STRUCTURE AND FUNCTION OF THE LIGHT SWITCH PHYTOCHROME

光开关 PHYTOCHROME 的结构和功能

• 批准号: 6018670
• 负责人: Pill-Soon Song
• 金额: $ 13.58万
• 依托单位: UNIVERSITY OF NEBRASKA LINCOLN
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6018670
• 关键词: G protein; affinity labeling; biological signal transduction; chromophore; circadian rhythms; circular dichroism; conformation; crosslink; guanosinetriphosphatase activating protein; intermolecular interaction; mass spectrometry; mutant; nonvisual photoreceptor; peptide chemical synthesis; phosphorylation; photobiology; photostimulus; phycobilin; plant proteins; protein folding; protein reconstitution; protein structure function; site directed mutagenesis

Plants possess a highly sensitive molecular light swith phytochrome. Red wavelength light activates the Pr form of the photoswitch molecule, which is converted to the Pfr form by the red light absorbed. The Pfr- phytochrome then triggers two types of cellular signal transduction in plants, one at the transcriptional level of regulation for several genes that are not transcribed in the dark and another involving organelle movement and morphological/circadian rhythms such as germination, flowering, etc, some of which may be preceded by transcriptional regulation. The Pfr form (switch-on conformation) can be reverted to the Pr form (switch-off conformation) by far-red wavelength light, as shown below. The molecular mechanism of the phytochrome-mediated photo-signal responses in plants has not been fully elucidated. The long term objective of the proposed study is to understand the mechanisms of cellular light signal transduction at the structural-mechanistic level. Our specific aim of the proposed research is to understand the light- activation of phytochrome and its functional role at the molecular level and use this system as a model to explore the molecular mechanisms of signal switching in general. For these aims, we will use site-directed mutagenesis to probe the interactions between the chromophore and the light-responsive domains of the phytochrome molecule. We will investigate the light-modulated phosphorylation/dephosphorylation of phytochrome as a possible initial event in the light signal transduction cascade. Finally, we will develop an in vitro assay of phytochrome activity based on the possible involvement of G-proteins in the phytochrome-mediated signal transduction in plants, in analogy to the visual excitation process and hormone/receptor-regulated gene expression in animals.

植物具有高度敏感的分子光化植物色素。 红色的 波长光激活Photoswitch分子的PR形式，该形式 通过吸收的红光转化为PFR形式。 PFR- 然后，植物色素触发两种类型的细胞信号转导 植物，一个在几个基因调节的转录水平上 没有在黑暗中转录，另一个涉及细胞器 运动和形态学/昼夜节律，例如发芽， 开花等，其中一些可能先于转录 规定。 PFR形式（开关构象）可以恢复为 如图所示 以下。 植物色素介导的光 - 信号的分子机制 植物的反应尚未完全阐明。 长期 拟议的研究的目的是了解 在结构机械水平上的细胞光信号转导。 我们提出的研究的具体目的是了解光 植物色素的激活及其在分子水平上的功能作用 并使用该系统作为探索分子机制的模型 信号切换一般。 对于这些目标，我们将使用网站定向 诱变以探测发色团与 植物色素分子的光反应域。 我们将 研究光调节的磷酸化/去磷酸化 植物色素作为光信号转导的可能初始事件 级联。 最后，我们将开发植物色素的体外测定 基于G蛋白可能参与的活动 植物介导的植物的信号转导，类似于 视觉激发过程和激素/受体调节的基因表达 在动物中。