Electron-paramagnetic resonance (EPR) measurements for studying the assembly and structural dynamics of the light-harvesting chlorophyll a/b complex LHCII

主要捕光复合物（LHCII）是植物光合机构的主要组成部分，也是地球上最丰富的膜蛋白之一。电子顺磁共振（EPR）将用于测量LHCII在体外各种功能状态下的结构和结构动力学。由于LHCII可以在体外从其重组脱辅基蛋白组装，因此自旋标记物位点特异性地附着于蛋白质。因此，蛋白质结构可以通过测量标记的蛋白质结构域之间的距离或水可及性来表征。LHCII在各种功能状态下的结构将与其已知的晶体结构进行比较，回答LHCII是否在某些功能状态下表现出结构变化的问题。同样的方法将用于解开LHCII脱辅基蛋白在其与色素的体外自发组装过程中的折叠途径。这不仅有助于了解LHCII在植物中的生物发生，而且还产生关于膜蛋白折叠如何受到含有异常数量的辅因子的蛋白质中的辅因子结合的影响的信息。LHCII的生物发生将更紧密地模拟包括叶绿体信号识别颗粒（cpSRP）的蛋白质折叠的研究。

The major light-harvesting complex (LHCII) is a main component of the photosynthetic apparatus in plants and among the most abundant membrane proteins on Earth. Electronparamagnetic resonance (EPR) will be used to measure the structure and structural dynamics of LHCII in vitro in various functional states. Since LHCII can be assembled in vitro from its recombinant apoprotein, spin labels are site-specifically attached to the protein. Therefore, the protein structure can be characterized by measuring distances between or the water accessibility of labelled protein domains. The structure of LHCII in various functional states will be compared to its known crystal structure, answering the question of whether LHCII exhibits structural changes in some of these functional states. The same approach will be used unravel the folding pathway of the LHCII apoprotein during its spontaneous assembly with pigments in vitro. This will not only help to understand LHCII biogenesis in plants but also yield information about how membrane protein folding is influenced by cofactor binding in a protein containing an exceptional number of cofactors. LHCII biogenesis will be more closely modelled by including the chloroplast signal recognition particle (cpSRP) in the protein folding studies.