REGULATORY INTERACTIONS BETWEEN EUKARYOTIC PROMOTERS

酵母中转运RNA基因表达的研究进展 酿酒酵母导致了对这些RNA如何 聚合酶III转录单位的功能。 表征 核蛋白结构的野生型和突变体基因在体内高 分辨率，结合详细的生化重建已经表明， 天然染色质或重组体中活性tRNA基因的组装 模板需要单独的组装和转录的有序结合 因素 在该实验室的体内研究过程中， 发现tRNA基因启动子不仅控制了它们自己的 表达，但能够作为附近的消音器元件 RNA聚合酶II启动子。 分子间没有直接的空间干扰， 启动子参与，启动子的相对取向不 关键的是，只要tRNA基因被活跃地转录。 的 本提案中描述的实验提供了物理和遗传方面的信息 研究这类负面影响机制的方法 酵母中的转录调控。 这些研究的结果可以 对理解组织结构有着广泛的影响， 转录活性染色质，因为在较大的真核基因组中， 许多高度重复的、散布的DNA元件（例如Alu元件）具有 tRNA样启动子。

Recent studies of transfer RNA gene expression in the yeast Saccharomyces cerevisiae have led to major revisions in the picture of how these RNA polymerase III transcription units function. Characterization of the nucleoprotein structure of wild type and mutant genes in vivo at high resolution, combined with detailed biochemical reconstitution has shown that assembly of active tRNA genes in native chromatin or recombinant templates requires ordered binding of separate assembly and transcription factors. In the course of the in vivo studies in this laboratory it was found that the tRNA gene promoters not only controlled their own expression, but were capable of serving as silencer elements for nearby RNA polymerase II promoters. No direct steric interference between the promoters is involved and the relative orientation of the promoters is not critical, as long as the tRNA gene is actively transcribed. The experiments described in this proposal provide both physical and genetic approaches to investigating the mechanism of this type of negative transcriptional regulation in yeast. The results of these studies could have extensive implications for understanding the organization of transcriptionally active chromatin, since in larger eukaryotic genomes many highly repetitive, interspersed DNA elements (e.g. Alu elements) have tRNA-like promoters.