Phase separation and nucleosome compaction are governed by the same domain of Polycomb Repressive Complex 1

BioRxiv : the Preprint Server for Biology
Aaron J PlysRobert E Kingston

Abstract

Mammalian development requires effective mechanisms to repress genes whose expression would generate inappropriately specified cells. The Polycomb Repressive Complex 1 (PRC1) family complexes are central to maintaining this repression. These include a set of canonical PRC1 complexes that each contain four core proteins, including one from the CBX family. These complexes have previously been shown to reside in membraneless organelles called Polycomb bodies, leading to speculation that canonical PRC1 might be found in a separate phase from the rest of the nucleus. We show here that reconstituted PRC1 readily phase separates into droplets in vitro at low concentrations and physiological salt conditions. This behavior is driven by the CBX2 subunit. Point mutations in an internal domain of CBX2 eliminate phase separation. These same point mutations eliminate the formation of puncta in cells, and have previously been shown to eliminate nucleosome compaction in vitro and to generate axial patterning defects in mice. Thus, a single domain in CBX2 is required for phase separation and nucleosome compaction, a finding that relates these functions to each other and to proper development.

Related Concepts

Cell Nucleus
Enzyme Repression
Laboratory mice
Polycomb
Internal
Cbx2 protein, mouse
Nucleosome Location
Protein Expression
PRC1 Protein
NKRF gene

Related Feeds

BioRxiv & MedRxiv Preprints

BioRxiv and MedRxiv are the preprint servers for biology and health sciences respectively, operated by Cold Spring Harbor Laboratory. Here are the latest preprint articles (which are not peer-reviewed) from BioRxiv and MedRxiv.