title: Isolation and characterization of PSI-LHCI super-complex and their sub-complexes from a red alga Cyanidioschyzon merolae.
abstract: Photosystem I (PSI)-light-harvesting complex I (LHCI) super-complex and its sub-complexes PSI core and LHCI, were purified from a unicellular red alga Cyanidioschyzon merolae and characterized. PSI-LHCI of C. merolae existed as a monomer with a molecular mass of 580 kDa. Mass spectrometry analysis identified 11 subunits (PsaA, B, C, D, E, F, I, J, K, L, O) in the core complex and three LHCI subunits, CMQ142C, CMN234C, and CMN235C in LHCI, indicating that at least three Lhcr subunits associate with the red algal PSI core. PsaG was not found in the red algae PSI-LHCI, and we suggest that the position corresponding to Lhca1 in higher plant PSI-LHCI is empty in the red algal PSI-LHCI. The PSI-LHCI complex was separated into two bands on native PAGE, suggesting that two different complexes may be present with slightly different protein compositions probably with respective to the numbers of Lhcr subunits. Based on the results obtained, a structural model was proposed for the red algal PSI-LHCI. Furthermore, pigment analysis revealed that the C. merolae PSI-LHCI contained a large amount of zeaxanthin, which is mainly associated with the LHCI complex whereas little zeaxanthin was found in the PSI core. This indicates a unique feature of the carotenoid composition of the Lhcr proteins and may suggest an important role of Zea in the light-harvesting and photoprotection of the red algal PSI-LHCI complex.
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.|University of Chinese Academy of Sciences, Yuquan Rd, Shijingshan District, Beijing, 100049, China.
authors.forename: Lirong
authors.initials: L
authors.lastname: Tian
authors.affiliation: Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China.
authors.forename: Zheyi
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China.
authors.forename: Fangjun
authors.initials: F
authors.lastname: Wang
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.|University of Chinese Academy of Sciences, Yuquan Rd, Shijingshan District, Beijing, 100049, China.
authors.forename: Liangliang
authors.initials: L
authors.lastname: Shen
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.|University of Chinese Academy of Sciences, Yuquan Rd, Shijingshan District, Beijing, 100049, China.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Chen
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.|University of Chinese Academy of Sciences, Yuquan Rd, Shijingshan District, Beijing, 100049, China.
authors.forename: Lijing
authors.initials: L
authors.lastname: Chang
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.|University of Chinese Academy of Sciences, Yuquan Rd, Shijingshan District, Beijing, 100049, China.
authors.forename: Songhao
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.
authors.forename: Guangye
authors.initials: G
authors.lastname: Han
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.
authors.forename: Wenda
authors.initials: W
authors.lastname: Wang
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China.
authors.forename: Tingyun
authors.initials: T
authors.lastname: Kuang
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China. bio_qinxc@ujn.edu.cn.|School of Biological Science and Technology, University of Jinan, No.336, Nanxinzhuang West Road, Jinan, 250022, China. bio_qinxc@ujn.edu.cn.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Qin
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20, Nanxincun, Xiangshan, Beijing, 100093, China. shen@cc.okayama-u.ac.jp.|Research Institute of Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima Naka 3-1-1, Okayama, 700-8530, Japan. shen@cc.okayama-u.ac.jp.
authors.forename: Jian-Ren
authors.initials: JR
authors.lastname: Shen
mesh_terms: D000595:Amino Acid Sequence; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D045331:Photosystem I Protein Complex / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D010860:Pigments, Biological / Q000378:metabolism; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D000461:Rhodophyta / Q000378:metabolism*; D016415:Sequence Alignment; D013050:Spectrometry, Fluorescence
chemical_list: D045342:Light-Harvesting Protein Complexes; D010455:Peptides; D045331:Photosystem I Protein Complex; D010860:Pigments, Biological; D021122:Protein Subunits; D010100:Oxygen
keywords: Cyanidioschyzon merolae; Light-harvesting; PSI–LHCI; Red algae; Zeaxanthin