Histone Eviction and Mediator Function in Transcriptional Activation in Yeast

智力优势：这个项目的长期目标是对真核生物的转录控制机制有新的理解。基因转录调控是所有细胞生长、发育和对环境反应的中心，因此，了解转录调控是遗传学的中心目标。这个项目的具体目标是对基因激活过程中染色质重塑以及中介复合体在基因调控中的作用有新的认识。在包括人类在内的高等生物体中，DNA通过包裹组蛋白的八聚体被包装成核小体。这对将DNA转录成RNA所需的蛋白质-DNA相互作用造成了潜在的障碍，因此在许多基因上，这些核小体必须被改造才能进行转录。这个项目将集中在酿酒酵母CHA1基因的染色质重塑上。遗传和生化方法将被用来研究重塑导致组蛋白在CHA1和其他可诱导启动子上被驱逐的机制。还将进行研究，以调查介体复合体在酵母转录调控中的作用。介体是一个大的、多亚基的复合体，由尾部、中间和头部模块组成，这些模块连接了激活子和一般的转录机制。介体在真核生物中高度保守，是许多调控信号的通道，但其控制基因表达的机制尚不清楚。将进行研究，以确定中介复合体的一个特定部分，称为Tail模块，是否除了招募中间模块和头部模块的要求外，还具有特定的功能，并确定Mediator的Tail模块在CHA1激活、整个基因组招募Mediator和转录抑制中的作用。总体而言，该项目将提供有关转录激活的基本方面的新信息，目前对此知之甚少。转录机制在真核生物中是非常保守的。因此，从这项工作中获得的信息将得到广泛的应用。广泛的影响这项研究将包括培养研究生和博士后研究员。此外，将招募本科生作为暑期实习生参与该项目，由REU补助金提供资金。该项目还将产生来自微阵列研究的大型数据集，这些数据集将通过向公共储存库(GEO)提供原始数据文件和通过从主要研究人员的网站下载更方便用户的经处理的数据文件而向公众提供。

Intellectual merit: The long term goal of this project is to gain new understanding into mechanisms of transcriptional control in eukaryotes. Regulation of gene transcription is central to growth, development, and response to environment in all cells; thus, understanding transcriptional control is a central goal in genetics. The specific goals of this project are to gain new insight into chromatin remodeling during gene activation, and into the role of the Mediator complex in gene regulation. DNA in higher organisms, including humans, is packaged into nucleosomes by wrapping around an octamer of histone proteins. This creates a potential impediment to protein-DNA interactions needed for transcription of DNA into RNA, and so at many genes these nucleosomes must be remodeled to allow transcription to occur. This project will focus on chromatin remodeling at the CHA1 gene in the yeast Saccharomyces cerevisiae. Genetic and biochemical approaches will be used to examine the mechanism by which remodeling leads to histone eviction at CHA1 and at additional inducible promoters. Studies will also be conducted to investigate the role of the Mediator complex in transcriptional regulation in yeast. Mediator is a large, multi-subunit complex, comprising tail, middle, and head modules that bridges activators, whose binding is the initial step in gene activation, and the general transcription machinery. Mediator is highly conserved across the eukaryotic kingdom, and serves as a conduit for many regulatory signals, but the mechanism by which it controls gene expression is not well understood. Research will be carried out to determine whether one specific part of the Mediator complex, called the tail module, has specific functions aside from its requirement for recruitment of the middle and head modules, and to determine the role of the tail module of Mediator in CHA1 activation, in genome-wide recruitment of Mediator, and in transcriptional repression. Overall, this project will provide new information on fundamental aspects of transcriptional activation which at present is poorly understood. Transcriptional mechanisms are well conserved across eukaryotes. Hence, the information gained from this work will be broadly applicable.Broader impactThis research will include training of a graduate student and postdoctoral fellow. In addition, undergraduates will be recruited to participate in this project as summer interns, to be funded by REU supplements. The project will also result in generation of large data sets from microarray studies, and these will be made publicly available, both by providing raw data files to a public repository (GEO), and by making more user-friendly, processed data files available for download from the principal investigator's web site.