PHOTOREGULATORY SIGNAL TRANSDUCTION

对蓝光的反应能力在整个人类中广泛存在。 生物王国其中许多反应，包括一些发现， 细菌、真菌、昆虫和植物，被认为是由 黄素蛋白尽管事实上蓝光反应是第一个 达尔文在100多年前描述的光感受器，迄今为止还没有这样的光感受器 被描述。 这一建议是基于最近的分离和表征， 拟南芥的HY 4基因。突变植物有缺陷， 该基因显示出对蓝光的选择性不敏感性。的序列 HY 4基因显示出与微生物光解酶惊人的相似性。 这些酶是一类罕见的黄素蛋白，可以修复紫外线损伤的DNA 并且通过吸收蓝光或UV光而被激活;也就是说; 它们起到光感受器的作用。这种表型的组合 hy 4突变体的特性及其与光解酶的序列相似性 是HY 4编码黄素基蓝光的有力证据 光感受器 这个建议是生物化学、分子学和遗传学的结合 进一步表征HY 4光感受器的方法。 涉及电生理学和生物物理学的合作研究 方法也包括在内。HY 4将从转基因烟草中纯化 植物，以及拟南芥，并尝试将其过表达 它在酵母和杆状病毒感染的异源表达系统中 昆虫细胞纯化的蛋白质将用于旨在 确定其生物化学特性，包括 发色团 根据光解酶的性质，人们认为， HY 4将起到氧化还原剂的作用。HY 4介导蓝色的能力 离体等离子体氧化还原性质的光依赖性变化 膜将被检查，分子和遗传方法将 用于搜索光调节信号中的附加成分 转导途径 感知和响应光的能力在整个世界都是普遍的。 生物界和信号机制的性质， 与这些反应相关的是广泛的兴趣。同样重要的是， 特别是在人类嗜中性粒细胞和吞噬作用的研究中， 氧化还原反应影响细胞活性的手段 膜。拟议的研究充分利用了 拟南芥的分子和遗传分析，将提供一个 对我们理解这些重要的 流程.

The ability to respond to blue light is widespread throughout the biological kingdom. Many of these responses, including some found in bacteria, fungi, insects and plants, are believed to be mediated by flavoproteins. In spite of the fact that blue light responses were first described by Darwin over 100 years ago, no such photoreceptor has hitherto been described. This proposal is based on the recent isolation and characterization of the HY4 gene of Arabidopsis thaiiana. Mutant plants that are defective for this gene show a selective insensitivity to blue light. The sequence of the HY4 gene shows a striking similarity to that of microbial photolyases. These enzymes are a rare class of flavoproteins that repair UV-damaged DNA and are activated by the absorption of either blue or UV light; that is; they function as photoreceptors. This combination of the phenotypic characteristics of hy4 mutants and the sequence similarity to photolyases is compelling evidence that HY4 encodes a flavin-based blue light photoreceptor. This proposal is a combination of biochemical, molecular, and genetic approaches to the further characterization of the HY4 photoreceptor. Collaborative studies involving electrophysiological and biophysical approaches are also included. HY4 will be purified from transgenic tobacco plants, as well as Arabidopsis, and attempts will be made to overexpress it in heterologous expression systems in yeast and baculovirus infected insect cells. The purified protein will be used in studies aimed at determining its biochemical characteristics including the nature of the chromophores. Based on the properties of photolyases, it is believed that HY4 will function as a redox agent. The ability of HY4 to mediate blue light-dependent changes in the redox properties of isolated plasma membranes will be examined and both molecular and genetic approaches will be used to search for additional components in the photoregulatory signal transduction pathway. The ability to perceive and respond to light is universal throughout the biological kingdom and the nature of the signaling mechanisms that are associated with these responses is of wide interest. Equally important, especially in the study of human neutrophils and phagocytosis, is the means by which redox reactions impact on the activity of cellular membranes. The proposed studies, taking full advantage of the merits of both molecular and genetic analysis in Arabidopsis, will provide a significant contribution to our understanding of these important processes.