Phycobilin:: cystein-84 biliprotein lyase, a near-universal lyase for cysteine-84-binding sites in cyanobacterial phycobiliproteins
Phycobilin:: cystein-84 biliprotein lyase, a near-universal lyase for cysteine-84-binding sites in cyanobacterial phycobiliproteins
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DOI：
10.1073/pnas.0706209104
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发表时间：
2007-09-04
影响因子：
11.1
通讯作者：
Scheer, Hugo
中科院分区：
文献类型：
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作者：
Zhao, Kai-Hong;Su, Ping;Scheer, Hugo
藻胆体是蓝藻和红藻的捕光复合体，含有两到四种类型的发色团，它们共价连接到一个同源蛋白质家族的七个或更多成员上，每个成员携带一到四个结合位点。发色团与脱辅基蛋白的结合是由裂解酶催化的，其中只有很少的几种被详细描述。这种情况是复杂的非酶背景结合到一些载脂蛋白。利用大肠杆菌中的低背景结合的模块化多质粒表达-重建测定，来自鱼腥藻PCC 7120的藻胆素：半胱氨酸-84胆蛋白裂解酶（CpeS 1）已被表征为几乎通用的半胱氨酸-84结合位点的裂解酶，所述半胱氨酸-84结合位点在所有胆蛋白中保守。它催化藻蓝胆素与所有别藻蓝蛋白亚基以及C-藻蓝蛋白和藻红蓝蛋白的β-亚基中的半胱氨酸-84的共价连接。与已知的裂解酶一起，它可以解释发色团与鱼腥藻PCC 7120的藻胆蛋白的所有结合位点的结合。此外，它催化藻红胆素附着到C-藻红蛋白的两个亚基的半胱氨酸-84。在半胱氨酸-84位点中，CpeS 1不起作用的唯一例外是藻蓝蛋白和藻红蓝蛋白的α-亚基，通过序列分析，其已被定义为由更专门的E/F型裂解酶起作用的亚类的成员。
Phycobilisomes, the light-harvesting complexes of cyanobacteria and red algae, contain two to four types of chromophores that are attached covalently to seven or more members of a family of homologous proteins, each carrying one to four binding sites. Chromophore binding to apoproteins is catalyzed by lyases, of which only few have been characterized in detail. The situation is complicated by nonenzymatic background binding to some apoproteins. Using a modular multiplasmidic expression-reconstitution assay in Escherichia coli with low background binding, phycobilin:cystein-84 biliprotein lyase (CpeS1) from Anabaena PCC7120, has been characterized as a nearly universal lyase for the cysteine-84-binding site that is conserved in all biliproteins. It catalyzes covalent attachment of phycocyanobilin to all allophycocyanin subunits and to cysteine-84 in the beta-subunits of C-phycocyanin and phycoerythrocyanin. Together with the known lyases, it can thereby account for chromophore binding to all binding sites of the phycobiliproteins of Anabaena PCC7120. Moreover, it catalyzes the attachment of phycoerythrobilin to cysteine-84 of both subunits of C-phycoerythrin. The only exceptions not served by CpeS1 among the cysteine-84 sites are the alpha-subunits from phycocyanin and phycoerythrocyanin, which, by sequence analyses, have been defined as members of a subclass that is served by the more specialized E/F type lyases.