The signaling mechanisms of Arabidopsis CRY2

摘要 细胞如何对光和/或定时信号做出反应是生物学中的一个基本问题。 隐花色素(Crys)是进化上保守的蓝光受体或核心生物钟 在从细菌到人类的所有主要进化谱系中都发现了这种成分。我们的长期目标 是了解隐花色素信号转导的分子机制和 调控，以拟南芥CRY2为模型系统。拟南芥CRY2是目前最好的- 研究了植物隐花色素。我的实验室已经发现了这种功能的大多数已知方面 CRY2的信号转导机制。在上一个资金周期中，我们发现 CRY2的光激活及其调控机制。我们发现光激发的CRY2 经历均二聚变得活跃；光激活的CRY2被Blue- 隐色素的光抑制剂(BIC1和BIC2)。光激活的CRY2也被磷酸化 至少24个丝氨酸和苏氨酸残基上的四个光调节蛋白激酶(ppk1-4)。 磷酸化的CRY2不仅具有完全的活性，而且还经历泛素化和降解。 然而，CRY2信号转导的几个重要问题仍然没有解决，包括如何 Cry2介导基因转录和转录后变化的光调控 表达调控植物发育，以及CRY2本身是如何受光调控的 植物的光敏性。此续订申请尝试基于以下方面解决这些问题 我们最近的实验结果。

Summary How cells respond to light and/or timing signal is a fundamental question in biology. Cryptochromes (CRYs) are evolutionarily conserved blue light receptors or the core circadian clock components found in all major evolutionary lineages, from bacteria to human. Our long-term goal is to understand the molecular mechanisms underlying cryptochrome signal transduction and regulation, using Arabidopsis CRY2 as a model system. Arabidopsis CRY2 is presently the best- studied plant cryptochrome. My laboratory has discovered most known aspects of the function and signal transduction mechanisms of CRY2. In the previous funding cycle, we discovered the photoactivation and regulatory mechanisms of CRY2. We found that photoexcited CRY2 undergoes homodimerization to become active; photoactivated CRY2 is inactivated by the Blue- light Inhibitors of Cryptochrome (BIC1 and BIC2). Photoactivated CRY2 is also phosphorylated by four Photoregulatory Protein Kinases (PPK1-4) on at least 24 serine and threonine residues. Phosphorylated CRY2 is not only fully active but also undergoes ubiquitination and degradation. However, several important questions of CRY2 signal transduction remain unsolved, including how CRY2 mediate light regulation of transcriptional and post-transcriptional changes of gene expression to modulate plant development and how CRY2 itself is regulated by light to modulate photosensitivity of plants. This renewal application attempt to address those questions based on results of our recent experiments.