Cyanobacteriochrome CcaS is the green light receptor that induces the expression of phycobilisome linker protein
Cyanobacteriochrome CcaS is the green light receptor that induces the expression of phycobilisome linker protein
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DOI：
10.1073/pnas.0801826105
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发表时间：
2008-07-15
影响因子：
11.1
通讯作者：
Ikeuchi, Masahiko
中科院分区：
文献类型：
--
作者：
Hirose, Yuu;Shimada, Takashi;Ikeuchi, Masahiko
蓝藻色素是一组新认识的光感受器，是光敏色素的不同亲戚，但只在蓝藻中发现。已知一种假定的蓝藻色素CcaS可以从颜色上调控藻胆酶体连接基因（cpcG2）在Synechocystis sp. PCC 6803中的表达。在这项研究中，我们从聚胞菌和产藻蓝胆素的大肠杆菌中分离出CcaS的发色团结合结构域。两种材料在绿色吸收形式（Pg, λ (max) = 535 nm）和红色吸收形式（Pr, λ (max) = 672 nm）之间表现出相同的可逆光转换。质谱分析和变性分析表明，Pg和Pr分别以C15-Z和C15-E的双键构型与藻蓝胆素结合。绿光预照射可上调近全长CcaS组氨酸激酶域的自磷酸化活性。同样，向同源反应调节因子CcaR的磷酸化在Pr中比在Pg中更高。根据这些结果，我们得出结论，CcaS在绿光下磷酸化CcaR并诱导cpcG2的表达，导致cpcG2 -藻脂体的积累，作为一个色化驯化系统。CcaS是扩展光敏色素超家族中第一个被认可的绿光受体，该家族包括光敏色素和蓝藻色素。
Cyanobacteriochromes are a newly recognized group of photoreceptors that are distinct relatives of phytochromes but are found only in cyanobacteria. A putative cyanobacteriochrome, CcaS, is known to chromatically regulate the expression of the phycobilisome linker gene (cpcG2) in Synechocystis sp. PCC 6803. In this study, we isolated the chromophore-binding domain of CcaS from Synechocystis as well as from phycocyanobilin-producing Escherichia coli. Both preparations showed the same reversible photoconversion between a green-absorbing form (Pg, lambda(max) = 535 nm) and a red-absorbing form (Pr, lambda(max) = 672 nm). Mass spectrometry and denaturation analyses suggested that Pg and Pr bind phycocyanobilin in a double-bond configuration of C15-Z and C15-E, respectively. Auto phosphorylation activity of the histidine kinase domain in nearly full-length CcaS was up-regulated by preirradiation with green light. Similarly, phosphotransfer to the cognate response regulator, CcaR, was higher in Pr than in Pg. From these results, we conclude that CcaS phosphorylates CcaR under green light and induces expression of cpcG2, leading to accumulation of CpcG2-phycobilisome as a chromatic acclimation system. CcaS is the first recognized green light receptor in the expanded phytochrome superfamily, which includes phytochromes and cyanobacteriochromes.