フルテキストURL Nature_543_7643_131.pdf
著者 Suga, Michihiro| Akita, Fusamichi| Sugahara, Michihiro| Kubo, Minoru| Nakajima, Yoshiki| Nakane, Takanori| Yamashita, Keitaro| Umena, Yasufumi| Nakabayashi, Makoto| Yamane, Takahiro| Nakano, Takamitsu| Suzuki, Mamoru| Masuda, Tetsuya| Inoue, Shigeyuki| Kimura, Tetsunari| Nomura, Takashi| Yonekura, Shinichiro| Yu, Long-Jiang| Sakamoto, Tomohiro| Motomura, Taiki| Chen, Jing-Hua| Kato, Yuki| Noguchi, Takumi| Tono, Kensuke| Joti, Yasumasa| Kameshima, Takashi| Hatsui, Takaki| Nango, Eriko| Tanaka, Rie| Naitow, Hisashi| Matsuura, Yoshinori| Yamashita, Ayumi| Yamamoto, Masaki| Nureki, Osamu| Yabashi, Makina| Ishikawa, Tetsuya| Iwata, So| Shen, Jian-Ren|
抄録 Photosystem II (PSII) is a huge membrane-protein complex consisting of 20 different subunits with a total molecular mass of 350 kDa for a monomer. It catalyses light-driven water oxidation at its catalytic centre, the oxygen-evolving complex (OEC). The structure of PSII has been analysed at 1.9 Å resolution by synchrotron radiation X-rays, which revealed that the OEC is a Mn4CaO5 cluster organized in an asymmetric, 'distorted-chair' form. This structure was further analysed with femtosecond X-ray free electron lasers (XFEL), providing the 'radiation damage-free' structure. The mechanism of O=O bond formation, however, remains obscure owing to the lack of intermediate-state structures. Here we describe the structural changes in PSII induced by two-flash illumination at room temperature at a resolution of 2.35 Å using time-resolved serial femtosecond crystallography with an XFEL provided by the SPring-8 ångström compact free-electron laser. An isomorphous difference Fourier map between the two-flash and dark-adapted states revealed two areas of apparent changes: around the QB/non-haem iron and the Mn4CaO5 cluster. The changes around the QB/non-haem iron region reflected the electron and proton transfers induced by the two-flash illumination. In the region around the OEC, a water molecule located 3.5 Å from the Mn4CaO5 cluster disappeared from the map upon two-flash illumination. This reduced the distance between another water molecule and the oxygen atom O4, suggesting that proton transfer also occurred. Importantly, the two-flash-minus-dark isomorphous difference Fourier map showed an apparent positive peak around O5, a unique μ4-oxo-bridge located in the quasi-centre of Mn1 and Mn4 (refs 4,5). This suggests the insertion of a new oxygen atom (O6) close to O5, providing an O=O distance of 1.5 Å between these two oxygen atoms. This provides a mechanism for the O=O bond formation consistent with that proposed previously
発行日 2017-03
出版物タイトル Nature
543巻
7643号
出版者 Nature Publishing Group
開始ページ 131
終了ページ 135
ISSN 0028-0836
NCID AA00752384
資料タイプ 学術雑誌論文
言語 English
OAI-PMH Set 岡山大学
著作権者 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.ja
論文のバージョン author
PubMed ID 28219079
DOI 10.1038/nature21400
Web of Sience KeyUT 000395671500047
関連URL https://doi.org/10.1038/nature21400