Chromophore organization in the higher-plant photosystem II antenna protein CP26
Chromophore organization in the higher-plant photosystem II antenna protein CP26
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DOI：
10.1021/bi0257437
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发表时间：
2002-06-11
期刊：
影响因子：
2.9
通讯作者：
Bassi, R
中科院分区：
文献类型：
--
作者：
Croce, R;Canino, G;Bassi, R
叶绿素a/b-叶黄素-蛋白质CP 26复合物属于Lhc蛋白质家族。每26.6 kDa多肽结合9个叶绿素和2个叶黄素。每个结合位点的特征的确定是需要的理解属于光系统II超分子复合物的单个蛋白质的功能组织。本文介绍了天然CP 26的生化和光谱特征，以及不同位点的色素结合和能量跃迁。分析已通过一种新的方法，使用重组CP 26复合物，其中的发色团含量已被实验修改。根据与CP 29和LHCII复合物的同源性解释数据，其详细知识可从突变分析中获得。我们建议，一个额外的Ch 1 B是目前在CP 26相比，CP 29，它位于网站B2。我们还发现，在CP 26三个叶绿素结合位点是选择性的Ch 1 a，其中之一是必不可少的折叠的色素蛋白质复合物。鉴定了两个叶黄素结合位点，其中之一（L1）是蛋白质折叠所必需的，并特异性结合叶黄素。第二个位点（L2）具有较低的选择性，可以结合类囊体中存在的任何叶黄素类。
The chlorophyll a/b-xanthophyll-protein CP26 complex belongs to the Lhc protein family. It binds nine chlorophylls and two xanthophylls per 26.6 kDa polypeptide. Determination of the characteristics of each binding site is needed for the understanding of functional organization of individual proteins belonging to the photosystem II supramolecular complex. The biochemical and spectroscopic features of native CP26 are presented here together with identification of pigment binding and energy transitions in different sites. The analysis has been performed via a new approach using recombinant CP26 complexes in which the chromophore content has been experimentally modified. Data were interpreted on the basis of homology with CP29 and LHCII complexes, for which detailed knowledge is available from mutation analysis. We propose that one additional Ch1 b is present in CP26 as compared to CP29 and that it is located in site B2. We also found that in CP26 three chlorophyll binding sites are selective for Ch1 a, one of them being essential for the folding of the pigment-protein complex. Two xanthophyll binding sites were identified, one of which (L1) is essential for protein folding and specifically binds lutein. The second site (L2) has lower selectivity and can bind any of the xanthophyll species present in thylakoids.