Biophysics of Macromolecular Complexes

大分子复合物的生物物理学

• 批准号: 8349728
• 负责人: Gary Felsenfeld
• 金额: $ 26.36万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8349728
• 关键词: Affinity; Architecture; Binding; Biochemical; Biological; Biological Assay; Biological Models; Biophysics; Carbohydrates; Cell Nucleus; Cell physiology; Cells; Chromatin; Chromatin Fiber; Chromatin Structure; Chromosome Structures; Chromosomes; Collaborations; Complement; Cultured Cells; DNA; DNA biosynthesis; Disaccharides; Gene Expression; Genes; Genetic; HIV; HIV Envelope Protein gp120; HIV-1; Heterochromatin; Investigation; Laboratories; Lectin; Link; Macromolecular Complexes; Mannose; Membrane Proteins; Methods; Modeling; Molecular; Molecular Biology; Molecular Conformation; National Institute of Diabetes and Digestive and Kidney Diseases; Nucleic Acids; Physical condensation; Play; Process; Property; Proteins; Publishing; Resolution; Role; Shapes; Structure; arm; beta Globin; folate-binding protein; in vitro Model; in vivo; interest; macromolecular assembly; member; monomer; prevent; protein complex; stoichiometry

Chromatin structure and architecture. DNA within the cell nucleus is packaged into chromatin and a variety of models presently describe the structure of the condensed 30 nm chromatin fiber. We are specifically interested in an understanding of the topological organization of DNA within condensed 30 nm chromatin fragments. In order to do this we are currently developing high resolution chromosome capture conformation assays utilizing both in vitro model systems, as well as native chromatin fragments, such as the previously studied condensed heterochromatin flanked by the developmentally regulated folate receptor and beta-globin genes. These studies will allow us to determine the structure of the 30 nm chromatin fiber, which will in turn provide a better understanding of the relations between chromatin structure and essential processes such as gene expression and DNA replication. Macromolecular assemblies. In collaboration with members of the Laboratory of Molecular Biology, and others, protein and protein-nucleic acid assemblies have been characterized in terms of their shape, stoichiometry and affinity of interaction using hydrodynamic methods. These studies extend current biochemical and structural investigations as exemplified by recently published studies on the monovalent lectin microvirin carried out in collaboration with Drs. G. Marius Clore and Carole Bewley. In this study, purified microvirin was shown to exist as a monodisperse monomer which binds monovalently to mannose alpha(1-2) mannose with an affinity of 50 micromolar. As this disaccharide unit terminates the arms of high mannose N-linked carbohydrate chains, microvirin is able to interact with the highly glycosylated HIV-1 surface protein gp120 and prevent HIV-1 entry into cultured cells. These biophysical and structural studies illustrate the molecular mechanism through which microvirin inhibits HIV entry (Shahzad-ul-Hussan et al., 2011).

染色质结构和架构。 细胞核内的DNA被包装成染色质，目前有多种模型描述了浓缩的30 nm染色质纤维的结构。 我们特别感兴趣的是在压缩的30纳米染色质片段内的DNA拓扑组织的理解。 为了做到这一点，我们目前正在开发高分辨率的染色体捕获构象分析，利用体外模型系统，以及天然染色质片段，如以前研究的浓缩异染色质侧翼发育调节叶酸受体和β-珠蛋白基因。 这些研究将使我们能够确定30 nm染色质纤维的结构，这反过来又将更好地理解染色质结构与基因表达和DNA复制等基本过程之间的关系。 大分子组装体。 在与分子生物学实验室的成员和其他人的合作中，蛋白质和蛋白质-核酸组装体已经使用流体动力学方法在它们的形状、化学计量和相互作用亲和力方面进行了表征。 这些研究扩展了当前的生物化学和结构研究，最近发表的与G。马里乌斯·克洛和卡罗尔·比尤利 在这项研究中，纯化的微病毒蛋白显示作为单分散单体存在，其以50微摩尔的亲和力将单核苷酸与甘露糖α（1-2）甘露糖结合。 由于该二糖单元终止高甘露糖N-连接的碳水化合物链的臂，因此微病毒蛋白能够与高度糖基化的HIV-1表面蛋白gp 120相互作用，并阻止HIV-1进入培养细胞。 这些生物物理和结构研究说明了微病毒蛋白抑制HIV进入的分子机制（Shahzad-ul-Hussan et al.，2011年）。