title: Novel Features of Eukaryotic Photosystem II Revealed by Its Crystal Structure Analysis from a Red Alga.
abstract: Photosystem II (PSII) catalyzes light-induced water splitting, leading to the evolution of molecular oxygen indispensible for life on the earth. The crystal structure of PSII from cyanobacteria has been solved at an atomic level, but the structure of eukaryotic PSII has not been analyzed. Because eukaryotic PSII possesses additional subunits not found in cyanobacterial PSII, it is important to solve the structure of eukaryotic PSII to elucidate their detailed functions, as well as evolutionary relationships. Here we report the structure of PSII from a red alga Cyanidium caldarium at 2.76 Å resolution, which revealed the structure and interaction sites of PsbQ', a unique, fourth extrinsic protein required for stabilizing the oxygen-evolving complex in the lumenal surface of PSII. The PsbQ' subunit was found to be located underneath CP43 in the vicinity of PsbV, and its structure is characterized by a bundle of four up-down helices arranged in a similar way to those of cyanobacterial and higher plant PsbQ, although helices I and II of PsbQ' were kinked relative to its higher plant counterpart because of its interactions with CP43. Furthermore, two novel transmembrane helices were found in the red algal PSII that are not present in cyanobacterial PSII; one of these helices may correspond to PsbW found only in eukaryotic PSII. The present results represent the first crystal structure of PSII from eukaryotic oxygenic organisms, which were discussed in comparison with the structure of cyanobacterial PSII.
authors.affiliation: From the RIKEN SPring-8 Center, Hyogo 679-5148, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Ago
authors.affiliation: the Photosynthesis Research Center, Graduate School of Natural Science and Technology/Faculty of Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Adachi
authors.affiliation: the Osaka City University Advanced Research Institute for Natural Science and Technology (OCARNA), Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan,; the Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Tokyo 102-0076, Japan.
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Umena
authors.affiliation: the Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi, Osaka 558-8585, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Tashiro
authors.affiliation: the Osaka City University Advanced Research Institute for Natural Science and Technology (OCARNA), Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kawakami
authors.affiliation: the Osaka City University Advanced Research Institute for Natural Science and Technology (OCARNA), Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan,; the Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi, Osaka 558-8585, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kamiya
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Lirong
authors.initials: L
authors.lastname: Tian
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Guangye
authors.initials: G
authors.lastname: Han
authors.affiliation: the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Tingyun
authors.initials: T
authors.lastname: Kuang
authors.affiliation: the Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China and.
authors.forename: Zheyi
authors.initials: Z
authors.lastname: Liu
authors.affiliation: the Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China and.
authors.forename: Fangjun
authors.initials: F
authors.lastname: Wang
authors.affiliation: the Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China and.
authors.forename: Hanfa
authors.initials: H
authors.lastname: Zou
authors.affiliation: the Department of Biology, Faculty of Science, Tokyo University of Science, Shinjuku-ku, Tokyo 162-8601, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Enami
authors.affiliation: From the RIKEN SPring-8 Center, Hyogo 679-5148, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyano
authors.affiliation: the Photosynthesis Research Center, Graduate School of Natural Science and Technology/Faculty of Science, Okayama University, Okayama 700-8530, Japan,; the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China,. Electronic address: shen@cc.okayama-u.ac.jp.
authors.forename: Jian-Ren
authors.initials: JR
authors.lastname: Shen
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000648:ultrastructure; D010940:Plant Proteins / Q000737:chemistry* / Q000648:ultrastructure; D011487:Protein Conformation; D055503:Protein Multimerization; D000461:Rhodophyta / Q000737:chemistry*; D016415:Sequence Alignment
chemical_list: D045332:Photosystem II Protein Complex; D010940:Plant Proteins
keywords: crystal structure; crystallography; cyanobacteria; electron transfer complex; membrane protein; photosynthesis; photosystem II; x-ray crystallography