The Role of Histone Chaperones in Histone Acetylation and Nucleosome Dynamics

项目摘要/摘要 在每个真核细胞的细胞核中都有一个根本的悖论：遗传物质必须是 组织和压缩，但仍可由转录机器读出。众多中的两个 保持这种平衡的因素是组蛋白和组蛋白结合蛋白。组蛋白是最终负责的 将染色体DNA压缩近500,000倍以适应细胞核。虽然基因组可获得性是 部分受组蛋白乙酰转移酶(KATS)调节，组蛋白伴侣蛋白直接与 组蛋白，并可以在DNA上组装和/或分解它们。KATS共价修饰组蛋白和 因此有可能改变染色质结构。令人振奋的新证据在结构和功能上 将Kats和组蛋白伴侣联系起来。然而，人们对这些机制几乎一无所知。 蛋白质相互协作来管理紧凑和基因组的可及性。开始理解这一点很重要 生物学问题，本课题提出以组蛋白乙酰转移酶(KAT)Rtt109为模型进行研究 系统。Rtt109使用两个结构上不相关的组蛋白伴侣蛋白，Vps75和ASF1。在体内，Vps75具有 已经被证明与Rtt109直接相互作用，但Rtt109的功能只需要ASF1。两个伴侣 在体外激活Rtt109乙酰转移酶活性，但Rtt109乙酰化多个位置的组蛋白，以及 Vps75和ASF1似乎改变了Rtt109的特异性。对生物化学和分子生物学的理解 实现特异性和选择性是目前染色质领域的一大挑战。这个项目将 采用和扩展研究需要调节的复杂蛋白质-蛋白质网络的新方法 染色质动力学和翻译后特异性。

PROJECT SUMMARY/ABSTRACT There is a fundamental paradox within the nucleus of every eukaryotic cell: The genetic material must be organized and compacted yet remain accessible for readout by transcription machinery. Two of the many factors that retain this balance are histones and histone binding proteins. Histones are ultimately responsible for compacting the chromosomal DNA almost 500,000-fold to fit into the nucleus. While genome accessibility is regulated in part by the actions of histone acetyltransferases (KATs), histone chaperones interact directly with histones and can assemble and/or disassemble them on DNA. KATs covalently modify the histones and therefore have the potential to alter chromatin structure. Exciting new evidence structurally and functionally link KATs and histone chaperones. However, virtually nothing is known about the mechanisms by which these proteins cooperate to manage compaction and genome accessibility. To begin to understand this important biological question, this project proposes to study the histone acetyltransferase (KAT) Rtt109 as a model system. Rtt109 employs two structurally unrelated histone chaperones, Vps75 and Asf1. In vivo, Vps75 has been shown to directly interact with Rtt109, but only Asf1 is required for Rtt109 function. Both chaperones activate Rtt109 acetyltransferase activity in vitro, but Rtt109 acetylates histones in multiple locations, and Vps75 and Asf1 appear to alter Rtt109 specificity. A biochemical and molecular understanding of how specificity and selectivity is achieved is currently a major challenge in the chromatin field. This project will employ and expand on new methodologies for studying complex protein-protein networks needed to regulate chromatin dynamics and post-translational specificity.