Plant photoreceptor CRY2 and Signaling Mechanism

描述（由申请人提供）：生物体如何对光作出反应以及光敏感受器如何介导光反应是生物学中的基本问题。我们的长期目标是找到这些问题的分子解释，使用隐花色素感光器作为模型系统。隐色素（CRY）是在包括人类在内的所有进化谱系中发现的蓝色/UV-A光受体和/或昼夜节律振荡器的核心成分。我的实验室主要研究植物隐色素。在之前的资助期内，我们发现了两种主要的CRY2信号转导机制：基于CIB1 （Cryptochrome-Interacting bHLH 1）的转录调控机制和基于SPA1/COP1 （Suppressor of Phytochrome A1/ Constitutive phoorphphogenesis 1）的蛋白水解调控机制。最近，我们发现了一个与CIB1相互作用的蛋白FOF1（开花1的F-box），负责蓝光调节的CIB1降解；两种新的蓝光特异性CRY2相互作用蛋白：PRR5（伪反应调节因子5）是生物钟的核心蛋白，BIC1 （CRYs 1的蓝光抑制剂）抑制蓝光依赖性的磷酸化、降解和CRY1和CRY2的活性。基于这些发现和新开发的工具，我们建议研究光信号转导的三个关键问题：CRY光感受器光激发的光化学机制，CRY复合物的功能和调控机制，以及一种新的编码序列（CDS）依赖性蓝光调控CRY2表达的机制。

DESCRIPTION (provided by applicant): How organisms respond to light and how photosensory receptors mediate light responses are basic questions in biology. Our long-term goal is to find the molecular explanation of these questions, using the cryptochrome photoreceptor as a model system. Cryptochromes (CRY) are the blue/UV-A light receptors and/or core components of the circadian oscillator found in all evolutionary lineages including human. My laboratory focuses on the study of plant cryptochromes. In the previous funding periods, we discovered two major CRY2 signal transduction mechanisms: the CIB1 (Cryptochrome-Interacting bHLH 1)-based transcription- regulatory mechanism and SPA1/COP1 (Suppressor of Phytochrome A 1/Constitutive Photomorphogenesis 1)-based proteolysis-regulatory mechanism. More recently, we identified a CIB-interacting protein FOF1 (F-box of Flowering 1) responsible for the blue light-regulated degradation of CIB1; two new blue light-specific CRY2-interacting proteins: PRR5 (Pseudo Response Regulator 5) that is a core protein of the circadian clock, and a novel protein BIC1 (Blue- light Inhibitor of CRYs 1) tha suppresses blue light-dependent phosphorylation, degradation, and activities of CRY1 and CRY2. Based on these discoveries and newly developed tools, we propose to study three key issues of light signal transduction: the photochemical mechanism underlying photoexcitation of the CRY photoreceptor, mechanisms governing the function and regulation of the CRY complexome, and the mechanism underlying a novel coding sequence (CDS)-dependent blue light regulation of CRY2 expression.