Molecular Mechanism of Histone H3/H4 Chaperone Function

描述（由申请人提供）：将基因组包装成染色质对于正常生长、发育和分化至关重要。染色质是一种动态结构，它严格调节所有以DMA为底物的过程，包括转录、DMA复制、DMA修复和重组。此外，染色质组装和拆卸过程在人类疾病中很重要，如在多种遗传畸形以及癌症和白血病亚型中所见，这些亚型与修饰染色质结构的蛋白质畸变有关。负责染色质拆卸和染色质组装的关键蛋白是组蛋白H3和H4伴侣蛋白抗沉默功能1 （Asf1）和染色质组装因子（caf1）复合物。这些蛋白在整个真核生物进化过程中高度保守，是本研究的重点，因为它们在组蛋白H3/H4沉积和核小体分解活动中起着核心作用。本项目的长期目标是在体外和体内统一认识组蛋白H3/H4伴侣之间的关系及其染色质组装和拆卸的机制。第一个目的是利用分子遗传学和结构方法确定Asfl介导的组蛋白H3/H4伴侣蛋白功能的决定因素。第二个目的是利用生物物理分析来研究Asfl的H3/H4伴侣活性的分子机制。第三个目标是深入了解中心DNA复制依赖的染色质组装因子-三亚基caf1复合物的功能及其与Asfl的相互作用，以建立染色质组装的分子机制。这些研究将利用我们最近的Asf1-H3/H4晶体结构，我们已经产生的重组染色质组装因子，以及对出芽酵母模型系统的生理分析。通过将PI和Co-Pi在生物物理学、结构生物学、遗传学和生物化学方面的个人专业知识结合和应用于组蛋白H3/H4伴侣蛋白的合作研究，我们处于一个独特的位置，可以在详细了解组蛋白伴侣蛋白活性的分子基础方面取得重要进展。这项工作将填补目前对染色质组装和拆卸这些基本过程的理解中的关键空白，这些过程对所有依赖dma的细胞功能至关重要。与公共卫生有关。许多疾病都是基因表达错误的结果。对染色质组装和拆卸的分子和结构的理解将来自这项工作，这将进一步提高我们修改与人类疾病有关的表观遗传密码的能力，以达到治疗干预的目的。

DESCRIPTION (provided by applicant): The packaging of the genome into chromatin is essential for normal growth, development, and differentiation. Chromatin is a dynamic structure that tightly regulates all of the processes that use DMA as a substrate, including transcription, DMA replication, DMA repair, and recombination. Furthermore, chromatin assembly and disassembly processes are important in human disease, as seen in the multiple genetic malformations, as well as cancer and leukemia subtypes that have been linked to aberrations in proteins that modify chromatin structure. The key proteins responsible for chromatin disassembly and chromatin assembly are the histone H3 and H4 chaperones Anti-silencing function 1 (Asf1) and the Chromatin Assembly Factor (CAF-1) complex. These proteins are highly conserved throughout eukaryotic evolution and are the focus of this study because of their central role in histone H3/H4 deposition and nucleosome disassembly activities. The long-term goal of this project is to gain a unified understanding of the relationship among histone H3/H4 chaperones and their mechanism of chromatin assembly and disassembly in vitro and in vivo. The first Aim is to define the determinants of Asfl -mediated histone H3/H4 chaperone function using molecular genetics and structural approaches. The second Aim is to investigate the molecular mechanism of the H3/H4 chaperone activity of Asfl using biophysical analyses. The third Aim is to gain key insight into the function of the central DNA replication-dependent chromatin assembly factor - the trisubunit CAF-1 complex, and its interactions with Asfl to establish the molecular mechanism of chromatin assembly. These studies will take advantage of our recent Asf1-H3/H4 crystal structure, recombinant chromatin assembly factors that we have already generated, and physiological analyses in the budding yeast model system. By combining and applying the individual expertise of the PI and Co-Pi in biophysics, structural biology, genetics and biochemistry to this collaborative study of histone H3/H4 chaperones, we are in a unique position to make important strides toward a detailed understanding of the molecular basis of histone chaperone activity. This work will fill critical gaps in the current understanding of these fundamental processes of chromatin assembly and disassembly, which are essential and central to all DMA-dependent cellular functions. Relevance to the public health. Many diseases are the result of incorrect gene expression. The molecular and structural understanding of chromatin assembly and disassembly that will come from this work will further our ability to modify the epigenetic codes involved in human diseases for the purpose of therapeutic intervention.