Two independent, light-sensing two-component systems in a filamentous cyanobacterium.
Two independent, light-sensing two-component systems in a filamentous cyanobacterium.
复制标题
丝状蓝藻中有两个独立的光传感双组分系统。
DOI：
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
W. Gärtner
中科院分区：
文献类型：
--
作者：
H. Jorissen;B. Quest;A. Remberg;T. Coursin;S. Braslavsky;K. Schaffner;N. T. de Marsac;W. Gärtner
两个开放阅读框CPHA和CphB编码的蛋白CPHA和CphB与植物光敏色素和聚球藻的蓝藻光敏色素Cph1有很强的相似性。在丝状蓝藻Calothrix sp.中已鉴定出PCC6803。PCC7601。虽然CPHA在一个高度保守的氨基酸序列基序中携带半胱氨酸，在植物光敏色素中生色团植物色动素与半胱氨酸共价结合，但在CphB中，这一位置被改变为亮氨酸。这两个ORF后面都跟随着RCPA和rcpB基因，它们编码的反应调节蛋白与细菌双组分信号转导中已知的类似。在Calothrix中，所有四个基因都在白光照射条件下表达，尽管数量很少。为了异源表达和方便纯化，克隆的基因在3‘端带有His-tag编码序列，并在大肠杆菌中进行了表达。这两个重组辅基蛋白CPHA和CphB分别以共价和非共价方式与发色团藻蓝胆素(PCb)结合，并经历了与植物光敏色素和Cph1的P(R)和P(Fr)形式(分别为红色和远红吸收形式)类似的光致变色吸收变化。CphB/PCB络合物的吸收峰红移(P(R)和P(Fr)的lambda(Max)分别为685和735 nm)表明生色团的非共价掺入(P(R)的lambda(Max)，CPHA的P(Fr)：663,700 nm)。在发色团结合位置产生的CphB突变体(Leu246->；Cys)与发色团共价结合，并显示出与其类似的CPHA的吸收光谱，表明非共价结合是CphB意外吸收性质的唯一原因。CPHA-PCB光诱导显色蛋白形成P(Fr)的动力学与聚球藻的同源蛋白相似，但形成P(Fr)的动力学有所不同。动力学不受ATP(自动磷酸化探针法)或反应调节剂的影响。相反，CphB-PCB复合体的光诱导动力学明显不同，这显然是由于非共价结合的发色团所致。
Two ORFs, cphA and cphB, encoding proteins CphA and CphB with strong similarities to plant phytochromes and to the cyanobacterial phytochrome Cph1 of Synechocystis sp. PCC 6803 have been identified in the filamentous cyanobacterium Calothrix sp. PCC7601. While CphA carries a cysteine within a highly conserved amino-acid sequence motif, to which the chromophore phytochromobilin is covalently bound in plant phytochromes, in CphB this position is changed into a leucine. Both ORFs are followed by rcpA and rcpB genes encoding response regulator proteins similar to those known from the bacterial two-component signal transduction. In Calothrix, all four genes are expressed under white light irradiation conditions, albeit in low amounts. For heterologous expression and convenient purification, the cloned genes were furnished with His-tag encoding sequences at their 3' end and expressed in Escherichia coli. The two recombinant apoproteins CphA and CphB bound the chromophore phycocyanobilin (PCB) in a covalent and a noncovalent manner, respectively, and underwent photochromic absorption changes reminiscent of the P(r) and P(fr) forms (red and far-red absorbing forms, respectively) of the plant phytochromes and Cph1. A red shift in the absorption maxima of the CphB/PCB complex (lambda(max) = 685 and 735 nm for P(r) and P(fr), respectively) is indicative for a noncovalent incorporation of the chromophore (lambda(max) of P(r), P(fr) of CphA: 663, 700 nm). A CphB mutant generated at the chromophore-binding position (Leu246-->Cys) bound the chromophore covalently and showed absorption spectra very similar to its paralog CphA, indicating the noncovalent binding to be the only cause for the unexpected absorption properties of CphB. The kinetics of the light-induced P(fr) formation of the CphA-PCB chromoprotein, though similar to that of its ortholog from Synechocystis, showed differences in the kinetics of the P(fr) formation. The kinetics were not influenced by ATP (probing for autophosphorylation) or by the response regulator. In contrast, the light-induced kinetics of the CphB-PCB complex was markedly different, clearly due to the noncovalently bound chromophore.
影响因子：
56.9
作者：
Yeh, KC;Wu, SH;Lagarias, JC
通讯作者：
Lagarias, JC
绿光诱导蓝藻 Calothrix 7601 中藻红蛋白操纵子的转录。
影响因子：
14.9
作者：
Mazel,D;Guglielmi,G;Houmard,J;Sidler,W;Bryant,DA;TandeaudeMarsac,N
通讯作者：
TandeaudeMarsac,N