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

PubMed

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

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

DOI： 10.5940/jcrsj.64.265

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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）  

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

PubMed

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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 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

PubMed

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

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

PubMed

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J-GLOBAL

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J-GLOBAL

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開催年月日： 2024年11月7日 - 2024年11月8日

記述言語：日本語   会議種別：口頭発表（招待・特別）  

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開催年月日： 2023年12月13日

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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開催年月日： 2022年12月19日 - 2022年12月20日

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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開催年月日： 2022年11月11日

記述言語：日本語   会議種別：ポスター発表  

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開催年月日： 2022年6月7日 - 2022年6月9日

記述言語：英語   会議種別：口頭発表（招待・特別）  

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https://www.okayama-u.ac.jp/up_load_files/press_r5/press20240201-1.pdf

NHKニュース（全国放送），産経新聞（全国面），日刊工業新聞（全国面），山陽新聞（第1面），毎日新聞（地方面），読売新聞（全国Web），日経新聞（全国Web），YahooNews 等で報道

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山陽新聞デジタル, 山陽新聞2021年12月12日(日), 全県版第２全県

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BioArt植物

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日本経済新聞 オンライン

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Phys.org（２月１３日)

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