Transcriptional Silencing Near tRNA Genes

描述(逐字摘自申请人的摘要)：几种不同的类型 真核细胞核中DNA元件的缺失导致基因的区域性负调控 转录，即所谓的“沉默”。在研究得最好的例子中 沉默发生在萌发过程中的端粒和沉默交配型基因座附近 酵母，酿酒酵母，但许多其他消音器的例子 在后生动物中被发现。该实验室之前注意到了第三种形式的 在酵母中沉默。RNA聚合酶II的转录被拮抗 TRNA基因的上游和下游。这种被称为“tRNA”的抑制 基因介导的沉默，“需要tRNA基因的主动转录。 并且不是由附近转录因子的直接空间封闭引起的 有约束力的。TGM沉默的程度和发生的条件 根据polII启动子的不同而不同。一些波兰人的这种能力 有选择地克服沉默效应的启动子表明，TGM 沉默与酵母中其他形式的沉默有根本的不同， 而且，它至少在某些情况下起到了监管作用。这些影响 可以影响大量的基因座，因为大量的tRNA类 启动子分布在大多数真核生物的基因组中。目标 本项目的目的是研究条件性TGM沉默的机制 放在酵母里。

DESCRIPTION (Verbatim from the applicant's abstract): Several different types of DNA elements in eukaryotic nuclei cause regional negative regulation of gene transcription, known as "silencing." Among the best studied examples of silencing occur near telomeres and silent mating type loci in the budding yeast, Saccharomyces cerevisiae, but many additional examples of silencers have been identified in metazoans. This lab previously noted a third form of silencing in yeast. Transcription by RNA polymerase II is antagonized both upstream and downstream of tRNA genes. This inhibition, termed "tRNA gene-mediated (tgm) silencing," requires active transcription of the tRNA gene and does not arise from direct steric occlusion of nearby transcription factor binding. The extent of tgm silencing and the conditions under which it occurs are variable, depending on the pol II promoter. This ability of some pol ll promoters to selectively overcome the silencing effects suggest that tgm silencing is fundamentally different from other forms of silencing in yeast, and that it serves a regulatory function in at least some cases. These effects could influence a large number of loci, since large numbers of tRNA-class promoters are dispersed in throughout the genomes of most eukaryotes. The aims of this project are to investigate the mechanism of conditional tgm silencing in yeast.