Molecular mechanisms of auxin response in Arabidopsis

拟南芥生长素反应的分子机制

• 批准号: 6693316
• 负责人: WILLIAM M GRAY
• 金额: $ 22.49万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6693316
• 关键词: Arabidopsis; SDS polyacrylamide gel electrophoresis; biological signal transduction; gene expression; hormone regulation /control mechanism; immunoprecipitation; indoleacetate; mass spectrometry; mitogen activated protein kinase; molecular genetics; phosphorylation; plant extracts; plant genetics; plant growth /development; plant growth regulators; plant physiology; protein protein interaction; ubiquitin; western blottings; yeast two hybrid system

DESCRIPTION (provided by applicant): The hormone auxin regulates virtually every aspect of plant growth and development. Genetic and molecular studies with Arabidopsis have defined the SCFTIR1 ubiquitin-ligase complex as a positive regulator of auxin response. Recent findings indicate that auxin promotes SCFTIR1-mediated ubiquitination of the Aux/IAA proteins, a large family of transcriptional regulators which negatively regulate auxin response. The subsequent proteasome-mediated degradation of the Aux/IAAs derepresses the auxin response pathway resulting in changes in growth and development. We have shown that Aux/IAA proteins physically interact with the SCFTIR1 complex in crude seedling extracts. Auxin promotes Aux/IAA degradation by targeting these factors to the SCFTIR1 ubiquitin-ligase by an undetermined mechanism. Elucidation of how auxin regulates this interaction will provide important information into the signaling events of the auxin response pathway upstream of the SCFTIR1 ubiquitin-ligase. The long-term goal of the proposed research is to understand the molecular mechanisms underlying auxin regulation of plant growth and development. The identification of the mechanisms underlying auxin action will provide new tools for modulating auxin response for agricultural and horticultural benefit. Further, since SCF-mediated ubiquitination is highly conserved, these studies will contribute toward our understanding of this mode of cellular regulation in all eukaryotes. The specific objectives of this proposal include; 1) elucidation of the nature and regulation of protein-protein interactions between the Aux/IAA transcriptional regulators and the SCFTIR1 ubiquitin-ligase complex; 2) the genetic and molecular analysis of a new class of Arabidopsis mutants defective in auxin response; 3) the molecular characterization of a mutant derivative of the AtCUL1 SCF subunit; and 4) investigate the biological significance of the interaction between the AXR2 Aux/IAA protein and the COP9 signalosome subunit CSN5.

描述(申请人提供)：激素生长素几乎调节植物生长和发育的方方面面。对拟南芥的遗传和分子研究已经将SCFTIR1泛素连接酶复合体定义为生长素反应的正调节因子。最近的发现表明，生长素促进SCFTIR1介导的AUX/IAA蛋白的泛素化，AUX/IAA蛋白是一大类转录调节因子，负向调节生长素的反应。随后蛋白酶体介导的AUX/IAA的降解降低了生长素反应途径的压力，导致生长发育的变化。我们已经证明AUX/IAA蛋白与幼苗粗提物中的SCFTIR1复合体物理上相互作用。生长素通过将这些因子靶向SCFTIR1泛素连接酶来促进AUX/IAA的降解，机制尚未确定。阐明生长素是如何调节这种相互作用的，将为了解SCFTIR1泛素连接酶上游的生长素反应途径的信号事件提供重要信息。这项研究的长期目标是了解生长素调节植物生长发育的分子机制。生长素作用机制的确定将为调节生长素对农业和园艺效益的反应提供新的工具。此外，由于SCF介导的泛素化是高度保守的，这些研究将有助于我们理解所有真核生物中的这种细胞调控模式。这一建议的具体目标包括：1)阐明AUX/IAA转录调控因子和SCFTIR1泛素连接酶复合体之间蛋白质-蛋白质相互作用的性质和调节；2)一类新的生长素反应缺陷突变体的遗传和分子分析；3)AtCUL1 SCF亚基突变体的分子特征；以及4)研究AXR2 AUX/IAA蛋白和COP9信号体亚单位CSN5相互作用的生物学意义。