Role of Plant Transcriptional Adaptors in Cold-Regulated Gene Expression

9728462托马斯有多少植物提高了对低温的耐寒性，这种现象被称为冷驯化。最近的证据表明，冷适应涉及冷调节基因的诱导。一个主要的研究目标是确定植物如何感知低温并处理“冷信号”来诱导耐寒基因的表达。为此，我们已经分离到一个拟南芥的cDNA，它编码一个转录激活子，与CRT/DRE序列结合，CRT/DRE序列是一个冷和干旱响应的DNA调控元件。这项提议的重点是确定该因子Cbf I是如何激活转录的。将采取的方法基于两个重要的观察结果：1)CBF1在酵母中的转录活性需要至少三个转录适配蛋白的作用，即ADA2、ADA3和GCN5；以及2)拟南芥编码酵母ADA2蛋白的同源物。因此，植物可能有一个与酵母的ADA复合体相关的转录适配系统，该系统可能参与了低温和干旱调控的基因表达。这些假说将通过以下几个方面得到验证：1)确定CBF1激活域的边界和关键残基；2)确定CBF1激活域是否与拟南芥ADA2蛋白直接相互作用，如果是，则确定相互作用是否受温度或脱水胁迫的影响；3)确定拟南芥ADA2蛋白是否与ADA3和GCN5蛋白的同源物或与新的植物适配器蛋白相互作用；以及4)评估拟南芥ADA2蛋白参与植物生长发育和对各种环境胁迫的反应。该项目的结果将提供有关植物转录激活剂与之相互作用以刺激转录的蛋白质性质的基本新信息，这是一个在植物中几乎一无所知的区域。此外，它们将提供有关冷调控基因表达的重要新信息，并将为更全面地理解植物基因调控打开大门。植物通过合成特定的蛋白质来应对冷胁迫。这种调节反应是由转录水平的基因表达变化引起的，转录水平是DNA复制到RNA的过程。这些转录变化是由称为转录因子的蛋白质和DNA之间的相互作用引起的。这个项目将研究在冷应激过程中与转录因子相互作用的蛋白质，称为转录适配因子。在酵母中已经发现了类似的蛋白质，但这是第一次表明它们存在于植物中。该项目将确定这些蛋白质是否在植物中发挥类似的作用，并定义转录适配分子中与冷激活转录因子相互作用至关重要的部分。这一理解可能有助于我们理解植物如何适应寒冷。

9728462 Thomashow Many plants increase in freezing tolerance in response to low nonfreezing temperatures, a phenomenon known as cold acclimation. Recent evidence indicates that cold acclimation involves the induction of cold-regulated genes. A primary research objective is to determine how plants sense low temperature and process the "cold signal" to induce the expression of freezing tolerance genes. Toward this end, an Arabidopsis cDNA has been isolated that encodes a transcriptional activator that binds to the CRT/DRE sequence, a cold- and drought-responsive DNA regulatory element. The focus of this proposal is to determine how this factor, CBF I, activates transcription. The approach that will be taken is based on two important observations: 1)the transcriptional activity of CBF1 in yeast requires the action of at least three transcriptional adaptor proteins, ADA2, ADA3, and GCN5; and 2) Arabidopsis encodes a homolog of the yeast ADA2 protein. Thus, plants may have a transcriptional adaptor system related to the ADA complex of yeast and this system may be involved in cold- and drought-regulated gene expression. These hypotheses will be tested by: 1) defining the boundaries and key residues of the CBF1 activation domain; 2) determining whether the CBF1 activation domain interacts directly with the Arabidopsis ADA2 protein and if so, whether the interaction is affected by temperature or dehydration stress; 3) determining whether the Arabidopsis ADA2 protein interacts with homologs of the ADA3 and GCN5 proteins or with novel plant adaptor proteins; and 4) assessing the extent to which the Arabidopsis ADA2 protein is involved in plant growth and development and response to various environmental stresses. The results of this project will provide fundamental new information on the nature of the proteins with which plant transcriptional activators interact to stimulate transcription, an area about which virtually nothing is known in plants. In addition, they will provide significant new informat ion about cold-regulated gene expression and will open the door to a more globally integrated understanding of plant gene regulation. Plants respond to cold stress by synthesizing specific proteins. This regulatory response is caused by changes in gene expression at the level of transcription, the process by which DNA is copied into RNA. These transcriptional changes are caused by interactions between proteins, called transcription factors, and DNA. This project will study proteins that interact with transcription factors, called transcriptional adaptors, during cold stress. Analogous proteins have been discovered in yeast, but this is the first indication that they exist in plants. This project will determine whether these proteins play a similiar role in plants and define the parts of the transcriptional adaptor molecule that are critical for interacting with the cold-activated transcription factor. This understanding may contribute to our understanding of how plants adapt to cold.