The Role of START Lipid/Sterol Binding Domains in Homeodomain Transcription Factors of Plants

START 脂质/甾醇结合域在植物同源域转录因子中的作用

• 批准号: 0517758
• 负责人: Kathrin Schrick
• 金额: --
• 依托单位: Keck Graduate Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0517758&HistoricalAwards=false
• 关键词: Role; START; Lipid; Sterol; Binding

Sterols are small water-insoluble molecules that play critical roles in growth and development of both animals and plants. Ongoing research in the field of plant molecular biology has revealed the importance of the sterol-derived brassinosteroids, which are the only steroid hormones identified from plants thus far. In addition to brassinosteroids, plants contain a wide variety of sterol compounds whose biological functions are not understood. The long-term goal of the Schrick lab is to identify and characterize the components of putative sterol signaling pathways in plants. Candidate sterol-binding proteins include a family of homeodomain (HD) transcription factors having Steroidogenic Acute Regulatory (StAR)-related lipid transfer (START) lipid/sterol-binding domains. START domains, named after the mammalian cholesterol-binding StAR protein, are found in a variety of proteins across the eukaryotes, but have been studied in only a few cases from animals. Strikingly, START domains in combination with the HD DNA-binding motif are unique to plants. This project addresses the hypothesis that the START domain found in HD transcription factors binds to lipid/sterol ligands and that this interaction controls gene expression during development. Several members of the HD-START family from Arabidopsis, maize, and rice, have crucial roles in cell differentiation and/or exhibit layer-specific expression patterns. Using the Arabidopsis thaliana Meristem Layer 1 (ATML1) and GLABRA2 (GL2) genes as models, the aim of this project will be to examine the putative role of START domains as lipid/sterol binding motifs. Potential ligands will be experimentally identified in a novel in vivo lipid/sterol-binding assay utilizing the yeast Saccharomyces cerevisiae. In the assay the START domain is expressed as part of a synthetic transcription factor that activates a reporter gene in response to ligand binding. This assay will be implemented to test a chemical library of lipid/sterol compounds for binding to candidate START domains from Arabidopsis HD-START transcription factors, and additionally will be used for mutational analysis of selected START domains. Completion of this project will provide a conceptual framework for the presumed function of plant START domains in ligand binding, potentially revealing a link between lipid/sterol metabolism and cell differentiation in plants. Moreover, this work will result in significant advances in understanding of the role of HD-START transcription factors in plant development, and will lead to important insights underlying lipid/sterol signaling mechanisms. This research will have broader impacts through multidisciplinary education of graduate students as well as undergraduates, and the information gained from this research will facilitate improvements in plant-derived substances for practical applications in biotechnology.

甾醇是一种不溶于水的小分子，在动植物的生长发育中起着至关重要的作用。植物分子生物学领域正在进行的研究揭示了甾醇衍生的油菜素类固醇的重要性，这是迄今为止从植物中发现的唯一类固醇激素。除了油菜素类固醇外，植物还含有种类繁多的类固醇化合物，其生物学功能尚不清楚。Schrick实验室的长期目标是识别和表征植物中可能的类固醇信号通路的成分。候选的固醇结合蛋白包括一个同源结构域(HD)转录因子家族，该家族具有类固醇合成急性调节(STAR)相关的脂转移(START)脂/固醇结合结构域。START结构域以哺乳动物胆固醇结合星蛋白命名，在真核生物的各种蛋白质中都有发现，但只在少数动物身上进行了研究。引人注目的是，结合HD DNA结合基序的START结构域是植物所独有的。该项目提出了一种假设，即在HD转录因子中发现的起始结构域与脂质/固醇配体结合，这种相互作用控制着发育过程中的基因表达。来自拟南芥、玉米和水稻的HD-Start家族的几个成员在细胞分化中发挥关键作用和/或表现出层特异性表达模式。以拟南芥分生组织层1(ATML1)和GLABRA2(GL2)基因为模型，本项目的目的是研究START结构域作为脂/固醇结合基序的可能作用。潜在的配体将在一种新的体内脂/固醇结合试验中被实验确定，该试验利用酿酒酵母进行。在检测中，起始结构域被表达为合成转录因子的一部分，该转录因子激活报告基因以响应配体结合。该方法将用于测试与拟南芥HD-START转录因子候选起始结构域结合的类脂/甾醇化合物化学文库，此外还将用于所选起始结构域的突变分析。该项目的完成将为植物起始结构域在配体结合中的可能功能提供一个概念性框架，潜在地揭示植物中脂/固醇代谢和细胞分化之间的联系。此外，这项工作将在理解HD-START转录因子在植物发育中的作用方面取得重大进展，并将导致对潜在的脂/固醇信号机制的重要见解。这项研究将通过对研究生和本科生的多学科教育产生更广泛的影响，从这项研究中获得的信息将有助于改进植物衍生物质在生物技术中的实际应用。