ELUCIDATION OF A HORMONAL RESPONSE PATHWAY

植物激素的作用机制还不完全清楚。一个 转导途径的一部分涉及改变水平的机制 生理反应所需的基因产物。这个 这种激素诱导的基因表达的调节在一定程度上是受控制的。 在转录水平上。这项提案将重点放在 结合核蛋白的编码基因的特征 植物启动子在植物中具有重要作用的区域 植物激素脱落酸(ABA)对基因表达的调节。我们 我分离了两个基因的cdna克隆，它们的蛋白质结合到不同的 小麦ABA调控启动子(Em)的功能区。一位AT富豪 Em启动子的区域似乎刺激了在 一种激素不依赖的方式。识别这一点的结合蛋白 区域具有植物高迁移率基团(HMG)核的特性 蛋白。Em启动子的另一个区域包含ABA反应 元素，并与另一种具有以下序列的蛋白质结合 具有亮氨酸拉链基序的转录调节蛋白。 实验的目的是：确定每个基因的特征并分离出其他基因 他们的家庭成员；遵循每个基因在不同的 组织中ABA水平和Em的表达；定义 蛋白质/DNA相互作用的特定结合区；并测试 蛋白质的功能与它们在细胞内的可能作用有关 利用植物和酵母体内检测系统研究ABA反应途径。全 这些方法中的任何一种都应该导致中间体的识别 在ABA反应链中，并有助于阐明ABA反应 途径类似于激素对其他植物基因表达的调节 真核生物。

The mechanism of action of phytohormones is not completely understood. A part of the transduction pathway involves mechanisms that alter the levels of gene products that are required for the physiological response. The regulation of this hormone-induced gene expression is in part controlled at the level of transcription. This proposal will focus on the characterization of the genes coding for nuclear proteins that bind to regions of plant promoters that are functionally important in the regulation of gene expression by the phytohormone abscisic acid (ABA). We have isolated cDNA clones of two genes whose proteins bind to different functional regions of an ABA-regulated promoter (Em) from wheat. An AT-rich region of the Em promoter appears to stimulate the level of expression in a hormone-independent manner. The binding protein that recognizes this region has the properties of a plant high mobility group (HMG) nuclear protein. A different region of the Em promoter contains an ABA response element and binds a different protein which has the sequence of a transcriptional regulatory protein possessing a leucine zipper motif. Experiments are proposed to: characterize each gene and isolate other members of their families; follow the expression of each gene in different tissues with respect to the levels of ABA and expression of Em; define the specific binding regions of the protein/DNA interaction; and, test the functionality of the proteins with respect to their possible roles in the ABA response pathway by using plant and yeast in vivo assay systems. All of these approaches should result in the identification of intermediates in the ABA response chain and help elucidate whether this ABA response pathway is analogous to hormonal regulation of gene expression in other eukaryotes.