The Role of Histone Chaperones in Histone Acetylation and Nucleosome Dynamics

项目总结 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。众多因素中的两个 保持这种平衡的是组蛋白和组蛋白结合蛋白。组蛋白最终要对 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的联系 猫咪和组蛋白伴侣。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。为了阐明这些机制(S)，我们是 研究酵母和人类两个组蛋白伴侣蛋白家族NAP1和Asf1之间的关系， 以及相应的Kat、Rtt109(酵母)、CBP和p300(人)。Rtt109是的结构同源 CBP/p300，并且这两个KAT在功能上都与组蛋白伴侣蛋白NAP1和ASF1家族相连。我们有 证实了组蛋白伴侣蛋白(ASF1)识别组蛋白乙酰化状态和做功的能力 共同改变KATS的特异性。我们建议这些伴侣的功能是维持 通过调节哪些赖氨酸被乙酰化以及它们在染色质中的掺入来调节染色质的适当乙酰化 染色质。目前对特异性和选择性如何实现的生物化学和分子理解是 这是染色质领域的一大挑战。本项目将采用并扩展新的研究方法 复杂的蛋白质-蛋白质网络需要调节染色质的动态和翻译后的特异性。

PROJECT SUMMARY 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 elucidate these mechanism(s) we are studying the relationships between two families of histone chaperones in yeast and humans, Nap1 and Asf1, and their corresponding KATs, Rtt109 (yeast) and CBP and p300 (human). Rtt109 is the structural homolog of CBP/p300, and both KATs are functionally linked to the Nap1 and Asf1 families of histone chaperones. We have demonstrated the ability of histone chaperones (Asf1), to recognize the acetylation state of histones and work together to modify the specificity of KATs. We are proposing that these chaperones function to maintain the proper acetyl-profiles of chromatin by regulating both which lysines get acetylated and their incorporation in to chromatin. 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.