STRUCTURE AND FUNCTION OF THE LIGHT SWITCH PHYTOCHROME

光开关 PHYTOCHROME 的结构和功能

• 批准号: 2734546
• 负责人: Pill-Soon Song
• 金额: $ 13.09万
• 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 2000-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2734546
• 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光敏色素分子光开关。 红色 波长的光激活了光开关分子的Pr形式， 被吸收的红光转化为Pfr形式。 Pfr- 光敏色素然后触发两种类型的细胞信号转导， 植物，一个在转录水平上调控几个基因 在黑暗中不转录的基因和另一个涉及细胞器的基因 运动和形态/昼夜节律如发芽， 开花等，其中一些可能是由转录 调控Pfr形式（开启构象）可以恢复为 Pr形式（关闭构象）通过远红波长光，如图所示 下面 光敏色素介导光信号的分子机制 植物的反应尚未完全阐明。 长期 这项研究的目的是了解 细胞光信号转导的结构机制水平。 我们提出的研究的具体目标是了解光- 光敏色素的活化及其在分子水平上的功能作用 并以此系统为模型来探索 信号切换一般。 为了实现这些目标，我们将使用 诱变以探测发色团和荧光团之间的相互作用。 光敏色素分子的光响应域。 我们将 研究光调制的磷酸化/去磷酸化 光敏色素可能是光信号转导的起始事件 级联。 最后，我们将建立一种光敏色素的体外检测方法 活性的基础上可能参与G蛋白在 植物光敏色素介导的信号转导，类似于 视觉兴奋过程与激素/受体调节的基因表达 在动物身上。