YEAST RDNA PROJECT

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。为了研究染色质蛋白在基因表达和沉默中的作用，我们分析了芽殖酵母核糖体DNA（rDNA）位点的染色质蛋白。核糖体是蛋白质合成的基本过程所必需的，其表达根据细胞需要多少蛋白质来调节。这反过来又取决于他们分裂的力度。在指数增长的野生型酵母中，在任何时候只有大约一半的~150个串联重复的rDNA基因是活跃的，但是随着生长平台期，所有的重复序列都变得沉默。由于重复序列具有相同的序列，它们之间的行为差异必然是由相关因素的差异引起的。该项目有三个具体目标。首先，我们将从酵母细胞中纯化天然rDNA染色质。其次，我们将鉴定结合的蛋白质，绘制它们沿rDNA沿着的位置，并使用质谱法确定它们是如何被修饰的。第三，我们将确定染色质组成和rDNA之间的修饰差异，这是？上？（转录）和rDNA是什么？关闭？（沉默），并描述它们的分布如何随着基因座逐渐激活或沉默而变化。最终的目标不仅是一个活跃的和沉默的rDNA染色质（包括组蛋白修饰）的地图，但也rDNA激活和沉默的动态模型。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In order to study the role of chromatin proteins in gene expression and silencing, we are analyzing chromatin proteins at the ribosomal DNA (rDNA) locus in budding yeast. Ribosomes are required for the fundamental process of protein synthesis, and their expression is regulated according to how much proteins cells need. This in turn depends on how aggressively they are dividing. In wild type yeast growing exponentially, only about half the ~150 tandemly repeated rDNA genes are active at any time, but as growth plateaus all of the repeats become silenced. Since the repeats have the same sequence, differences in behavior between them must be caused by differences in associated factors. This project has three specific aims. First we will purify native rDNA chromatin from yeast cells. Second we will identify the bound proteins, map their locations along the rDNA, and determine how they are modified using mass spectrometry. Third we will determine differences in chromatin composition and modifications between rDNA that is ?on? (transcribed) and rDNA that is ?off? (silent), and describe how their distributions change as the locus is progressively activated or silenced. The ultimate goal is not only a map of active and silenced rDNA chromatin (including histone modifications), but also a dynamic model of rDNA activation and silencing.