence spectrum of singlet oxygen produced upon excitation at 674 nm in the photochemically active photosystem II (PS II) complexes isolated from cyanobacterium Synechocystis sp. PCC 6803 containing different types of chlorophyll, i.e., monovinyl (wild-type) or divinyl (genetically modified) chlorophyll a. The yield of singlet oxygen, estimated using methylene blue as the standard, from the divinyl-chlorophyll PS II complex was more than five times greater than that from the monovinyl-chlorophyll PS II complex. These results are consistent with the observed difference in the sensitivity towards high intensity of light between the two cyanobacterial strains. The yield of singlet oxygen appeared to increase with the level of triplet chlorophyll, in the divinyl-chlorophyll PS II complex. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. (C) 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.bbabio.2012.02.018

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  • Alterations in photosynthetic pigments and amino acid composition of D1 protein change energy distribution in photosystem II 査読

    Makio Yokono, Tatsuya Tomo, Ryo Nagao, Hisashi Ito, Ayumi Tanaka, Seiji Akimoto

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1817 ( 5 )   754 - 759   2012年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The marine cyanobacterium Prochlorococcus marinus accumulates divinyl chlorophylls instead of monovinyl chlorophylls to harvest light energy. As well as this difference in its chromophore composition, some amino acid residues in its photosystem II D1 protein were different from the conserved amino acid residues in other photosynthetic organisms. We examined PSII complexes isolated from mutants of Synechocystis sp. PCC 6803, in which chromophore and D1 protein were altered (Hisashi Ito and Ayumi Tanaka, 2011) to clarify the effects of chromophores/D1 protein composition on the excitation energy distribution. We prepared the mutants accumulating divinyl chlorophyll (DV mutant). The amino acid residues of V205 and G282 in the D1 protein were substituted with M205 and C282 in the DV mutant to mimic Prochlorococcus D1 protein (DV-V205M/G282C mutant). Isolated PSII complexes were analyzed by time-resolved fluorescence spectroscopy. Energy transfer in CP47 was interrupted in PSII containing divinyl chlorophylls. The V205M/G282C mutation did not recover the energy transfer pathway in CP47, instead, the mutation allowed the excitation energy transfer from CP43 to CP47, which neighbors in the PSII dimer. Mutual orientation of the subcomplexes of PSII might be affected by the substitution. The changes of the energy transfer pathways would reduce energy transfer from antennae to the PSII reaction center, and allow Prochlorococcus to acquire light tolerance. (C) 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.bbabio.2012.02.009

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  • Binding and Functional Properties of Five Extrinsic Proteins in Oxygen-evolving Photosystem II from a Marine Centric Diatom, Chaetoceros gracilis 査読

    Ryo Nagao, Akira Moriguchi, Tatsuya Tomo, Ayako Niikura, Saori Nakajima, Takehiro Suzuki, Akinori Okumura, Masako Iwai, Jian-Ren Shen, Masahiko Ikeuchi, Isao Enami

    JOURNAL OF BIOLOGICAL CHEMISTRY   285 ( 38 )   29191 - 29199   2010年9月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

    Oxygen-evolving photosystem II (PSII) isolated from a marine centric diatom, Chaetoceros gracilis, contains a novel extrinsic protein (Psb31) in addition to four red algal type extrinsic proteins of PsbO, PsbQ', PsbV, and PsbU. In this study, the five extrinsic proteins were purified from alkaline Tris extracts of the diatom PSII by anion and cation exchange chromatographic columns at different pH values. Reconstitution experiments in various combinations with the purified extrinsic proteins showed that PsbO, PsbQ', and Psb31 rebound directly to PSII in the absence of other extrinsic proteins, indicating that these extrinsic proteins have their own binding sites in PSII intrinsic proteins. On the other hand, PsbV and PsbU scarcely rebound to PSII alone, and their effective bindings required the presence of all of the other extrinsic proteins. Interestingly, PSII reconstituted with Psb31 alone considerably restored the oxygen evolving activity in the absence of PsbO, indicating that Psb31 serves as a substitute in part for PsbO in supporting oxygen evolution. A significant difference found between PSIIs reconstituted with Psb31 and with PsbO is that the oxygen evolving activity of the former is scarcely stimulated by Cl(-) and Ca(2+) ions but that of the latter is largely stimulated by these ions, although rebinding of PsbV and PsbU activated oxygen evolution in the absence of Cl(-) and Ca(2+) ions in both the former and latter PSIIs. Based on these results, we proposed a model for the association of the five extrinsic proteins with intrinsic proteins in diatom PSII and compared it with those in PSIIs from the other organisms.

    DOI: 10.1074/jbc.M110.146092

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  • Topological Analysis of the Extrinsic PsbO, PsbP and PsbQ Proteins in a Green Algal PSII Complex by Cross-Linking with a Water-Soluble Carbodiimide 査読

    Ryo Nagao, Takehiro Suzuki, Akinori Okumura, Ayako Niikura, Masako Iwai, Naoshi Dohmae, Tatsuya Tomo, Jian-Ren Shen, Masahiko Ikeuchi, Isao Enami

    PLANT AND CELL PHYSIOLOGY   51 ( 5 )   718 - 727   2010年5月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    The close association of the extrinsic PsbO, PsbP and PsbQ proteins with PSII core subunits in oxygen-evolving PSII complexes from a green alga, Chlamydomonas reinhardtii, was examined by cross-linking experiments with a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The green algal PSII complexes treated with EDC were washed with alkaline Tris to remove the non-cross-linked extrinsic proteins, and then applied to Blue-Native-PAGE to prepare PSII core complexes. The extrinsic proteins cross-linked with PSII core complexes were detected by immunoblotting analysis using antibodies against extrinsic proteins and PSII core subunits. The results showed that the PsbO, PsbP and PsbQ proteins directly associated with CP47, the subunit of cytochrome b559 and a small subunit in PSII core complexes, respectively, through electrostatic interactions. In addition, a cross-linked product between the PsbP and PsbQ proteins was found in alkaline Tris extracts of EDC-treated PSII complexes, and its cross-linked site was examined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF-MS) after digestions with trypsin and endoproteinase Asp-N. The results demonstrated that the positively charged amino group of K176 on the PsbP protein electrostatically interacts with the negatively charged carboxyl group of D28 on the PsbQ protein. These binding properties of the extrinsic proteins in the green algal PSII were compared with those in higher plant PSII.

    DOI: 10.1093/pcp/pcq042

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  • Species-dependence of the redox potential of the primary quinone electron acceptor Q(A) in photosystem II verified by spectroelectrochemistry 査読

    Tadao Shibamoto, Yuki Kato, Ryo Nagao, Takuya Yamazaki, Tatsuya Tomo, Tadashi Watanabe

    FEBS LETTERS   584 ( 8 )   1526 - 1530   2010年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY  

    The redox potentials E-m(Q(A)/Q(A)) of the primary quinone electron acceptor Q(A) in oxygen-evolving photosystem II complexes of three species were determined by spectroelectrochemistry. The E-m(Q(A)/Q(A)(-)) values were experimentally found to be -162 +/- 3 mV for a higher plant spinach, -171 +/- 3 mV for a green alga Chlamydomonas reinhardtii and -104 +/- 4 mV vs. SHE for a red alga Cyanidioschyzon merolae. On the basis of possible deviations for the experimental values, as estimated to differ by 9-29 mV from each true value, plausible causes for such remarkable species-dependence of E-m(Q(A)/Q(A)(-)) are discussed, mainly by invoking the effects of extrinsic subunits on the delicate structural environment around Q(A). (C) 2010 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.febslet.2010.03.002

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  • Purification and characterization of a stable oxygen-evolving Photosystem II complex from a marine centric diatom, Chaetoceros gracilis 査読

    Ryo Nagao, Tatsuya Tomo, Eri Noguchi, Saori Nakajima, Takehiro Suzuki, Akinori Okumura, Yasuhiro Kashino, Mamoru Mimuro, Masahiko Ikeuchi, Isao Enami

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1797 ( 2 )   160 - 166   2010年2月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Oxygen-evolving Photosystem II particles (crude PSII) retaining a high oxygen-evolving activity have been prepared from a marine centric diatom, Chaetoceros gracilis (Nagao et al., 2007). The crude PSII, however, contained a large amount of fucoxanthin chlorophyll a/c-binding proteins (FCP). In this study, a purified PSII complex which was deprived of major components of FCP was isolated by one step of anion exchange chromatography from the crude PSII treated with Triton X-100. The purified PSII was still associated with the five extrinsic proteins of PsbO, PsbQ', PsbV, Psb31 and PsbU, and showed a high oxygen-evolving activity of 2135 mu mol O(2) (mg Chl a)(-1) h(-1) in the presence of phenyl-p-benzoquinone which was virtually independent of the addition of CaCl(2). This activity is more than 2.5-fold higher than the activity of the crude PSII. The activity was completely inhibited by 3-(3,4)-dichlorophenyl-(1,1)-dimethylurea (DCMU). The purified PSII contained 42 molecules of Chl a, 2 molecules of diadinoxanthin and 2 molecules of Chl c on the basis of two molecules of pheophytin a, and showed typical absorption and fluorescence spectra similar to those of purified PSIIs from the other organisms. In this study, we also found that the crude PSII was significantly labile, as a significant inactivation of oxygen evolution, chlorophyll bleaching and degradation of PSII subunits were observed during incubation at 25 degrees C in the dark. In contrast, these inactivation, bleaching and degradation were scarcely detected in the purified PSII. Thus, we succeeded for the first time in preparation of a stable PSII from diatom cells. (C) 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.bbabio.2009.09.008

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  • Redox potential of pheophytin a in photosystem II of two cyanobacteria having the different special pair chlorophylls 査読

    Suleyman I. Allakhverdiev, Tatsuya Tomo, Yuichiro Shimada, Hayato Kindo, Ryo Nagao, Vyacheslav V. Klimov, Mamoru Mimuro

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   107 ( 8 )   3924 - 3929   2010年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATL ACAD SCIENCES  

    Water oxidation by photosystem (PS) II in oxygenic photosynthetic organisms is a major source of energy on the earth, leading to the production of a stable reductant. Mechanisms generating a high oxidation potential for water oxidation have been a major focus of photosynthesis research. This potential has not been estimated directly but has been measured by the redox potential of the primary electron acceptor, pheophytin (Phe)a. However, the reported values for Phe a are still controversial. Here, we measured the redox potential of Phe a under physiological conditions (pH 7.0; 25 degrees C) in two cyanobacteria with different special pair chlorophylls (Chls): Synechocystis sp. PCC 6803, whose special pair for PS II consists of Chl a, and Acaryochloris marina MBIC 11017, whose special pair for PS II consists of Chl d. We obtained redox potentials of -536 +/- 8 mV for Synechocystis sp. PCC 6803 and -478 +/- 24 mV for A. marina on PS II complexes in the presence of 1.0 M betaine. The difference in the redox potential of Phe a between the two species closely corresponded with the difference in the light energy absorbed by Chl a versus Chl d. We estimated the potentials of the special pair of PS II to be 1.20 V and 1.18 V for Synechocystis sp. PCC 6803 (P680) and A. marina (P713), respectively. This clearly indicates conservation in the properties of water-oxidation systems in oxygenic photosynthetic organisms, irrespective of the special-pair chlorophylls.

    DOI: 10.1073/pnas.0913460107

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  • A novel protein in Photosystem II of a diatom Chaetoceros gracilis is one of the extrinsic proteins located on lumenal side and directly associates with PSII core components 査読

    Akinori Okumura, Ryo Nagao, Takehiro Suzuki, Satoshi Yamagoe, Masako Iwai, Katsuyoshi Nakazato, Isao Enami

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1777 ( 12 )   1545 - 1551   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The gene encoding a novel extrinsic protein (Psb31) found in Photosystem II (PSII) of a diatom, Chaetoceros gracilis, was cloned and sequenced. The deduced protein contained three characteristic leader sequences targeted for chloroplast endoplasmic reticulum membrane, chloroplast envelope membrane and thylakoid membrane, indicating that Psb31 is encoded in the nuclear genome and constitutes one of the extrinsic proteins located on the lumenal side. Homologous genes were found in a red alga and chromophytic algae but not in other organisms. Genes encoding the other four extrinsic proteins in C gracilis PSII were also cloned and sequenced, and their leader sequences were characterized and compared. To search for the nearest neighbor relationship between Psb31 and the other PSII components, we crosslinked the PSII particles with the water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and found that Psb31 directly associates with PSII core components through electrostatic interaction, suggesting that the novel Psb31 protein is one of the extrinsic proteins constituting the functional oxygen-evolving complex of C. gracilis PSII. (C) 2008 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.bbabio.2008.09.004

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  • Isolation and characterization of oxygen-evolving thylakoid membranes and Photosystem II particles from a marine diatom Chaetoceros gracilis 査読

    Ryo Nagao, Akiko Ishii, Osamu Tada, Takehiro Suzuki, Naoshi Dohmae, Akinori Okumura, Masako Iwai, Takeshi Takahashi, Yasuhiro Kashino, Isao Enami

    BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS   1767 ( 12 )   1353 - 1362   2007年12月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Thylakoid membranes retaining high oxygen-evolving activity (about 250 mu mol O-2/mg Chl/h) were prepared from a marine centric diatom, Chaetoceros gracilis, after disruption of the cells by freeze-thawing. We also succeeded in purification of Photosystem 11 (PSII) particles by differential centrifugation of the thylakoid membranes after treatment with 1% Triton X-100. The diatom PSII particles showed an oxygen-evolving activity of 850 and 1045 mu mol O-2/mg Chl/h in the absence and presence of CaCl2, respectively. The PSII particles contained fucoxanthin chlorophyll a/c-binding proteins in addition to main intrinsic proteins of CP47, CP43, D2, D1, cytochrome b559, and the antenna size was estimated to be 229 Chl a per 2 molecules of pheophytin. Five extrinsic proteins were stoichiometrically released from the diatom PSII particles by alkaline Tris-treatment. Among these five extrinsic proteins, four proteins were red algal-type extrinsic proteins, namely, PsbO, PsbQ', PsbV and PsbU, whereas the other one was a novel, hypothetical protein. This is the first report on isolation and characterization of diatom PSII particles that are highly active in oxygen evolution and retain the full set of extrinsic proteins including an unknown protein. (C) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.bbabio.2007.10.007

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  • Aromatic structure of Tyrosine-92 in the extrinsic PsbU protein of red algal Photosystem II is important for its functioning 査読

    Akinori Okumura, Masanori Sano, Takehiro Suzuki, Hiroyasu Tanaka, Ryo Nagao, Katsuyoshi Nakazato, Masako Iwai, Hideyuki Adachi, Jian-Ren Shen, Isao Enami

    FEBS LETTERS   581 ( 27 )   5255 - 5258   2007年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    PsbU is one of the extrinsic proteins in red algal Photosystem II (PSII) and functions to optimize the availability of Ca2+ and Cl- cofactors for water oxidation. To determine the functional residue of PsbU, we constructed various PsbU mutants from a red alga Cyanidium caldarium and reconstituted these mutants with the red algal PSII. The results revealed that Tyr-92 of PsbU, especially its aromatic ring, was essential for maintaining its function. From the crystal structure of PSII, Tyr-92 is located close to Pro-340 of D1, suggesting that the aromatic ring of Tyr-92 interacts with the CH group of Pro-340 of D1, and this CH/pi interaction is important for the optimal function of the Mn4Ca-cluster. (C) 2007 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.

    DOI: 10.1016/j.febslet.2007.10.015

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MISC

  • 進化すると色素タンパク質が増える?珪藻の光化学系I-集光性色素タンパク質複合体の立体構造解明

    長尾 遼

    プレスリリース   2020年5月

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    掲載種別:記事・総説・解説・論説等(その他)  

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  • 褐色の要因となる巨大な光合成膜タンパク質複合体の立体構造の解明

    長尾 遼

    Chem-Station   2019年9月

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  • 褐色を呈する光化学系II-集光性色素タンパク質複合体の立体構造を解明~光合成生物の進化と多様化を解明する糸口に~

    長尾 遼

    プレスリリース   2019年7月

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  • 緑色でないとダメですか?

    長尾 遼

    CanAppleニュース 第80号   2019年5月

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  • 表紙・裏表紙・表紙の紹介 招待

    長尾遼

    光合成研究   31 ( 1 )   2021年5月

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    担当区分:筆頭著者, 責任著者   記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

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  • 珪藻の強光に対する防御策:集光性色素タンパク質の分子調節機構の解明

    長尾 遼

    プレスリリース   2020年12月

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  • 鉄欠乏環境で耐え忍ぶための光合成反応:isiA遺伝子の多様な発現機構と機能の解明

    長尾 遼

    プレスリリース   2020年10月

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    掲載種別:記事・総説・解説・論説等(その他)  

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  • ピングイオ藻の集光性色素タンパク質の特性解明:アルカリpHで誘導される太陽光エネルギー利用機構を明らかに

    長尾 遼

    プレスリリース   2020年9月

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  • To quench or not to quench: Understanding the role of a cyanobacterial photosystem protein

    EurekAlert!   2020年7月

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  • New study resolves mystery surrounding unique light-harvesting structures in algae

    EurekAlert!   2020年7月

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  • 目に見える光がなくても大丈夫!?遠赤色光で光合成を行えるシアノバクテリアの秘密を解明 ~光化学系Iにおける、クロロフィルfの位置と機能の特定~

    鞆 達也

    プレスリリース   2020年1月

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    掲載種別:記事・総説・解説・論説等(その他)  

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  • 四量体を形成する光化学系Ⅰの立体構造を解明~光合成生物の適応進化を解明する手がかりに~

    加藤 公児

    プレスリリース   2019年10月

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    掲載種別:記事・総説・解説・論説等(その他)  

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  • クライオ電子顕微鏡単粒子解析による光合成超複合体の構造解析 査読

    宮崎直幸, 長尾遼, 加藤公児, 沈建仁, 秋田総理

    光合成研究   28   112 - 118   2018年

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    掲載種別:記事・総説・解説・論説等(学術雑誌)  

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  • 藻類の多様性を利用した光化学系研究 査読

    鞆達也, 山田聖人, 清水信介, 伊藤道俊, 長尾遼

    光合成研究   25   105 - 112   2015年

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    掲載種別:記事・総説・解説・論説等(学術雑誌)  

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  • Metal and serine proteases in the crude photosystem II particles from a diatom, Chaetoceros gracilis

    Nagao, R, Noguchi, E, Tomo, T, Enami, I, Ikeuchi, M

    In Photosynthesis Research for Food, Fuel and the Future (eds. T. Kuang, C. Lu, and L. Zhang) 15th International Conference on Photosynthesis   83 - 85   2013年

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    掲載種別:記事・総説・解説・論説等(国際会議プロシーディングズ)  

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  • Acaryochloris marinaの光化学系IIの単離精製と性質 査読

    小島茜, 金藤隼人, 長尾遼, 三室守, 鞆達也

    光合成研究   21   55 - 58   2011年

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  • 珪藻Chaetoceros gracilisの酸素発生光化学系II複合体の単離と解析 査読

    長尾遼, 鞆達也, 池内昌彦, 榎並勲

    光合成研究   19   109 - 113   2009年

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    掲載種別:記事・総説・解説・論説等(学術雑誌)  

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  • Structures and functions of the extrinsic proteins of photosystem II from different species 査読

    Isao Enami, Akinori Okumura, Ryo Nagao, Takehiro Suzuki, Masako Iwai, Jian-Ren Shen

    PHOTOSYNTHESIS RESEARCH   98 ( 1-3 )   349 - 363   2008年10月

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    記述言語:英語   掲載種別:記事・総説・解説・論説等(学術雑誌)   出版者・発行元:SPRINGER  

    This minireview presents a summary of information available on the variety and binding properties of extrinsic proteins that form the oxygen-evolving complex of photosystem II (PSII) of cyanobacteria, red alga, diatom, green alga, euglena, and higher plants. In addition, the structure and function of extrinsic PsbO, PsbV, and PsbU proteins are summarized based on the crystal structure of thermophilic cyanobacterial PSII together with biochemical and genetic studies from various organisms.

    DOI: 10.1007/s11120-008-9343-9

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  • Cloning and sequence analyses of five extrinsic proteins in diatom PSII

    Okumura, A, Nakazato, K, Yamagoe, S, Nagao, R, Suzuki, T, Iwai, M, Enami, I

    In Photosynthesis. Energy from the Sun. (eds. J. Allen, E. Gantt, J. Golbeck, and B. Osmond) 14th International Conference on Photosynthesis   475 - 478   2008年

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    掲載種別:記事・総説・解説・論説等(国際会議プロシーディングズ)  

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  • Isolation of PSII retaining high oxygen-evolving activity from a marine diatom, Chaetoceros gracilis

    Nagao, R, Suzuki, T, Dohmae, N, Okumura, A, Iwai, M, Takahashi, T, Kashino, Y, Enami, I

    In Photosynthesis. Energy from the Sun. (eds. J. Allen, E. Gantt, J. Golbeck, and B. Osmond) 14th International Conference on Photosynthesis   471 - 474   2008年

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講演・口頭発表等

  • 機能構造研究に基づく光合成色素蛋白質の分子進化 招待

    長尾 遼

    第62回日本植物生理学会  2021年3月14日 

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    開催年月日: 2021年3月14日 - 2021年3月16日

    記述言語:日本語   会議種別:シンポジウム・ワークショップ パネル(指名)  

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  • 天然光合成における見た目の色の違いの分子基盤 招待

    長尾 遼

    人工光合成研究センター 第1回若手研究者研究発表会  2021年8月17日 

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    記述言語:日本語   会議種別:口頭発表(招待・特別)  

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  • 光合成を支える葉緑体色素タンパク質複合体の機能・構造・進化 招待

    長尾 遼

    第23回植物オルガネラワークショップ  2021年3月13日 

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    記述言語:日本語   会議種別:シンポジウム・ワークショップ パネル(指名)  

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  • 光化学系膜タンパク質複合体のクライオ電顕構造解析 招待

    長尾 遼

    第27回「光合成セミナー2019:反応中心と色素系の多様性」  2019年7月13日 

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    記述言語:日本語   会議種別:口頭発表(招待・特別)  

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  • Hydrogen-bond network around Yz controls proton transfer in photosynthetic water oxidation 招待

    Nagao, R, Ueoka-Nakanishi, H, Noguchi, T

    7th OCARINA International Symposium  2016年3月17日 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • Role of the hydrogen bond network around Yz in photosynthetic water oxidation 招待

    Nagao, R, Ueoka-Nakanishi, H, Noguchi, T

    International Meeting Photosynthesis Research for Sustainability-2015  2015年9月21日 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

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受賞

  • Young Talents Award

    2015年9月   International Meeting Photosynthesis Research for Sustainability  

    長尾 遼

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  • 三室賞

    2015年7月   光合成セミナー:反応中心と色素系の多様性  

    長尾 遼

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  • 最優秀ポスター賞

    2009年5月   日本光合成研究会  

    長尾 遼

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共同研究・競争的資金等の研究

  • 全可視光を吸収する光合成色素蛋白質の創出

    研究課題/領域番号:21K19085  2021年07月 - 2023年03月

    日本学術振興会  科学研究費助成事業 挑戦的研究(萌芽)  挑戦的研究(萌芽)

    長尾 遼

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    配分額:6500000円 ( 直接経費:5000000円 、 間接経費:1500000円 )

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  • 好熱性シアノバクテリア由来光合成超複合体の機能・構造解明

    研究課題/領域番号:20K06528  2020年04月 - 2023年03月

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    川上 恵典, 長尾 遼

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    配分額:4420000円 ( 直接経費:3400000円 、 間接経費:1020000円 )

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  • フィコビリソーム-四量体光化学系I超複合体の構造生物学的研究

    研究課題/領域番号:20H02914  2020年04月 - 2023年03月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    加藤 公児, 長尾 遼

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    配分額:17940000円 ( 直接経費:13800000円 、 間接経費:4140000円 )

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  • 赤色進化系統におけるプロトン駆動力により制御される光捕集適応機構の解明

    研究課題/領域番号:19H04726  2019年04月 - 2021年03月

    日本学術振興会  科学研究費助成事業 新学術領域研究(研究領域提案型)  新学術領域研究(研究領域提案型)

    長尾 遼

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    担当区分:研究代表者  資金種別:競争的資金

    配分額:4030000円 ( 直接経費:3100000円 、 間接経費:930000円 )

    集光性色素タンパク質(LHC)は、光エネルギーを捕集し、光化学系タンパク質(PSI、PSII)へと伝達する重要な役割を担う。LHCは光合成生物種間で多様であり、タンパク質構造の違いに加え、色素分子の種類や数の違いも見出されている。このようなLHCの広い多様性は、光合成生物の見た目の色の違いをもたらす。色の違いにより、励起エネルギー伝達機構も異なることが知られている。励起エネルギー伝達は様々な摂動により変化し、中でもpHによる変化は、色素分子周辺の構造変化が要因となり、色素間相互作用の変化よって生じると考えられている。光合成生物は光が強いと感じると、光阻害が起こる。光阻害が進行することによりチラコイド膜のルーメン側が酸性化される。このように生体内でもpH変化は容易に起こるため、pH変化による励起エネルギー伝達機構の理解は光防御機構を知る上でも重要な位置づけにある。本研究は褐色を呈する珪藻を材料とし、珪藻の特殊なLHCであるフコキサンチンクロロフィルタンパク質(FCP)のpH変化による励起エネルギー伝達機構の解明を目指す。
    珪藻のPSI-FCPI超複合体を用いて、pH5.0, 6.5, 8.0のそれぞれに順応させ、時間分解蛍光分光測定を行った。pH5.0において蛍光の減衰が促進された。さらに、pH変化により励起エネルギー移動経路の変化も観測された。酸性pHによって誘導されるエネルギー移動経路およびエネルギー消光の変化は、色素分子周辺のタンパク質構造変化に起因するのだろう。これらの結果を論文として纏めた。

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  • 光合成膜タンパク質の結晶化に向けた高純度精製方法の確立

    2018年09月 - 2020年03月

    大阪市立大学  大阪市立大学人工光合成センター共同利用・共同研究助成 

    長尾 遼

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    担当区分:研究代表者  資金種別:競争的資金

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  • 網羅的な部位特異的置換による光合成水分解反応機構の解明

    研究課題/領域番号:17K07442  2017年04月 - 2020年03月

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    長尾 遼

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    担当区分:研究代表者  資金種別:競争的資金

    配分額:4940000円 ( 直接経費:3800000円 、 間接経費:1140000円 )

    植物、藻類、シアノバクテリアのチラコイド膜内に存在する光化学系II膜タンパク質(PSII)は、水を分解し酸素を発生する光反応酵素タンパク質である。本研究は、光合成水分解反応の各素反応に関与するアミノ酸の部位特異的変異体を作成し、変異体から精製したPSIIを用いて赤外分光測定による詳細な反応機構の解明を目指す。
    PSIIの重要なサブユニットであるD1およびD2上のアミノ酸を変異対象とした。D1-Val157, D1-Ser169, D1-Asp170, D1-Asn298, D2-Val156が水分解反応および電子伝達反応において重要な役割を担うことが明らかとなった。

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  • 赤外分光法による光合成水分解反応機構の解明

    研究課題/領域番号:26840091  2014年04月 - 2016年03月

    日本学術振興会  科学研究費助成事業 若手研究(B)  若手研究(B)

    長尾 遼

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    担当区分:研究代表者  資金種別:競争的資金

    配分額:4160000円 ( 直接経費:3200000円 、 間接経費:960000円 )

    酸素発生光合成生物に普遍的な水分解反応の触媒部位であるマンガンクラスターは5つの反応中間状態を持つ。各反応において電子、プロトン、酸素分子が放出される。本研究は、水分解反応によるプロトン放出機構の解明を目的とし、Yzを経由する水素結合ネットワーク上のD1-Asn298に変異導入し、精製した光化学系IIを用いて赤外分光解析した。その結果、このネットワークがS2→S3およびS3→S0遷移においてプロトン移動経路として機能していることが明らかとなった。

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  • 珪藻の酸素発生光化学系II複合体の精製とその特性解析

    2009年04月 - 2012年03月

    日本学術振興会  特別研究員奨励費 

    長尾 遼

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    担当区分:研究代表者  資金種別:競争的資金

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  • 珪藻の酸素発生光化学系II複合体の精製とその特性解析

    研究課題/領域番号:09J03668  2009年 - 2011年

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    長尾 遼

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    配分額:2100000円 ( 直接経費:2100000円 )

    珪藻は、世界中の熱帯雨林が吸収する二酸化炭素量と同程度の量を吸収する水域圏で最も重要な植物プランクトンである。私はこれまでに、海産の中心目珪藻Chaetoceros gracilisから酸素発生光化学系II複合体(系II)を単離し、珪藻の系IIの特性について明らかにしてきた。一方、系IIタンパク質のほとんどが、室温・暗所という条件で分解することを見いだした。本年度は、(1)結晶化に向けた系II標品の更なる精製、(2)高分解活性をもつプロテアーゼの検出、の2点に着目し研究を進めた。
    (1)精製された系IIには、ルビスコや若干のアンテナタンパク質FCPが残っているため、イオン交換クロマトグラフィーによる更なる精製を試みた。しかし、精製の過程で表在性タンパク質が容易に外れてしまうため、界面活性剤の濃度や塩濃度などの更なる条件見当が必要である。
    (2)チラコイド膜を材料とし、プロテアーゼの検出と局在解析を試みた。チラコイド膜タンパク質の分解が、EDTAやPMSFで抑制されたことから、金属型とセリン型のプロテアーゼが作用していると考えられる。カゼインタンパク質を含んだゲルで電気泳動を行いプロテアーゼ活性を検出するzymography法により、3種の金属型プロテアーゼと1種のセリン型プロテアーゼがチラコイド膜から検出された。チラコイド膜を可溶化後、ショ糖密度勾配遠心やNative PAGEにより、プロテアーゼがFCPに結合していることが示唆された。現在、プロテアーゼの同定を進めている。

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