Type B Histone Acetyltransferases and the Assembly of Chromatin Structure

描述（由申请人提供）：每次真核细胞分裂时，它必须复制，不仅复制其基因组DNA，而且复制其潜在的染色质结构。染色质结构的忠实繁殖对于真核生物基因组的包装和保护以及表观遗传转录程序的维持是必要的。我们研究计划的主要目标是破译染色质的主要蛋白质成分（核心组蛋白H2A， H2B， H3和H3以及连接组蛋白H1）与基因组DNA一起形成染色质的机制。本提案的具体重点是一类被称为B型组蛋白乙酰转移酶的酶的表征。这些酶负责新合成的组蛋白的翻译后乙酰化。虽然几十年来人们已经知道新合成的组蛋白在染色质组装过程中被乙酰化，但这些修饰的功能尚不清楚。我们已经提出了一些研究，将有助于确定B型组蛋白乙酰转移酶Hat1p在染色质组装中的作用。第一个具体目标是利用酿酒酵母作为模型系统研究Hat1p和新合成组蛋白的乙酰化。我们将使用实验系统，使我们能够在几种不同的情况下直接测定Hat1p对染色质组装的影响。此外，将使用多种酵母分子遗传技术来破译新合成的组蛋白上已确定的多个乙酰化位点的独特和重叠功能。最后，我们将继续分离和表征一种新的染色质组装因子，我们已经确定了酵母提取物。第二个特定目标扩展了我们对酵母酶的研究，以表征哺乳动物的Hat1。我们将使用生化技术分离和表征含有人类Hat1酶的复合物。此外，我们将表征Hat1小鼠敲除模型，以确定这种B型组蛋白乙酰转移酶在复杂生物体中的功能。

DESCRIPTION (provided by applicant): Each time a eukaryotic cell divides it must duplicate, not only its genomic DNA, but the underlying chromatin structure, as well. The faithful propagation of chromatin structure is necessary for the packaging and protection of the eukaryotic genome as well as for the maintenance of epigenetically inherited transcriptional programs. The primary goal of our research program is to decipher the mechanisms by which the primary protein components of chromatin (the core histones H2A, H2B H3 and H3 and the linker histone H1) are brought together with genomic DNA to form chromatin. The specific focus of this proposal is the characterization of a class of enzymes known as type B histone acetyltransferases. These enzymes are responsible for the post-translational acetylation of newly synthesized histones. While it has been known for decades that newly synthesized histones are acetylated during the process of chromatin assembly, the function of these modifications is not known. We have proposed a number of studies that will help to identify the role of the type B histone acetyltransferase Hat1p in chromatin assembly. The first specific aim utilizes S. cerevisiae as a model system to study Hat1p and the acetylation of newly synthesized histones. We will use experimental systems that will allow us to directly assay for the effect of Hat1p on chromatin assembly in several different contexts. In addition, will use a variety of yeast molecular genetic techniques to decipher the unique and overlapping functions of the multiple sites of acetylation that have been identified on newly synthesized histones. Finally, we will continue the isolation and characterization of a novel chromatin assembly factor that we have identified in yeast extracts. The second specific aim extends our studies of the yeast enzyme, to the characterization of mammalian Hat1. We will use biochemical techniques to isolate and characterize complexes containing the human Hat1 enzyme. In addition, we will characterize a Hat1 mouse knockout model in order to identify the function of this type B histone acetyltransferase in a complex organism.