The hydrophobicity around the edge of the helix C of antenna protein of photosystem Ⅱ regulates its inter-molecular interaction in vitro
作者单位:Laboratory of photobiology Institute of Botany Chinese Academy of Sciences Institute of New Energy Technology Ningbo Industrial Technology Research Institute Chinese Academy of Sciences
会议名称:《第八届全国光生物学学术会议》
会议日期:2013年
学科分类:09[农学] 0903[农学-农业资源与环境]
基 金:supported by the State Key Basic Research and Development Plan of China (No.2009CB118501 and 2011CBA00904) the National Natural Science Foundation of China (No. 30800069 and 71070212)
关 键 词:The light harvesting chlorophyll a/b complexes of photosystem II luminal loop
摘 要:To avoid the damage to photosynthetic apparatus by excess illuminations, plants have developed a photoprotective mechanism called non-photochemical quenching(NPQ), where the light-harvesting chlorophyll a/b complex of photosystem II(LHCIIb) plays important roles. The structure of LHCIIb has been obtained at 2.72 A resolution from spinach and at 2.5 A resolution from pea [Standfuss et al, 2005;Liu et al, 2004], which lay down the basis for the study on the mechanisms of the structural and functional regulation. Further study revealed significance of the lumenal loop between transmembrane α-helices B/C of LHCIIb in regulating its structure and function under different conditions [Liu et al, 2008]. A series of mutational studies to LHCIIb have been conducted to illuminate the mechanisms of structural and functional regulation to LHCIIb. In this work, Ser123 in LHCIIb was mutated to Pro(SP), Thr(ST), Gln(SQ), Tyr(SY), and Gly(SG), and the structural and functional characteristics of different mutations was studied. Our results revealed that the structure of luminal loop is very important for pigment binding, for pigment conformational regulation, for inter-molecular interaction, and then for the functional regulation of the LHCIIb. Mutants SP and ST showed significant changes in the inter-molecular interaction, fluorescence efficiency and energy balance of the complexes, which reveals the importance of the hydrophobicity of the loop region in regulating the structure and function of the complexes.