Title：Assembly required: Polycomb proteins in a cold-induced epigenetic switch

Speaker：Dr. Anna Schulten （John Innes Centre）

Time: 10:00-11:30 AM, 28 Apr., 2025

Venue: Room 315, Research building 1

Abstract:

Multivalent protein-chromatin interactions facilitated by higher-order protein assemblies are emerging as a crucial theme in eukaryotic gene regulation. Arabidopsis VEL proteins undergo assembly by head-to-tail polymerization. Here, we dissect the role of VEL polymerization domains of VIN3 and VRN5 in conferring epigenetic silencing of the Arabidopsis FLOWERING LOCUS C (FLC) via the Polycomb Repressive Complex 2 (PRC2). We show that VIN3 VEL polymerization involves higher-order VIN3 assemblies in vivo, promotes multivalent chromatin association and PRC2-mediated H3K27me3 deposition. The VRN5 VEL domain is unable to functionally replace VIN3 VEL, but has a role in physically connecting VIN3 with the PRC2 complex. This work reveals how a VEL polymerization-mediated assembly of Polycomb proteins cooperatively promotes epigenetic silencing.

Introduction:

Anna Schulten is a senior postdoc in the lab of Prof. Caroline Dean at the John Innes Centre in Norwich, UK. She studies the mechanisms underlying epigenetic switching at the Arabidopsis floral repressor gene FLC, which is epigenetically silenced by exposure to winter cold during vernalization. In 2019, Anna obtained her PhD in the lab of Prof Ute Krämer in Germany, where the investigated a transcription factor involved in plant copper homeostasis."