Modulation of nucleosome dynamics

核小体动力学的调节

• 批准号: 7642373
• 负责人: Andrew Joseph Andrews
• 金额: $ 5.01万
• 依托单位: COLORADO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7642373
• 关键词: Address; Affect; Affinity; Binding; Binding Sites; Biological Models; Cell Nucleus; Cell Survival; Cells; Chromatin; Complex; DNA; DNA Probes; DNA-Protein Interaction; Data; Gene Expression; Genetic Transcription; Goals; Histone H1; Histone H1(s); Histone H2A; Histone H3; Histones; Knowledge; Linker DNA; Location; Measures; Mediating; Methods; Molecular Chaperones; Nucleosomes; Play; Property; Proteins; RNA Polymerase II; Regulation; Research; Role; Structure; Testing; Thermodynamics; Variant; X-Ray Crystallography; dimer

DESCRIPTION (provided by applicant): The nucleosome is the building block of chromatin, the condensed form of DMA found in the cell nucleus. First, a tetramer of histones H3 and H4 binds to DNA to form the tetrasome, which then binds two H2A-H2B dinners to form the nucleosome. This structure is further compacted by the linker histone (H1) that binds the linker DNA, further compacting the DNA and limiting protein-DNA interactions that are necessary for gene expression. Regulation of chromatin dynamics is critical for cell survival. Herein I propose to investigate two ATP-independent ways in which the cell regulates chromatin dynamics and thereby DNA accessibility: the incorporation of histone variants into nucleosomes and the role of histone chaperones in DNA accessibility. Specific histone dimer variants are often found near locations of active transcription (gene expression); therefore, histone variants are thought to be more dynamic thereby facilitating efficient DNA-protein interactions. Furthermore, histone dimer variants may form less compact, or partial, nucleosomes. These partial nucleosomes (or hexasomes) have been observed as intermediates during transcription. Altering the free concentration of dimers could facilitate the formation of these partial nucleosomes. Therefore, a second method for the cell to regulate chromatin dynamics is through the use of histone chaperones to control the free histone concentration. I propose to use Nucleosome Assembly Protein 1 (NAP1) as a means to control free histone concentrations, to measure the affinity and cooperativity of histone dimers and variants, and to probe DNA accessibility to proteins. These studies will aid our understanding of the differences in chromatin dynamics between nucleosomes containing major type and variant dimer histones, including examination of these properties under sub-saturating conditions, which may exist during transcription. Additionally, I will probe the roles of the linker histone H1 and NAP1 in chromatin dynamics, and define the NAP1-H1 interaction using X-ray crystallography. The results from these studies will enhance our knowledge of how proteins gain access to nucleosomal DNA and how cells regulate this by controlling free histone concentrations. These data should also aid in our understanding of transcription in the context of chromatin.

描述（由申请人提供）：核小体是染色质的组成部分，染色质是细胞核中发现的 DMA 的浓缩形式。首先，组蛋白 H3 和 H4 的四聚体与 DNA 结合形成四聚体，然后四聚体结合两个 H2A-H2B 晚餐形成核小体。该结构通过结合接头 DNA 的接头组蛋白 (H1) 进一步压缩，从而进一步压缩 DNA 并限制基因表达所需的蛋白质-DNA 相互作用。染色质动力学的调节对于细胞生存至关重要。在此，我建议研究细胞调节染色质动力学从而调节 DNA 可及性的两种不依赖于 ATP 的方式：将组蛋白变体掺入核小体以及组蛋白伴侣在 DNA 可及性中的作用。特定的组蛋白二聚体变体经常出现在活跃转录（基因表达）位置附近；因此，组蛋白变体被认为更具动态性，从而促进有效的 DNA-蛋白质相互作用。此外，组蛋白二聚体变体可能形成不太紧凑或部分核小体。这些部分核小体（或六体）已被观察为转录过程中的中间体。改变二聚体的游离浓度可以促进这些部分核小体的形成。因此，细胞调节染色质动力学的第二种方法是通过使用组蛋白伴侣来控制游离组蛋白浓度。我建议使用核小体组装蛋白 1 (NAP1) 作为控制游离组蛋白浓度、测量组蛋白二聚体和变体的亲和力和协同性以及探测 DNA 对蛋白质的可及性的手段。这些研究将帮助我们了解含有主要类型和变异二聚体组蛋白的核小体之间染色质动力学的差异，包括在转录过程中可能存在的亚饱和条件下检查这些特性。此外，我将探讨连接子组蛋白 H1 和 NAP1 在染色质动力学中的作用，并使用 X 射线晶体学定义 NAP1-H1 相互作用。这些研究的结果将增强我们对蛋白质如何接触核小体 DNA 以及细胞如何通过控制游离组蛋白浓度来调节核小体 DNA 的了解。这些数据还应该有助于我们理解染色质背景下的转录。