GAGA FACTOR AND HEAT SHOCK PROMOTER POTENTIATION

黑腹果蝇的热休克反应的特点是主要热休克基因的快速和强大的激活。尽管人们对热休克启动子的结构和识别启动子的转录因子了解甚多，但热休克基因转录的机制细节仍不清楚。两种转录因子，GAGA因子（GAF）和tata结合蛋白，以及RNA聚合酶II （Pol II）占据了非诱导热休克启动子。Pol II虽然能够产生小转录本，但在热休克启动子处暂停。这些因子之间的蛋白质-蛋白质和蛋白质- dna相互作用在维持启动子处的开放染色质结构和保留暂停的聚合酶中起着重要作用。为了验证这一假设，我们将构建GAF的dna结合域和相互作用域突变体，并对其进行严格的体内和体外分析。考虑到热休克启动子序列与其他启动子序列之间的相似性，以及果蝇和哺乳动物细胞中几种非热休克基因上存在暂停聚合酶，对这些GAF突变体的研究可以提供对启动子结构、聚合酶暂停和基因激活的一般理解。

The heat shock response of Drosophila melanogaster is characterized by the rapid and robust activation of the major heat shock genes. Although much is known about heat shock promoter architecture and the transcription factors which recognize the promoters, the mechanistic detail of heat shock gene transcription remain unclear. Two transcription factors, GAGA factor (GAF) and TATA-binding protein, and RNA polymerase II (Pol II) occupy the uninduced heat shock promoters. Pol II, although capable of producing small transcripts, is paused at the heat shock promoter. It is thought that the protein-protein and protein-DNA interactions among these factors play an important role in the maintenance of the open chromatin structure at the promoter and in retention of the paused polymerase. To address this hypothesis, DNA-binding domain and interaction domain mutants of GAF will be constructed and subjected to rigorous in vivo and in vitro analysis. Given the similarities between heat shock promoter sequences and those of other promoters, and the presence of a paused polymerase on several non-heat shock genes in Drosophila and in mammalian cells, studies with these GAF mutants may provide a general understanding of promoter architecture, polymerase pausing, and gene activation.