Characterization of Type B Histone Acetyltransferases

描述（来自申请人摘要的逐字记录）：染色质是 使染色体DNA能够浓缩的核蛋白结构， 包装在真核细胞核中。染色质的主要蛋白质成分是 核心组蛋白（H2 A、H2 B、H3和H4）。染色质结构起着积极的 在调节许多细胞过程中的作用， 染色体DNA，如转录、DNA复制、重组和DNA 修复.由于正常细胞生长的许多方面的调节需要 严格控制这些过程，重要的是要了解它们是如何 受染色质结构的影响并与之相互作用。大部分监管 核心组蛋白的电位存在于小的，带正电荷的结构域，称为 NH 2末端的尾部。核心组蛋白NH 2-末端尾部受到一个 广泛的翻译后修饰，其中乙酰化是 最广泛的特点。组蛋白的乙酰化作用， 是细胞调节染色质结构的基本机制， 在赖氨酸残基上，使它们的正电荷消失。乙酰化状态 组蛋白由添加乙酰基的酶的相互作用控制 （组蛋白乙酰转移酶）和去除它们的酶（组蛋白 脱乙酰酶）。组蛋白乙酰基转移酶可根据其结构分为两类， 底物特异性和细胞定位。A型组蛋白 乙酰转移酶是使染色质中的组蛋白乙酰化的核酶 上下文B型组蛋白乙酰转移酶乙酰化游离组蛋白，并且可以是 在细胞质中发现。而A型组蛋白乙酰转移酶，如Gcn 5 p， 已经确定与基因表达的调节有关， B型组蛋白乙酰转移酶的功能。但使用 以酵母B型组蛋白乙酰转移酶Hat 1 p为模型，我们最近 获得的证据表明，这些酶参与沉默的染色质结构 和DNA损伤修复我们研究的主要目标是扩展这些 结果，使用分子遗传学和生物化学的组合，以定义 B型组蛋白乙酰转移酶的体内作用。这一目标将 通过三个具体目标。第一是确定机制 Hat 1 p通过该途径影响酵母附近发现的沉默染色质结构 端粒第二是表征Hat 1 p和染色质的参与 DNA双链断裂的修复。第三，我们将隔离和 表征新型B型组蛋白乙酰转移酶。

DESCRIPTION (Verbatim from the applicant's abstract): Chromatin is the nucleoprotein structure that enables chromosomal DNA to be condensed and packaged in eukaryotic nuclei. The primary protein components of chromatin are the core histones (H2A, H2B, H3, and H4). Chromatin structure plays an active role in the regulation of many cellular processes that involve accessing chromosomal DNA, such as transcription, DNA replication, recombination and DNA repair. As the regulation of many aspects of normal cell growth requires the tight control of these processes, it is important to understand how they are influenced by, and interact with, chromatin structure. Much of the regulatory potential of the core histones resides small, positively charged domains called the NH2-terminal tails. The core histone NH2-terminal tails are subject to a wide range of post-translational modifications, of which acetylation is the most extensively characterized. The acetylation of histones, which appears to be a fundamental mechanism by which cells regulate chromatin structure, occurs on lysine residues, negating their positive charge. The acetylation state of the histones is governed by the interplay of enzymes that add acetyl groups (histone acetyltransf erases) and enzymes that remove them (histone deacetylases). Histone acetyltransferases can be divided into two classes based on substrate specificity and cellular localization. Type A histone acetyltransferases are nuclear enzymes that acetylate histones in a chromatin context. Type B histone acetyltransferases acetylate free histones and can be found in the cytoplasm. While type A histone acetyltransferases, such asGcn5p, have been conclusively linked to the regulation of gene expression, little is known about the function of type B histone acetyltransferases. However, using the yeast type B histone acetyltransferase Hat1 p as a model, we have recently obtained evidence that these enzymes are involved in silent chromatin structure and DNA damage repair. The primary goal of our research is to extend these results, using a combination of molecular genetics and biochemistry, to define the in vivo role of type B histone acetyltransferases. This goal will be pursued through three specific aims. The first is to determine the mechanism(s) through which Hat1p affects the silent chromatin structure found near yeast telomeres. The second is to characterize the involvement of Hat1p and chromatin structure the repair of DNA double strand breaks. Third, we will isolate and characterize novel type B histone acetyltransferases.