Transcriptional Silencing Near tRNA Genes

描述（来自申请人摘要的逐字记录）：几种不同类型 真核细胞核中DNA元件的变化引起基因的区域负调控 转录，称为“沉默”。“在最好的研究例子， 沉默发生在端粒附近， 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。这个实验室以前注意到第三种形式的 酵母中的沉默RNA聚合酶II的转录被拮抗， tRNA基因的上游和下游。这种抑制作用称为“tRNA 基因介导（tgm）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位阻引起的 约束力tgm沉默的程度及其发生的条件 是可变的，取决于pol II启动子。这种民意调查的能力 启动子选择性地克服沉默效应表明， 沉默从根本上不同于酵母中的其他形式的沉默， 并且至少在某些情况下它起到调节作用。这些影响 可以影响大量的位点，因为大量的tRNA类 启动子分散在大多数真核生物的整个基因组中。目标 本项目的主要目的是研究条件性tgm沉默的机制。 在酵母中。

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.