title: Evidence for dissociation of chlorophyll b from the main light-harvesting complex in the oligomerization state isolated from marine alga, Bryopsis corticulans.
abstract: We investigated the composition and organization of chlorophylls in monomers, trimers and oligomers (small aggregates) of the main light-harvesting complex (LHC II) isolated from marine alga, Bryopsis corticulans, using a combination of measurements with reversed-phase high performance liquid chromatography (RP-HPLC) and steady-state spectroscopy of absorption, circular dichroism (CD) and low temperature fluorescence. The composition and organization of the chlorophylls in monomeric and trimeric LHC II were essentially identical to those of LHC II from higher plants. For LHC II oligomers, a large decrease of chlorophyll (Chl) b absorption and of CD signals corresponding to Chl b was consistent with the quantitative analysis of Chl b by RP-HPLC, indicating that oligomerization of the LHC II proteins significantly influenced spectroscopic properties and led to the dissociation of Chl b molecules from LHC II. Our data strongly suggested that protein oligomerization constitutes a structural basis for the decrease of Chl b molecules in LHC II of B. corticulans. The LHC II of B. corticulans might play a photoprotective role with the reduction of the ability of light absorption via alteration of its own structural conformation.
authors.affiliation: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Beijing 100093, China. chenh@ibcas.ac.cn
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Shihua
authors.initials: S
authors.lastname: Shen
authors.forename: Yu
authors.initials: Y
authors.lastname: Liang
authors.forename: Jing
authors.initials: J
authors.lastname: Leng
authors.forename: Mingjuan
authors.initials: M
authors.lastname: Tang
authors.forename: Yandao
authors.initials: Y
authors.lastname: Gong
mesh_terms: D000595:Amino Acid Sequence; D002734:Chlorophyll / Q000737:chemistry*; D000460:Chlorophyta / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000302:isolation & purification; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000302:isolation & purification; D013057:Spectrum Analysis
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; C037184:chlorophyll b