Histone Eviction and Mediator Function in Transcriptional Activation in Yeast

学术价值：本项目的长期目标是对真核生物转录控制机制有新的认识。 基因转录的调控是所有细胞生长、发育和对环境反应的核心;因此，理解转录调控是遗传学的核心目标。该项目的具体目标是获得新的见解染色质重塑基因激活过程中，并进入基因调控的中介复合体的作用。包括人类在内的高等生物的DNA通过包裹组蛋白八聚体而包装成核小体。 这对DNA转录成RNA所需的蛋白质-DNA相互作用产生了潜在的障碍，因此在许多基因中，这些核小体必须被重塑以允许转录发生。 本项目将重点研究酿酒酵母中CHA 1基因的染色质重塑。 遗传和生物化学的方法将被用来检查机制，重塑导致组蛋白驱逐在CHA 1和其他诱导型启动子。还将进行研究以调查介体复合物在酵母转录调节中的作用。 介体是一个大的多亚基复合物，包括尾部、中部和头部模块，其桥接激活剂和一般转录机制，激活剂的结合是基因激活的初始步骤。 介体在真核生物界是高度保守的，并作为许多调节信号的管道，但它控制基因表达的机制还不清楚。 研究将进行，以确定是否一个特定的部分，调解人复合物，称为尾部模块，具有特定的功能，除了其要求招聘的中间和头部模块，并确定的作用，尾部模块的调解人在CHA 1激活，在基因组范围内招聘调解人，并在转录抑制。 总的来说，这个项目将提供新的信息，转录激活的基本方面，目前是知之甚少。 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具有广泛的适用性。更广泛的影响这项研究将包括对研究生和博士后研究员的培训。 此外，大学生将被招募参加这个项目作为暑期实习生，由REU补充资助。该项目还将导致从微阵列研究中产生大量数据集，这些数据集将通过向公共存储库（GEO）提供原始数据文件和提供更方便用户的处理后的数据文件供主要研究者网站下载而公开。

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.