Protein-Protein and Protein-DNA Interfaces of the Nucleosome

核小体的蛋白质-蛋白质和蛋白质-DNA 界面

• 批准号: 0091736
• 负责人: Evangelos Moudrianakis
• 金额: $ 36万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-15 至 2006-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0091736&HistoricalAwards=false
• 关键词: Protein; DNA; Interfaces; Nucleosome

Moudrianakis0091736The goal of the this research is to elucidate the properties that govern the relations between the structure of the nucleosome and the functional remodeling (transitions between assembly and disassembly) that occurs during the cell cycle. The approach is based on integrated applications of classical biochemistry and biophysical chemistry with those of molecular genetics. This approach addresses the basic properties of both nucleosomal DNA and the octameric histone core within a dynamic structure. New evidence from the PI's laboratory (based on molecular dynamics calculations) suggests that the nucleosome is very dynamic, exhibiting large "breathing" motions in the nanosecond time scale and that the contact interfaces between the protein subunits show time-dependent fluctuations. The protein core is an "articulated endoskeleton" around which the DNA wraps in a "generic, non base-specific way" for most of its length, with relatively few site-specific contacts. Such a "fragile" arrangement serves the needs of regulation well; it is mediated to a large extent by the subunit contacts within the core histone octamer. These studies are examining a range of conditions that affect the intrinsic (molecular types) and extrinsic (microenvironment) parameters of native heterodimers and their assembly potential. This is important because a thorough understanding of the functional transitions of the nucleosome/chromatin entailed during chromatin remodeling, replication and transcription depends on the exact knowledge of the energetics and specificities of these interfacial contacts. Techniques to be employed are: analytical ultracentrifugation, high-resolution multi-angle light scattering and microcalorimetry as well as contemporary methods of analytical chemistry.

Moudrianakis0091736这项研究的目标是阐明控制核小体结构与细胞周期中发生的功能重塑（组装和分解之间的转变）之间关系的特性。 该方法基于经典生物化学和生物物理化学与分子遗传学的综合应用。该方法解决了动态结构内核小体 DNA 和八聚组蛋白核心的基本特性。 PI实验室的新证据（基于分子动力学计算）表明核小体非常动态，在纳秒时间尺度内表现出大的“呼吸”运动，并且蛋白质亚基之间的接触界面显示出随时间变化的波动。蛋白质核心是一个“铰接的内骨骼”，DNA在其大部分长度上以“通用的、非碱基特异性的方式”包裹在其周围，而位点特异性接触相对较少。 这种“脆弱”的安排很好地满足了监管的需要；它在很大程度上是由核心组蛋白八聚体内的亚基接触介导的。 这些研究正在研究影响天然异二聚体的内在（分子类型）和外在（微环境）参数及其组装潜力的一系列条件。这很重要，因为对染色质重塑、复制和转录过程中所需的核小体/染色质功能转变的透彻理解取决于对这些界面接触的能量和特异性的准确了解。所采用的技术包括：分析超速离心、高分辨率多角度光散射和微量热法以及现代分析化学方法。