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

主要捕光复合体(LHCII)是植物光合作用装置的主要组成部分，也是地球上含量最丰富的膜蛋白之一。电子顺磁共振(EPR)将被用来测量体外LHCII在不同功能状态下的结构和结构动力学。由于LHCII可以从其重组的载脂蛋白在体外组装，因此自旋标记被特异性地附着在蛋白质上。因此，可以通过测量标记蛋白质结构域之间的距离或水的可及性来表征蛋白质结构。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，以回答LHCII在其中一些功能状态下是否表现出结构变化的问题。同样的方法将被用来解开LHCII载脂蛋白在体外与色素自发组装时的折叠途径。这不仅有助于了解LHCII在植物中的生物发生，而且还提供了关于膜蛋白折叠如何受到含有大量辅因子的蛋白质中辅因子结合的影响的信息。通过将叶绿体信号识别颗粒(CpSRP)包括在蛋白质折叠研究中，LHCII的生物发生将被更紧密地模拟。

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.