The three-dimensional structure of chromatin condensed by PRC1 is porous and accessible [ATAC-seq]

ABSTRACT: The compaction of chromatin is a prevalent paradigm in gene repression. Chromatin compaction is commonly thought to repress transcription by restricting chromatin accessibility. However, the spatial organisation and dynamics of chromatin compacted by gene-repressing factors are unknown. Using cryo-electron tomography, we solved the three-dimensional structure of chromatin condensed by the Polycomb Repressive Complex 1 (PRC1) in a complex with CBX8. Unexpectedly, PRC1-condensed chromatin is porous and forms a size-selective diffusion barrier that is stabilised through multivalent dynamic interactions. Accordingly, PRC1 remains dynamic within the condensate while maintaining the chromatin static. In differentiated mouse embryonic stem cells, CBX8-bound chromatin remains accessible. These findings challenge the idea of open and closed chromatin states and instead suggest that PRC1 permits size-selective accessibility of macromolecules into chromatin condensates.

ORGANISM(S): Mus musculus

PROVIDER: GSE220138 | GEO | 2024/03/07

REPOSITORIES: GEO