The eukaryotic genome is tightly compacted in the nucleus as chromatin, with the nucleosome core particle (NCP) as its basic unit, comprising of ~145 base pairs of DNA wrapped around a histone octamer (two copies each of H2A-H2B and H3-H4). Despite this dense packaging, regulatory processes like transcription, replication, and repair must access DNA, necessitating chromatin remodeling. While chromatin is dynamic, the mechanisms enabling such accessibility remain incompletely understood.
Using cryo-electron microscopy (cryo-EM), we visualized chromatin structures in various functional states. Our findings reveal: (i) dynamic rearrangements of nucleosomal DNA and histones during RNA polymerase II-driven transcription elongation; (ii) diverse interactions between chromatin and regulatory proteins involved in transcription, remodeling, modification, repair, immune sensing, and compartmentalization.
This presentation will highlight recent cryo-EM and biochemical insights into how chromatin’s structural flexibility supports its dual role as a dynamic scaffold and a regulatory platform in genome regulation.