PHYTOCHROME--BIOGENESIS AND MOLECULAR PROPERTIES

光敏色素是一种控制基因表达的调控主开关 以回应来自环境的战斗信号。的长期目标是 这项拟议的研究旨在定义这一现象的分子机制 实施了监管。这项建议的具体目标是：(A) 鉴定光敏色素A的序列和结构特征 负责其调节作用的分子；和(B)定义 拟南芥PhyA基因多结构域启动子中的调控元件 负责从多个转录起点进行差异表达 网站。 实验方法将包括：(A)生化分析以 评估燕麦光敏色素A具有蛋白激酶的可能性 与原核感受器蛋白相似的活性；(B)过表达 转基因拟南芥和转基因燕麦光敏色素A的诱变 微生物鉴定在结构和功能上的重要性 结构域和残基；(C)诱变光敏色素A的显微注射 转入光敏色素缺陷型转基因拟南芥细胞 光敏色素反应启动子-报告基因融合构建用于鉴定 瞬变光感受器中的功能关键序列 表达鉴定；(D)生产均一的光敏色素A 在微生物中过表达制备X射线制剂 晶体分析；和(E)缺失和序列替换 拟南芥PhyA启动子在转基因拟南芥中的分析 描绘了参与这一调控的顺式作用DNA序列 复合促进剂。 这项研究的意义在于，它将有助于界定 中央调控分子控制基因的机制 表情。因为光敏色素似乎还没有分子 在其他真核生物中，对这一机制的阐明具有 有可能扩大我们对以下战略的理解 真核细胞调控基因表达对环境的响应 刺激物。

Phytochrome is a regulatory master switch that controls gene expression in response to fight signals from the environment. The long term goal of the proposed research is to define the molecular mechanism by which this regulation is exerted. The specific objectives of this proposal are: (a) to identify sequence and structural features of the phytochrome A molecule responsible for its regulatory action; and (b) to define regulatory elements in the multidomain phyA gene promoter Arabidopsis responsible for differential expression from multiple transcription start sites. The experimental approaches will include: (a) biochemical analysis to assess the possibility that Avena phytochrome A has protein kinase activity similar to prokaryotic sensor proteins; (b) overexpression of mutagenized Avena phytochrome A in transgenic Arabidopsis and microorganisms to identify structurally and functionally important domains and residues; (c) microinjection of mutagenized phytochrome A into phytochrome-deficient transgenic Arabidopsis cells carrying phytochrome-responsive promoter-reporter fusion constructs to identify functionally critical sequences in the photoreceptor by transient expression assay; (d) production of homogeneous phytochrome A preparations by overexpression in microorganisms for X-ray crystallographic analysis; and (e) deletion and sequence substitution analysis of the Arabidopsis phyA promoter in transgenic Arabidopsis to delineate cis-acting DNA sequences involved in the regulation of this complex promoter. The significance of this research is that it will help define the mechanism by which a central regulatory molecule controls gene expression. Because phytochrome appears as yet to have no molecular counterpart in other eukaryotes, elucidation of this mechanism has the potential to broaden our understanding of the strategies used by eukaryotic cells to regulate gene expression in response to environmental stimuli.