Fassberg Seminar: Heterochromatin organization and dynamics

DNA is wrapped around nucleosomes, forming chromatin chains that are further organized in three-dimensional assemblies. The architecture of these assemblies is crucial in determining cell transcriptional programs. Yet, the principles that underlie and regulate the architecture and organization of chromatin are poorly understood. I will present hydrogen-deuterium exchange, NMR, and mass-spectrometry data illustrating how HP1 proteins drive chromatin compaction into heterochromatin. I will propose a model for heterochromatin organization in which HP1 proteins couple chromatin compaction and phase separation by increasing the accessibility and dynamics of nucleosomes. I will further discuss the biophysical and biological implications of the proposed model in chromatin assemblies beyond heterochromatin.