Nanoscale Structure and Dynamics of Chromatin

这项研究的目标是促进对着丝粒结构和组装的基本了解，着丝粒是染色体的专门片段，使它们能够在细胞分裂期间准确分离。该项目将利用尖端的分子生物物理学方法来探索着丝粒组织相对于染色体其他部分的关键差异。科学和技术进步将纳入本科生和研究生的实践研究培训，并将纳入结构生物学和生物物理学的正式课程。将最先进的技术应用于染色体生物学的中心问题，不仅有望激发学生对基础科学的兴趣，还将为他们在生物学和物理学交界处的职业生涯做好准备。在真核细胞中，在细胞分裂过程中复制的染色体的准确分离是由着丝粒调节的。如果着丝粒受损或被移除，染色体就会随机分离，从而扰乱细胞分裂过程。着丝粒与其他染色体的不同之处在于含有核小体(高阶染色质的DNA-蛋白质构建块)，其中典型的组蛋白H3已被称为CENP-A的相关组蛋白取代。这种替代被推定为赋予着丝粒新的结构组织，从而使其能够被隔离机制识别。然而，关于高度特异性识别的结构和机制的细节仍然不确定。该项目的研究旨在促进对着丝粒染色质结构的所有组织水平的了解，特别是了解着丝粒与染色体的非着丝粒区域的结构特征。高分辨率原子力显微镜(AFM)研究将被用来评估着丝粒染色质在不同组织水平上的结构。单核小体和核小体阵列将使用尖端的高速AFM直接可视化，使水溶液中具有视频速率时间分辨率的纳米级动态成像成为可能。实验数据将得到高功率计算分析的补充。这种结合的方法将为着丝粒、核小体和核小体阵列的结构和动力学提供新的线索，并将有助于理解着丝粒结构与其在染色体分离过程中的功能之间的关系。该项目由分子和细胞生物科学司的遗传机制方案和生物科学局的新兴前沿司以及数学和物理科学局物理司的生命系统物理学方案共同资助。

The goal of this research is to advance fundamental understanding of the structure and assembly of centromeres, the specialized segments of chromosomes that allow them to separate accurately during cell division. The project will take advantage of cutting-edge molecular biophysics approaches to probe key differences in the organization of centromeres, relative to other parts of chromosomes. Scientific and technological advances will be integrated into hands-on research training for undergraduate and graduate students and will be incorporated into a formal course of study in structural biology and biophysics. Application of state-of-the art technology to central questions in chromosome biology is expected not only to inspire student interest in basic science, but also to prepare them for careers at the interface of biology and physics. In eukaryotic cells, accurate segregation of replicated chromosomes during cell division is mediated by centromeres. If centromeres become damaged or removed, chromosomes segregate randomly, thus disrupting the cell division process. Centromeres differ from the rest of the chromosomes by containing nucleosomes (DNA-protein building blocks of higher-order chromatin) in which the typical protein histone H3 has been replaced by a related histone known as CENP-A. This replacement is presumed to confer new structural organization to the centromere, thereby enabling it to be recognized by the segregation machinery. However, details about the structure and the mechanism underlying the highly specific recognition remain uncertain. The studies in this project are designed to advance knowledge of centromere chromatin structure at all levels of its organization and especially to understand what structural features distinguish centromeres from non-centromeric regions of chromosomes. High-resolution atomic force microscopy (AFM) studies will be used to assess the structure of centromere chromatin at different levels of organization. Single nucleosomes and nucleosome arrays will be visualized directly with the use of cutting-edge high-speed AFM, enabling dynamic imaging in aqueous solution at nanoscale with video-rate temporal resolution. The experimental data will be supplemented by high-power computational analysis. This combined approach will shed new light on the structure and dynamics of centromere nucleosomes and nucleosome arrays and will lead to understanding the relationship between centromere structure and its function during the chromosomal segregation process. This project is co-funded by the Genetic Mechanisms Program in the Division of Molecular and Cellular Biosciences and by the Emerging Frontiers Division, both in the Biological Sciences Directorate, and by the Physics of Living Systems Program in the Physics Division in the Mathematical and Physical Sciences Directorate.