AUXIN-RESISTANT MUTANTS OF ARABIDOPSIS

建议研究的长期目标是：1）了解 植物激素吲哚-3-乙酸（IAA）在植物生长中的作用， 使用拟南芥突变体的开发; 2）鉴定和表征 生长素作用所需的蛋白质。 该提案描述了 研究三种生长素抗性基因功能的实验 AXR 1、AXR 3和AXR 4。 AXR 1基因已被克隆并编码一个 与泛素激活酶（El）相似的新蛋白。 我们 我打算继续我们对这个基因的分子分析，包括 基因结构和调控的表征。 蜂窝式位置 将通过细胞分级分离研究确定Axr 1蛋白的 以及免疫荧光显微术。 Axr 1的潜在作用 将在一系列体外试验中评估泛素途径中的蛋白质。 使用纯化蛋白质的研究。 为了研究泛素化在 植物激素的作用，我们将表征泛素-蛋白质缀合物 在axr 1突变体中。 AXR 1基因的异位表达 对激素敏感性和植物发育的影响。 到 鉴定与我们分离的Axr 1蛋白相互作用的蛋白质， 一系列抑制AxR 1突变体的突变。 这些突变 （称为生长素抗性抑制子，SAR）的特性。 我们 期望这些相互作用基因的分析将提供 关于AXR 1基因功能以及SAR的重要信息 的位点 我们还建议研究另外两个生长素抗性基因， AXR 3和AXR 4。 axr 3和axr 4突变体的表型表明， 基因编码激素作用所需的蛋白质。 我们打算克隆 并描述这两个位点的特征。 我们预计，我们的研究将导致重要的新见解， 植物激素作用的机理。 此外，我们对 AXR 1基因可能有助于理解细胞凋亡的调控机制。 所有的真核生物。 泛素途径与多种 细胞过程，包括细胞周期控制，DNA复制，基因 表达、病毒感染和肿瘤发生。 我们的研究表明， 类E1蛋白的变化导致植物激素的减少， 灵敏度 因此，对这种蛋白质的进一步分析可能会导致 发现了一种新的泛素调节功能。

The long-term goals of the proposed research are: 1) to understand the role of the plant hormone indole-3-acetic acid (IAA) in plant growth and development using mutants of Arabidopsis; 2) to identify and characterize the proteins required for auxin action. This proposal describes experiments which address the function of three auxin-resistance genes called AXR1, AXR3,and AXR4. The AXR1 gene has been cloned and encodes a novel protein with similarity to ubiquitin-activating enzyme (El). We intend to continue our molecular analysis of this gene, including the characterization of gene structure and regulation. The cellular location of the Axr1 protein will be established by cell fractionation studies as well as immunofluorescence microscopy. The potential role of the Axr1 protein in the ubiquitin pathway will be assessed in a series of in vitro studies using purified protein. To examine the role of ubiquitination in plant hormone action, we will characterize ubiquitin-protein conjugates in the axr1 mutants. The effects of ectopic expression of the AXR1 gene on hormone sensitivity and plant development will be determined. To identify proteins which interact with the Axr1 protein we have isolated a series of mutations which suppress the axr1 mutants. These mutations (called suppressor of auxin resistance, sar) will be characterized. We expect that the analysis of these interacting genes will provided important information on the function of the AXR1 gene as well as the SAR loci. We also propose to study two additional auxin-resistance genes called AXR3 and AXR4. The phenotypes of axr3 and axr4 mutants suggest that both genes encode proteins required for hormone action. We intend to clone and characterize both of these loci. We anticipate that our studies will lead to significant new insight into the mechanism of plant hormone action. In addition, our analyses of the AXR1 gene may contribute to an understanding of regulatory mechanisms in all eukaryotes. The ubiquitin pathway has been implicated in diverse cellular processes, including cell cycle control, DNA replication, gene expression, viral infection and oncogenesis. Our studies indicate that changes in an E1-like protein result in a reduction in plant hormone sensitivity. Thus, further analysis of this protein may lead to the discovery of a new regulatory function for ubiquitin.