Light-induced structural changes and the site of O=O bond formation in PSII caught by XFEL.Suga, M., Akita, F., Sugahara, M., Kubo, M., Nakajima, Y., Nakane, T., Yamashita, K., Umena, Y., Nakabayashi, M., Yamane, T., Nakano, T., Suzuki, M., Masuda, T., Inoue, S., Kimura, T., Nomura, T., Yonekura, S., Yu, L.J., Sakamoto, T., Motomura, T., Chen, J.H., Kato, Y., Noguchi, T., Tono, K., Joti, Y., Kameshima, T., Hatsui, T., Nango, E., Tanaka, R., Naitow, H., Matsuura, Y., Yamashita, A., Yamamoto, M., Nureki, O., Yabashi, M., Ishikawa, T., Iwata, S., Shen, J.R.
(2017) Nature 543: 131-135
- PubMed: 28219079
- DOI: 10.1038/nature21400
- Primary Citation of Related Structures:
- PubMed Abstract:
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). T ...
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 Mn 4 CaO 5 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 Q B /non-haem iron and the Mn 4 CaO 5 cluster. The changes around the Q B /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 Mn 4 CaO 5 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 μ 4 -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.
Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.,Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.,Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, Beijing 100093, China.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.,Department of Picobiology, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan.,Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.,Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.,Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima Naka, Okayama 700-8530, Japan.,Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.,Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka 565-0871, Japan.,Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.