NSF Award
1515346
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. <br/><br/>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nucleosomes (DNA-protein building blocks of higher-order chromatin) in which the typical protein histone H3 has been replaced by a related histone known as CENP-A. This replacement is presumed to confer new structural organization to the centromere, thereby enabling it to be recognized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. <br/><br/>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.
