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.

植物拥有高度敏感的分子光开关光敏色素。 红色的 波长的光激活光开关分子的 Pr 形式， 被吸收的红光转化为Pfr形式。 Pfr- 然后光敏色素触发两种类型的细胞信号转导 植物，一种在转录水平调控多个基因的植物 不在黑暗中转录的和另一个涉及细胞器的 运动和形态/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（开启构象）可以恢复为 远红波长光形成Pr形式（关闭构象），如图 以下。 光敏色素介导的光信号的分子机制 植物的反应尚未完全阐明。 长期来看 拟议研究的目的是了解 结构机械水平的细胞光信号转导。 我们所提出的研究的具体目标是了解光 光敏色素的激活及其在分子水平上的功能作用 并以此系统为模型来探索其分子机制 一般信号切换。 为了实现这些目标，我们将使用站点定向 诱变以探测发色团和发色团之间的相互作用 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 光敏色素作为光信号转导中可能的初始事件 级联。 最后，我们将开发光敏色素的体外测定方法 基于 G 蛋白可能参与的活性 植物中光敏色素介导的信号转导，类似于 视觉兴奋过程和激素/受体调节的基因表达 在动物中。