研究者詳細 - 齊藤　恭紀

論文 - 齊藤　恭紀

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The hidden cation-selective pore in ion-conducting aquaporin OsPIP2;4 from rice 査読

Shuntaro Ono, Sen Thi Huong Tran, Yasunori Saitoh, Shigeko Utsugi, Tomoaki Horie, Maki Katsuhara

Plant Physiology and Biochemistry 2025年6月

Biosensor Application of CMOS Inverter and Ring Oscillator with Organic Field-Effect Transistors 査読

Masaki Utsumi, Akihiko Fujiwara, Hidenori Goto, Hideki Okamoto, Nobuyuki Takeyasu, Yasunori Saitoh, Michihiro Suga, Yuichiro Takahashi, Hiroyuki Imanaka, Hiroki Taniguchi, Shintaro Yasui, Ritsuko Eguchi, Yoshihiro Kubozono

ACS Applied Electronic Materials 7 ( 4 ) 1483 - 1492 2025年2月

Shoot-Silicon-Signal protein to regulate root silicon uptake in rice 査読

Naoki Yamaji, Namiki Mitani-Ueno, Toshiki Fujii, Tomonori Shinya, Ji Feng Shao, Shota Watanuki, Yasunori Saitoh, Jian Feng Ma

Nature Communications 15 ( 10712 ) 1 - 11 2024年12月

Oxygen-evolving photosystem II structures during S1–S2–S3 transitions 査読

Hongjie Li, Yoshiki Nakajima, Eriko Nango, Shigeki Owada, Daichi Yamada, Kana Hashimoto, Fangjia Luo, Rie Tanaka, Fusamichi Akita, Koji Kato, Jungmin Kang, Yasunori Saitoh, Shunpei Kishi, Huaxin Yu, Naoki Matsubara, Hajime Fujii, Michihiro Sugahara, Mamoru Suzuki, Tetsuya Masuda, Tetsunari Kimura, Tran Nguyen Thao, Shinichiro Yonekura, Long-Jiang Yu, Takehiko Tosha, Kensuke Tono, Yasumasa Joti, Takaki Hatsui, Makina Yabashi, Minoru Kubo, So Iwata, Hiroshi Isobe, Kizashi Yamaguchi, Michihiro Suga, Jian-Ren Shen

Nature 626 ( 7999 ) 670 - 677 2024年1月

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 Science and Business Media LLC

Abstract

Photosystem II (PSII) catalyses the oxidation of water through a four-step cycle of S_i states (i = 0–4) at the Mn₄CaO₅ cluster^1–3, during which an extra oxygen (O6) is incorporated at the S₃ state to form a possible dioxygen^4–7. Structural changes of the metal cluster and its environment during the S-state transitions have been studied on the microsecond timescale. Here we use pump-probe serial femtosecond crystallography to reveal the structural dynamics of PSII from nanoseconds to milliseconds after illumination with one flash (1F) or two flashes (2F). Y_Z, a tyrosine residue that connects the reaction centre P680 and the Mn₄CaO₅ cluster, showed structural changes on a nanosecond timescale, as did its surrounding amino acid residues and water molecules, reflecting the fast transfer of electrons and protons after flash illumination. Notably, one water molecule emerged in the vicinity of Glu189 of the D1 subunit of PSII (D1-E189), and was bound to the Ca²⁺ ion on a sub-microsecond timescale after 2F illumination. This water molecule disappeared later with the concomitant increase of O6, suggesting that it is the origin of O6. We also observed concerted movements of water molecules in the O1, O4 and Cl-1 channels and their surrounding amino acid residues to complete the sequence of electron transfer, proton release and substrate water delivery. These results provide crucial insights into the structural dynamics of PSII during S-state transitions as well as O–O bond formation.

DOI： 10.1038/s41586-023-06987-5

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その他リンク： https://www.nature.com/articles/s41586-023-06987-5

植物のケイ酸チャネルの構造と機能招待査読

齊藤恭紀, 菅倫寛

日本結晶学会誌 64 ( 4 ) 265 - 266 2022年12月

Structure and function of a silicic acid channel Lsi1 招待査読国際誌

Yasunori Saitoh, Michihiro Suga

Frontiers in Plant Science 13 ( 982068 ) 1 - 9 2022年9月

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）

Silicon is a beneficial element for plant growth and production, especially in rice. Plant roots take up silicon in the form of silicic acid. Silicic acid channels, which belong to the NIP subfamily of aquaporins, are responsible for silicic acid uptake. Accumulated experimental results have deepened our understanding of the silicic acid channel for its uptake mechanism, physiological function, localization, and other aspects. However, how the silicic acid channel efficiently and selectively permeates silicic acid remains to be elucidated. Recently reported crystal structures of the silicic acid channel enabled us to discuss the mechanism of silicic acid uptake by plant roots at an atomic level. In this mini-review, we focus on the crystal structures of the silicic acid channel and provide a detailed description of the structural determinants of silicic acid permeation and its transport mechanism, which are crucial for the rational creation of secure and sustainable crops.

DOI： 10.3389/fpls.2022.982068

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Structural basis for high selectivity of a rice silicon channel Lsi1 査読国際誌

Yasunori Saitoh, Namiki Mitani-Ueno, Keisuke Saito, Kengo Matsuki, Sheng Huang, Lingli Yang, Naoki Yamaji, Hiroshi Ishikita, Jian-Ren Shen, Jian Feng Ma, Michihiro Suga

Nature Communications 12 ( 1 ) 6236 - 6236 2021年10月

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 Science and Business Media LLC

<title>Abstract</title>Silicon (Si), the most abundant mineral element in the earth’s crust, is taken up by plant roots in the form of silicic acid through Low silicon rice 1 (Lsi1). Lsi1 belongs to the Nodulin 26-like intrinsic protein subfamily in aquaporin and shows high selectivity for silicic acid. To uncover the structural basis for this high selectivity, here we show the crystal structure of the rice Lsi1 at a resolution of 1.8 Å. The structure reveals transmembrane helical orientations different from other aquaporins, characterized by a unique, widely opened, and hydrophilic selectivity filter (SF) composed of five residues. Our structural, functional, and theoretical investigations provide a solid structural basis for the Si uptake mechanism in plants, which will contribute to secure and sustainable rice production by manipulating Lsi1 selectivity for different metalloids.

DOI： 10.1038/s41467-021-26535-x

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その他リンク： https://www.nature.com/articles/s41467-021-26535-x

Morphologic determinant of tight junctions revealed by claudin-3 structures. 査読国際誌

Shun Nakamura, Katsumasa Irie, Hiroo Tanaka, Kouki Nishikawa, Hiroshi Suzuki, Yasunori Saitoh, Atsushi Tamura, Sachiko Tsukita, Yoshinori Fujiyoshi

Nature communications 10 ( 1 ) 816 - 816 2019年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

Tight junction is a cell adhesion apparatus functioning as barrier and/or channel in the paracellular spaces of epithelia. Claudin is the major component of tight junction and polymerizes to form tight junction strands with various morphologies that may correlate with their functions. Here we present the crystal structure of mammalian claudin-3 at 3.6 Å resolution. The third transmembrane helix of claudin-3 is clearly bent compared with that of other subtypes. Structural analysis of additional two mutants with a single mutation representing other subtypes in the third helix indicates that this helix takes a bent or straight structure depending on the residue. The presence or absence of the helix bending changes the positions of residues related to claudin-claudin interactions and affects the morphology and adhesiveness of the tight junction strands. These results evoke a model for tight junction strand formation with different morphologies - straight or curvy strands - observed in native epithelia.

DOI： 10.1038/s41467-019-08760-7

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ウェルシュ菌エンテロトキシンとクローディン-19との複合体の構造学的研究査読

齊藤恭紀

名古屋大学大学院創薬科学研究科博士論文 2017年3月

Structural insight into tight junction disassembly by Clostridium perfringens enterotoxin 査読

Yasunori Saitoh, Hiroshi Suzuki, Kazutoshi Tani, Kouki Nishikawa, Katsumasa Irie, Yuki Ogura, Atsushi Tamura, Sachiko Tsukita, Yoshinori Fujiyoshi

SCIENCE 347 ( 6223 ) 775 - 778 2015年2月

Novel Vasotocin-Regulated Aquaporins Expressed in the Ventral Skin of Semiaquatic Anuran Amphibians: Evolution of Cutaneous Water-Absorbing Mechanisms 査読

Yasunori Saitoh, Yuji Ogushi, Yuki Shibata, Reiko Okada, Shigeyasu Tanaka, Masakazu Suzuki

ENDOCRINOLOGY 155 ( 6 ) 2166 - 2177 2014年6月

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