隐花色素CRY2介导蓝光调控植物生物钟节律的分子机制研究

Circadian clock regulation is an important endogenous mechanism in plant, which bears the basic characteristics of life. In order to adapt with the constantly changing surroundings, plant senses the environmental signal and regulates the rhythm of core oscillator via series of receptors. Since the key gene of the light –circadian clock regulation system has not been identified, the mechanism of light –circadian clock regulation system remains unknown. In contrast, the mechanisms of core oscillator and blue light signal transduction have been well studied, respectively. Recently, we have found that PPK1, kinase of CRY2, could phosphorylate the transcription factor TCP20 and TCP22 via the interaction of PPK1-TCP20 and PPK1-TCP22, respectively. Meanwhile according to our studies, the phosphorylation of TCP22 and the transcription of CCA1 are regulated by CRY2 in a blue light dependent manner. Those results provide an important clue for the study of light–circadian clock regulation system. In this study, we propose to analyze the protein-protein interaction around cryptochromes, PPKs and TCPs. Simultaneously, this study proposes to investigate the mechanisms of the related enzyme reactions and the mechanism of light–circadian clock regulation system. This study is aim to elucidate how blue light modulate the rhythm of circadian clocks.

生物钟是重要的植物内源调控系统，也是生物体的重要基本特征之一。植物通过受体感知外界环境信号，并校正生物钟节律，使其适应环境变化。由于与蓝光信号输入生物钟系统相关的关键基因没有找到，虽然目前对植物生物钟中心振荡器及蓝光信号传导的分子机制分别已有了较为深入的研究，然而蓝光信号如何输入中心振荡器并调控其节律的重要科学问题却鲜有研究，对其认知几乎停留在20年前。我们最近发现CRY2的激酶PPK1能与生物钟相关的转录因子TCP20、TCP22相互作用，并使其磷酸化。与此同时，CRY2能间接地调控TCP22的磷酸化程度及CCA1的转录表达。这些发现为研究蓝光输入、调控生物钟的分子机制提供了重要理论依据。在此基础上，本项目拟对隐花色素、PPKs、TCPs之间的互作关系及相关酶反应机制开展深入的研究，进而解析CRY2如何介导蓝光调控植物生物钟节律的分子机制，以阐明蓝光输入、调控植物生物钟的重要科学问题。

生物钟调控了植物诸多生理反应，是植物适应环境和生长发育重要的调控机制。光信号是植物调控其内在生物钟的重要环境因子之一。植物通过光受体感受外界光信号以调控其生物钟的节律。虽然在上世纪就发现了光受体可以调控植物的生物钟节律，但光受体如何将光信号输入生物钟的具体生物机制确一直未能阐明。本项目通过研究植物蓝光受体CRY2以及其相互作用蛋白，解析了植物光受体如何介导蓝光调控植物生物钟节律的具体分子机制，研究主要包括了：1.解析了植物蓝光受体CRY2不仅行驶光受体功能，在植物体内还具有转录增强子的功能；2。揭示了CRY2能与TCP22，LWD1，LWD2以及激酶PPK1形成蛋白复合体，并在蓝光下激活植物生物钟中心振荡器CCA1的转录水平，从而调控植物生物钟节律的具体分子机制；3. 发现CRY2与TCP22等蛋白能够在蓝光的刺激下形成相分离，从而进一步激活CCA1的转录，这也是首次发现光受体通过相分离的形式，调控植物生物钟节律的分子机制。