Native structure of photosystem II at 1.95 angstrom resolution viewed by femtosecond X-ray pulses

• Suga, Michihiro

• Akita, Fusamichi

• Hirata, Kunio

• Ueno, Go

• Murakami, Hironori

• Nakajima, Yoshiki

• Shimizu, Tetsuya

• Yamashita, Keitaro

• Yamamoto, Masaki

• Ago, Hideo

• Shen, Jian-Ren

書誌事項

タイトル別名

• Native structure of photosystem II at 1.95 Å resolution viewed by femtosecond X-ray pulses
• Native structure of Photosystem II at 1.95A resolution viewed by femtosecond X-ray pulses
• Native Structure of Photosystem II at a 1.95 Å Resolution Viewed by Femotosecond X-ray Pulses

抄録

Photosynthesis converts light energy into biologically useful chemical energy vital to life on Earth. The initial reaction of photosynthesis takes place in photosystem II (PSII), a 700-kilodalton homodimeric membrane protein complex which catalyses photo-oxidation of water into dioxygen through an S-state cycle of the oxygen evolving complex (OEC). The structure of PSII has been solved by X-ray diffraction (XRD) at 1.9-ångström (Å) resolution, which revealed that the OEC is a Mn4CaO5-cluster coordinated by a well-defined protein environment1. However, extended X-ray absorption fine structure (EXAFS) studies showed that the manganese cations in the OEC are easily reduced by X-ray irradiation2, and slight differences were found in the Mn–Mn distances between the results of XRD1, EXAFS3–7 and theoretical studies8–14. Here we report a ‘radiation-damage-free’ structure of PSII from Thermosynechococcus vulcanus in the S1 state at a resolution of 1.95 Å using femtosecond X-ray pulses of the SPring-8 ångström compact free-electron laser (SACLA) and a huge number of large, highly isomorphous PSII crystals. Compared with the structure from XRD, the OEC in the X-ray free electron laser structure has Mn–Mn distances that are shorter by 0.1–0.2 Å. The valences of each manganese atom were tentatively assigned as Mn1D(III), Mn2C(IV), Mn3B(IV) and Mn4A(III), based on the average Mn–ligand distances and analysis of the Jahn–Teller axis on Mn(III). One of the oxo-bridged oxygens, O5, has significantly longer Mn–O distances in contrast to the other oxo-oxygen atoms, suggesting that it is a hydroxide ion instead of a normal oxygen dianion and therefore may serve as one of the substrate oxygen atoms. These findings provide a structural basis for the mechanism of oxygen evolution, and we expect that this structure will provide a blueprint for design of artificial catalysts for water oxidation.

収録刊行物

• Nature

  Nature 517 99-103, 2015-01-01

  Nature Publishing Group

キーワード

• Multidisciplinary

詳細情報

• CRID: 1050283687312788736
• NII論文ID: 120005656446
• NII書誌ID: AA00752384
• ISSN: 00280836
• ISSN: 14764687
• ISSN: http://id.crossref.org/issn/00280836
• DOI: 10.1038/nature13991
• Web Site: https://ousar.lib.okayama-u.ac.jp/53637
• Web Site: http://www.nature.com/articles/nature13991.pdf
• Web Site: http://www.nature.com/articles/nature13991
• 本文言語コード: en
• 資料種別: journal article
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