The pseudo-receiver domain of CikA regulates the cyanobacterial circadian input pathway
The pseudo-receiver domain of CikA regulates the cyanobacterial circadian input pathway
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DOI：
10.1111/j.1365-2958.2006.05138.x
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发表时间：
2006-05-01
影响因子：
3.6
通讯作者：
Golden, SS
中科院分区：
文献类型：
--
作者：
Zhang, XF;Dong, GG;Golden, SS
CikA（昼夜节律输入激酶）是蓝藻生物钟的一个组成部分，有助于使内源性振荡器与外部环境同步。原核昼夜节律模型生物细长聚球藻 PCC 7942 的 cikA 突变体在环境时间提示后无法重置基因表达的昼夜节律相位，并且还表现出昼夜节律振荡幅度降低和周期缩短。 CikA 具有组氨酸蛋白激酶 (HPK) 活性，该活性在体外受 GAF 和伪接收器 (PsR) 结构域调节。在这里，我们表明 PsR 结构域负向调节体内 HPK 活性，并且还充当将 CikA 停靠在特定亚细胞位置的相互作用模块。编码 CikA 变体的等位基因赋予的表型表明，除了无特征的 N 末端之外的所有结构域都是 CikA 功能所必需的。编码 PsR 结构域的所有等位基因的过度表达，无论 HPK 是否有功能，都会引起显性心律失常表型，而缺乏 PsR 的过度表达变体则不会。完整 CikA 的亚细胞定位确定了极焦点，而没有 PsR 的变体在细胞中显示出均匀分布，这与 PsR 介导与其他输入通路组件相互作用的模型一致。
CikA (circadian input kinase) is a component of the cyanobacterial circadian clock that aids in synchronizing the endogenous oscillator with the external environment. cikA mutants of the prokaryotic circadian model organism Synechococcus elongatus PCC 7942 fail to reset the phase of the circadian rhythm of gene expression after an environmental time cue, and also exhibit reduced amplitude and shortened period of circadian oscillation. CikA has histidine protein kinase (HPK) activity that is modulated in vitro by GAF and pseudo-receiver (PsR) domains. Here we show that the PsR domain negatively regulates HPK activity in vivo and also serves as an interaction module to dock CikA at a specific subcellular location. Phenotypes conferred by alleles that encode CikA variants showed that all domains except the featureless N-terminus are required for CikA function. Overexpression of all alleles that encode the PsR domain, whether or not the HPK is functional, caused a dominant arrhythmic phenotype, whereas overexpressed variants that lack PsR did not. Subcellular localization of intact CikA identified a polar focus whereas a variant without PsR showed uniform distribution in the cell, consistent with a model in which PsR mediates interaction with other input pathway components.