title: Structural stability and properties of three isoforms of the major light-harvesting chlorophyll a/b complexes of photosystem II.
abstract: Three isoforms of the major light-harvesting chlorophyll (Chl) a/b complexs of photosystem II (LHCIIb) in the pea, namely, Lhcb1, Lhcb2, and Lhcb3, were obtained by overexpression of apoprotein in Escherichia coli and by successfully refolding these isoforms with thylakoid pigments in vitro. The sequences of the protein, pigment stoichiometries, spectroscopic characteristics, thermo- and photostabilities of different isoforms were analysed. Comparison of their spectroscopic properties and structural stabilities revealed that Lhcb3 differed strongly from Lhcb1 and Lhcb2 in both respects. It showed the lowest Qy transition energy, with its reddest absorption about 2 nm red-shifted, and the highest photostability under strong illuminations. Among the three isoforms, Lhcb 2 showed lowest thermal stability regarding energy transfer from Chl b to Chl a in the complexes, which implies that the main function of Lhcb 2 under high temperature stress is not the energy transfer.
authors.affiliation: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yajie
authors.initials: Y
authors.lastname: Zhang
authors.forename: Cheng
authors.initials: C
authors.lastname: Liu
authors.forename: Shuang
authors.initials: S
authors.lastname: Liu
authors.forename: Ye
authors.initials: Y
authors.lastname: Shen
authors.forename: Tingyun
authors.initials: T
authors.lastname: Kuang
authors.forename: Chunhong
authors.initials: C
authors.lastname: Yang
mesh_terms: D002734:Chlorophyll / Q000737:chemistry; D000077194:Chlorophyll A; D004926:Escherichia coli / Q000235:genetics; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000235:genetics; D018532:Pisum sativum / Q000201:enzymology* / Q000235:genetics; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D017510:Protein Folding; D020836:Protein Structure, Quaternary / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D020524:Thylakoids / Q000201:enzymology* / Q000235:genetics
chemical_list: D007527:Isoenzymes; D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011994:Recombinant Proteins; D002734:Chlorophyll; C037184:chlorophyll b; D000077194:Chlorophyll A