Genetic Biochemical Studies of Plant Steroid Signaling

描述（由申请人提供）：动物和植物都使用类固醇作为 用于生理和发育调节的信号分子（激素）。 在植物中，油菜素类固醇（BR）具有生长促进活性， 对正常生长和发育至关重要。BR生物合成缺陷 和反应能力会引起巨大的发育变化， 由于细胞伸长和扩展减少而引起的侏儒症，雄性不育，延迟 生殖发育和光生长形态的发展， 黑了BR由细胞表面受体激酶BAII感知。BR如何 信号从质膜上的BRI 1转导到其它细胞， 核反应仍然未知。该建议旨在获得分子 了解模式植物拟南芥中的BR信号通路 利用分子遗传学、生物化学和细胞生物学的方法， 生物学首先，我们已经发现BRI 1受体激酶在一个大的 蛋白复合物，我们假设其他与BRI 1相关的蛋白质， 受体复合物是受体功能所必需的。我们计划 使用亲和纯化鉴定与BRI 1相关的蛋白质， 使用反向遗传和 分子方法第二，我们已经分离并进行了初步的 一种新的BR信号转导突变体bzr 1 -1 D及其相应基因BZR 1的研究 基于这些研究，我们假设BZR 1作为一种积极的 BRI 1下游BR反应途径中的调节子。我们计划进一步 通过鉴定bzrl的功能丧失等位基因来表征BZRl基因， bzr 2基因，通过分析BZR 1与BR信号转导相关基因的相互作用， 途径，并通过确定BZR 1蛋白的生化活性。我们 还计划鉴定和表征BZR 1相互作用蛋白， 基因内和基因外突变的遗传学研究， bzr 1 - 1D突变体表型。最后，我们筛选并分离出 与BR信号传导相关的其他突变体。我们已经克隆了 对应于这些突变体之一，BZR 6，其编码一种小蛋白。我们 假设BZR 6可能作为拮抗BR肽配体起作用 信令或作为用于BR响应的辅助信号之一。我们计划 确定BZR 6及其同源物BZL 1的功能。

DESCRIPTION (provided by applicant): Both animals and plants use steroids as signaling molecules (hormones) for physiological and developmental regulation. In plants, brassinosteroids (BRs) have growth-promoting activity and are essential for normal growth and development. Deficiencies in BR biosynthesis and responsiveness cause dramatic developmental alterations that include dwarfism due to reduced cell elongation and expansion, male sterility, delayed reproductive development, and development of light-grown morphology in the dark. BRs are perceived by the cell surface receptor kinase BAIl. How the BR signal is transduced from BRI1 on the plasma membrane to other cellular and nuclear responses remains unknown. This proposal aims at obtaining a molecular understanding of the BR signaling pathways in the model plant Arabidopsis thaliana, using approaches of molecular genetics, biochemistry, and cell biology. First, we have found that the BRI1 receptor kinase is in a large protein complex, and we hypothesize that other proteins associated with BRI1 in the receptor complex are required for the receptor function. We plan to identify the proteins associated with BRI1 using affinity purification and to characterize the functions of these proteins using reverse-genetic and molecular approaches. Second, we have isolated and carried out preliminary studies of a new BR-signaling mutant bzr1-1 D and the corresponding gene BZR1. Based on these studies, we hypothesize that BZR1 functions as a positive regulator in the BR response pathway downstream of BRI1. We plan to further characterize the BZR1 gene by identifying loss-of-function alleles of bzrl and bzr2, by analyzing the interaction of BZR1 with other genes of the BR signaling pathway, and by determining the biochemical activity of the BZR1 protein. We also plan to identify and characterize BZR1 interacting proteins and perform genetic studies of intragenic and extragenic mutations that suppress or enhance the bzr1 -1 D mutant phenotype. Finally, we have screened and isolated additional mutants associated with BR signaling. We have cloned the gene corresponding to one of these mutants, BZR6, which encodes a small protein. We hypothesize that BZR6 may function as a peptide ligand antagonizing BR signaling or as one of the secondary signals for the BR response. We plan to determine the functions of BZR6 and its homologue BZL1.