Updated on 2025/04/14

写真a

 
SAKAMOTO Wataru
 
Organization
Scheduled update Professor
Position
Professor
Profile

植物が地球上の様々な環境に適応して生息するしくみ、特に光環境と光合成の適応について研究しています(植物生理学・葉緑体生物学)。酸素発生型の光合成細菌(シアノバクテリア)が細胞内に共生して成立した葉緑体を対象に、光や外的環境により制御される葉緑体の分化や光合成装置の形成と膜の発達、維持機構についてモデル生物を用いて明らかにしています。

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Research Interests

  • 遺伝学

  • 植物生理学

  • Photosynthesis and Photoinhibition

  • Chloroplast Biology

  • オルガネラ遺伝

  • チラコイド膜リモデリング

  • 葉緑体タンパク質分解

Research Areas

  • Life Science / Plant molecular biology and physiology

  • Environmental Science/Agriculture Science / Science in plant genetics and breeding

  • Life Science / Genetics

Education

  • The University of Tokyo   農学系研究科  

    - 1990.3

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  • The University of Tokyo   農学部  

    - 1985.3

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Research History

  • Okayama University   Institute of Plant Science and Resources   Professor

    2010.4

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  • Okayama University   資源生物科学研究所   Professor

    2003.4 - 2010.3

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  • Okayama University   Institute of Plant Science and Resources   Associate Professor (as old post name)

    2000.6 - 2003.3

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  • Institut de Biologie Moléculaire des Plantes, CNRS

    1996.3 - 1996.11

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    Country:France

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  • Okayama University   資源生物科学研究所   Research Assistant

    1993.7 - 2000.5

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Professional Memberships

Committee Memberships

  • Plant and Cell Physiology   Editor-in-Chief  

    2020.3   

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    Committee type:Academic society

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  • 国立科学博物館   特別展「植物 地球を支える仲間たち」監修協力者  

    2019.3 - 2022.4   

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    Committee type:Other

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  • 日本学術会議   連携委員  

    2018.10 - 2023.9   

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    Committee type:Government

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  • 日本植物生理学会   幹事長(理事)  

    2014.1 - 2016.3   

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    Committee type:Academic society

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  • 日本学術振興会学術システム研究センター   生物学専門研究員  

    2012.4 - 2015.3   

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    Committee type:Government

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Papers

  • The thylakoid membrane remodeling protein VIPP1 forms bundled oligomers in tobacco chloroplasts. International journal

    Sarah W Gachie, Alexandre Muhire, Di Li, Akihiro Kawamoto, Noriko Takeda-Kamiya, Yumi Goto, Mayuko Sato, Kiminori Toyooka, Ryo Yoshimura, Tsuneaki Takami, Lingang Zhang, Genji Kurisu, Toru Terachi, Wataru Sakamoto

    Plant physiology   2025.4

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    Language:English   Publishing type:Research paper (scientific journal)  

    The thylakoid membrane (TM) serves as the scaffold for oxygen-evolving photosynthesis, hosting the protein complexes responsible for the light reactions and ATP synthesis. Vesicle Inducing Protein in Plastid 1 (VIPP1), a key protein in TM remodeling, has been recognized as essential for TM homeostasis. In vitro studies of cyanobacterial VIPP1 demonstrated its ability to form large homo-oligomers (> 2 MDa) manifesting as ring-like or filament-like assemblies associated with membranes. Similarly, VIPP1 in Chlamydomonas reinhardtii assembles into rods that encapsulate liposomes or into stacked spiral structures. However, the nature of VIPP1 assemblies in chloroplasts, particularly in Arabidopsis, remains uncharacterized. Here, we expressed Arabidopsis thaliana VIPP1 fused to GFP (AtVIPP1-GFP) in tobacco (Nicotiana tabacum) chloroplasts and performed transmission electron microscopy (TEM). A purified AtVIPP1-GFP fraction was enriched with long filamentous tubule-like structures. Detailed TEM observations of chloroplasts in fixed resin-embedded tissues identified VIPP1 assemblies in situ that appeared to colocalize with GFP fluorescence. Electron tomography demonstrated that the AtVIPP1 oligomers consisted of bundled filaments near membranes, some of which appeared connected to the TM or inner chloroplast envelope at their contact sites. The observed bundles were never detected in wild-type Arabidopsis but were observed in Arabidopsis vipp1 mutants expressing AtVIPP1-GFP. Taken together, we propose that the bundled filaments are the dominant AtVIPP1 oligomers that represent its static state in vivo.

    DOI: 10.1093/plphys/kiaf137

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  • The plastidial protein acetyltransferase GNAT1 forms a complex with GNAT2, yet their interaction is dispensable for state transitions

    Annika Brünje, Magdalena Füßl, Jürgen Eirich, Jean-Baptiste Boyer, Paulina Heinkow, Ulla Neumann, Minna Konert, Aiste Ivanauskaite, Julian Seidel, Shin-Ichiro Ozawa, Wataru Sakamoto, Thierry Meinnel, Dirk Schwarzer, Paula Mulo, Carmela Giglione, Iris Finkemeier

    Molecular & Cellular Proteomics   100850 - 100850   2024.9

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    Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.mcpro.2024.100850

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  • Characterization of organelle DNA degradation mediated by DPD1 exonuclease in the rice genome-edited line

    Md. Faridul Islam, Hiroshi Yamatani, Tsuneaki Takami, Makoto Kusaba, Wataru Sakamoto

    Plant Molecular Biology   114 ( 3 )   2024.6

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    Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    Abstract

    Mitochondria and plastids, originated as ancestral endosymbiotic bacteria, contain their own DNA sequences. These organelle DNAs (orgDNAs) are, despite the limited genetic information they contain, an indispensable part of the genetic systems but exist as multiple copies, making up a substantial amount of total cellular DNA. Given this abundance, orgDNA is known to undergo tissue-specific degradation in plants. Previous studies have shown that the exonuclease DPD1, conserved among seed plants, degrades orgDNAs during pollen maturation and leaf senescence in Arabidopsis. However, tissue-specific orgDNA degradation was shown to differ among species. To extend our knowledge, we characterized DPD1 in rice in this study. We created a genome-edited (GE) mutant in which OsDPD1 and OsDPD1-like were inactivated. Characterization of this GE plant demonstrated that DPD1 was involved in pollen orgDNA degradation, whereas it had no significant effect on orgDNA degradation during leaf senescence. Comparison of transcriptomes from wild-type and GE plants with different phosphate supply levels indicated that orgDNA had little impact on the phosphate starvation response, but instead had a global impact in plant growth. In fact, the GE plant showed lower fitness with reduced grain filling rate and grain weight in natural light conditions. Taken together, the presented data reinforce the important physiological roles of orgDNA degradation mediated by DPD1.

    DOI: 10.1007/s11103-024-01452-x

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    Other Link: https://link.springer.com/article/10.1007/s11103-024-01452-x/fulltext.html

  • Dysfunction of Chloroplast Protease Activity Mitigates pgr5 Phenotype in the Green Algae Chlamydomonas reinhardtii. International journal

    Shin-Ichiro Ozawa, Guoxian Zhang, Wataru Sakamoto

    Plants (Basel, Switzerland)   13 ( 5 )   2024.2

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    Language:English   Publishing type:Research paper (scientific journal)  

    Researchers have described protection mechanisms against the photoinhibition of photosystems under strong-light stress. Cyclic Electron Flow (CEF) mitigates electron acceptor-side limitation, and thus contributes to Photosystem I (PSI) protection. Chloroplast protease removes damaged protein to assist with protein turn over, which contributes to the quality control of Photosystem II (PSII). The PGR5 protein is involved in PGR5-dependent CEF. The FTSH protein is a chloroplast protease which effectively degrades the damaged PSII reaction center subunit, D1 protein. To investigate how the PSI photoinhibition phenotype in pgr5 would be affected by adding the ftsh mutation, we generated double-mutant pgr5ftsh via crossing, and its phenotype was characterized in the green algae Chlamydomonas reinhardtii. The cells underwent high-light incubation as well as low-light incubation after high-light incubation. The time course of Fv/Fm values in pgr5ftsh showed the same phenotype with ftsh1-1. The amplitude of light-induced P700 photo-oxidation absorbance change was measured. The amplitude was maintained at a low value in the control and pgr5ftsh during high-light incubation, but was continuously decreased in pgr5. During the low-light incubation after high-light incubation, amplitude was more rapidly recovered in pgr5ftsh than pgr5. We concluded that the PSI photoinhibition by the pgr5 mutation is mitigated by an additional ftsh1-1 mutation, in which plastoquinone pool would be less reduced due to damaged PSII accumulation.

    DOI: 10.3390/plants13050606

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  • Characterization of tryptophan oxidation affecting D1 degradation by FtsH in the photosystem II quality control of chloroplasts. International journal

    Yusuke Kato, Hiroshi Kuroda, Shin-Ichiro Ozawa, Keisuke Saito, Vivek Dogra, Martin Scholz, Guoxian Zhang, Catherine de Vitry, Hiroshi Ishikita, Chanhong Kim, Michael Hippler, Yuichiro Takahashi, Wataru Sakamoto

    eLife   12   2023.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:eLife Sciences Publications, Ltd  

    Light reaction of photosynthesis is one of the most important reactions for sustaining our environment. Photosystem II (PSII) is the initial site of photosynthetic electron transfer by water oxidation. Light in excess, however, causes the simultaneous production of singlet oxygen, a potent reactive oxygen species (ROS), leading to photo-oxidative damage in PSII. To maintain photosynthetic activity, the PSII reaction center protein D1, which is the primary target of unavoidable photo-oxidative damage, is efficiently degraded by FtsH protease. In PSII subunits, photo-oxidative modifications of several amino acids such as Trp have been indeed documented, whereas the linkage between such modifications and D1 degradation remains elusive. Here, we show that an oxidative post-translational modification of Trp residue at the N-terminal tail of D1 is correlated with D1 degradation by FtsH during high-light stress. We revealed that Arabidopsis mutant lacking FtsH2 had increased levels of oxidative Trp residues in D1, among which an N-terminal Trp-14 was distinctively localized in the stromal side. Further characterization of Trp-14 using chloroplast transformation in Chlamydomonas indicated that substitution of D1 Trp-14 to Phe, mimicking Trp oxidation enhanced FtsH-mediated D1 degradation under high light, although the substitution did not affect protein stability and PSII activity. Molecular dynamics simulation of PSII implies that both Trp-14 oxidation and Phe substitution cause fluctuation of D1 N-terminal tail. Furthermore, Trp-14 to Phe modification appeared to have an additive effect in the interaction between FtsH and PSII core in vivo. Together, our results suggest that the Trp oxidation at its N-terminus of D1 may be one of the key oxidations in the PSII repair, leading to processive degradation by FtsH.

    In photosynthetic organisms, maintenance of photosynthetic light reaction is manifested by so called Photosystem II (PSII) repair system, where the reaction center protein D1 is targeted to photo-oxidative damage and rapidly degraded by the processive protease FtsH. While this system is well known to cope with photoinhibition, the actual oxidation within the D1 polypeptide and its association to degradation remained elusive. Here, we characterized oxidative modification of tryptophan (Trp) residues in the PSII core, and hypothesize that the oxidation of N-terminal Trp is one of the key oxidations in the PSII repair, likely enhancing D1’s accessibility to FtsH.

    DOI: 10.7554/eLife.88822

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Books

  • 光合成

    ( Role: Joint author)

    朝倉書店  2022 

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  • Special Exhibition PLANTS Mainstays of The Planet

    ( Role: Joint author)

    2021.7 

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  • スーパーバイオマス:植物に学ぶ

    坂本 亘, 福田裕穂, 稲田のりこ編( Role: Joint author ,  光合成の効率向上とスーパーバイオマス)

    慶應大学出版会  2016.2 

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  • 光合成研究と産業応用最前線

    加藤裕介, 坂本 亘(光合成の光阻害:光化学系IIの損傷と修復の分子メカニズム)

    エヌティーエス  2014.2 

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  • 光合成辞典

    日本光合成学会  2014 

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Presentations

  • Thylakostasis and membrane remodeling molecules Invited

    Wataru Sakamoto

    US-Japan Binational Photosynthesis Workshop, Tempe, Arizona 

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    Event date: 2023.11.6 - 2023.11.8

    Presentation type:Oral presentation (invited, special)  

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  • The functional significance of membrane remodeling at grana edges in photosynthetic responses to different light intensities in Arabidopsis

    Ogawa, Y, Iwano, M, Kawamoto, A, Kurisu, G, Shikanai, T, Sakamoto, W

    Taiwan-Japan Plant Biology 2023, Taipei, Taiwan 

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    Event date: 2023.10.13 - 2023.10.15

    Presentation type:Poster presentation  

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  • Site-directed mutagenesis and in vivo observation of VIPP1, an ESCRT-III super family protein involved in thylakoid membrane remodeling in Arabidopsis chloroplasts

    Gachie, S.W, Sakamoto, W

    Taiwan-Japan Plant Biology 2023, Taipei, Taiwan 

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    Event date: 2023.10.13 - 2023.10.15

    Presentation type:Poster presentation  

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  • Thylakoid membrane remodeling molecule VIPP1 interacts with HSP70 through its C-terminal tail in Arabidopsis

    Li, D, Ozawa, S.I, Sakamoto, W

    Taiwan-Japan Plant Biology 2023, Taipei, Taiwan 

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    Event date: 2023.10.13 - 2023.10.15

    Presentation type:Poster presentation  

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  • x- and y-type thioredoxins protect photosystem I from photoinhibition under fluctuating light

    Okegawa, Y, Motohashi, K, Sakamoto, W

    Taiwan-Japan Plant Biology 2023, Taipei, Taiwan 

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    Event date: 2023.10.13 - 2023.10.15

    Presentation type:Poster presentation  

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Awards

  • ASPB Enid MacRobbie Corresponding Membership Award

    2023   American Society of Plant Biologists  

    Wataru Sakamoto

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  • 第7回日本光合成シンポジウムベストポスター賞

    2007  

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    Country:Japan

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  • 日本遺伝学会奨励賞

    2001  

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    Country:Japan

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Research Projects

  • チラコスタシスの解明に基づく葉緑体生物学の再構成

    Grant number:24K02044  2024.04 - 2027.03

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    坂本 亘

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    Grant amount:\18590000 ( Direct expense: \14300000 、 Indirect expense:\4290000 )

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  • Elucidating photosynthetic adaptation through the structure of thylakoid membrane remodeling

    Grant number:23H04959  2023.04 - 2028.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Transformative Research Areas (A)

    坂本 亘, 小澤 真一郎

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    Grant amount:\111540000 ( Direct expense: \85800000 、 Indirect expense:\25740000 )

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  • Photosynthesis ubiquity: Supramolecular complexes and their regulations to enable ph otosynthesis all around the globe

    Grant number:23H04957  2023.04 - 2028.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Transformative Research Areas (A)

    栗栖 源嗣, 斉藤 圭亮, 山本 大輔, 白井 剛, 坂本 亘, 日原 由香子, 広瀬 侑, 丸山 真一朗, 田中 亮一, 皆川 純, 吉田 啓亮, 桶川 友季

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    Grant amount:\111280000 ( Direct expense: \85600000 、 Indirect expense:\25680000 )

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  • Thylakoid Membrane Remodeling and Optimization of Photosynthetic Activity

    Grant number:21H02508  2021.04 - 2024.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    坂本 亘

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    Grant amount:\17420000 ( Direct expense: \13400000 、 Indirect expense:\4020000 )

    今年度は、シアノバクテリアで構造が決定されたVIPP1のin vivoでの機能をシロイヌナズナVIPP1で検証するためのin vitroとin vivoの機能解析を行った。まずin vitro実験では、大腸菌で発現して精製したVIPP1-Hisタンパク質を用いたNTPase活性部位の解析と複合体構造の変化について、点突然変異を導入して検討した。シアノバクテリアでは、構造から明らかになったヌクレオチド結合部位に変異(E126Q/E179Q二重変異)を導入したところATPおよびGTPの加水分解活性が完全に失活していたが、シロイヌナズナに同じ変異を導入したところ、これらの加水分解活性が失活せず、むしろ野生型よりも高い活性を示すことが明らかになった。一方で、N末端側のαヘリックス内のアミノ酸、特に11番目のバリン残基にアミノ酸置換を加えたVIPP1タンパク質では活性が低下する変異が得られた。次にin vivoの実験では、シロイヌナズナvipp1ノックアウト変異(vipp1-ko)をVIPP1-GFPで相補する実験系を用いて、同様のアミノ酸変異を導入することとした。今年度は上述した変異を導入したVIPP1-GFP遺伝子を作成してvipp1-ko変異体ヘテロ個体を形質転換する実験が全て完了した。来年度以降、ホモ個体を選抜しin vitroでの結果を検証する。さらに、チラコイド膜内におけるリモデリング分子VIPP1, CURT1およびFZLの膜内局在を調べたところ、VIPP1はストロマチラコイドに主局在する一方、VIPP1とCURT1はグラナマージンに局在することが確認された。

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  • Studies on the missing link between stay green and adaptation to environment

    Grant number:18K19343  2018.06 - 2020.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Research (Exploratory)

    Sakamoto Wataru

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    Grant amount:\6240000 ( Direct expense: \4800000 、 Indirect expense:\1440000 )

    Stay green is a physiological trait that is associated with nutrient redistribution during plant growth, but its precise role in adaptation to environmental stresses remain unclear. This study aims in genetically dissecting the missing link between stay green and its contribution to environments such as drought, in a large biomass crop sorghum. In this study, we employed Japanese landrace Takakibi, showing non-stay-green phenotype. A recombinant inbred population generated from the cross between Takakibi and stay-green BTx623 was used to characterize QTL associated with leaf greenness under natural growing condition. The linkage analysis allowed us to identify one QTL in chromosome 5. This gene appeared to be deleted in Takakibi, and we further investigated this gene as to whether it is responsible for the stay green trait.

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Class subject in charge

  • Advances in Plant Stress Science (2024academic year) Late  - 水1~4

  • Model Plant Genetics and Breeding (2024academic year) Prophase  - 水1~4

  • Plant Physiology and Genetics (2024academic year) Prophase  - その他

  • Plant Genetics and Physiology (2024academic year) 1st semester  - 木1,木2

  • Seminar in Plant Genetics and Physiology (2024academic year) Prophase  - その他

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