Role of Plant Transcriptional Adaptors in Cold-Regulated Gene Expression

9728462 托马斯休 许多植物对低温的反应是提高抗冻性，这种现象被称为冷驯化。最近的证据表明，冷驯化涉及冷调节基因的诱导。研究植物如何感受低温并处理低温信号以诱导抗冻基因的表达是其主要目的。为此，拟南芥cDNA已被分离，其编码与CRT/DRE序列结合的转录激活因子，CRT/DRE序列是冷和干旱响应的DNA调节元件。该提案的重点是确定该因子CBF I如何激活转录。将采取的方法基于两个重要的观察：1）CBF 1在酵母中的转录活性需要至少三种转录衔接蛋白ADA 2、ADA 3和GCN 5的作用;以及2）拟南芥编码酵母ADA 2蛋白的同源物。因此，植物可能具有与酵母的ADA复合物相关的转录衔接子系统，并且该系统可能参与冷和干旱调节的基因表达。这些假设将通过以下方式进行检验：1）确定CBF 1激活结构域的边界和关键残基; 2）确定CBF 1激活结构域是否直接与拟南芥ADA 2蛋白相互作用，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ADA 2蛋白是否与ADA 3和GCN 5蛋白的同源物或与新的植物衔接蛋白相互作用;和4）评估拟南芥属ADA 2蛋白参与植物生长和发育以及对各种环境胁迫的响应的程度。该项目的结果将提供有关植物转录激活因子相互作用以刺激转录的蛋白质性质的基本新信息，这是植物中几乎一无所知的领域。此外，它们将提供有关冷调节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，转录是DNA复制成RNA的过程。这些转录变化是由称为转录因子的蛋白质与DNA之间的相互作用引起的。该项目将研究在冷胁迫期间与转录因子相互作用的蛋白质，称为转录衔接子。在酵母中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，并确定与冷激活转录因子相互作用的转录衔接分子的部分。这种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.