A Bridging Model for Persistence of a Polycomb Group Protein Complex through DNA Replication In Vitro

作者：Lo Stanley M; Follmer Nicole E; Lengsfeld Bettina M; Madamba Egbert V; Seong Samuel; Grau Daniel J; Francis Nicole J^*

来源：Molecular Cell, 2012, 46(6): 784-796.

DOI：10.1016/j.molcel.2012.05.038

Epigenetic regulation may involve heritable chromatin states, but how chromatin features can be inherited through DNA replication is incompletely understood. We address this question using cell-free replication of chromatin. Previously, we showed that a Polycomb group complex, PRC1, remains continuously associated with chromatin through DNA replication. Here we investigate the mechanism of persistence. We find that a single PRC1 subunit, Posterior sex combs (PSC), can reconstitute persistence through DNA replication. PSC binds nucleosomes and self-interacts, bridging nucleosomes into a stable, oligomeric structure. Within these structures, individual PSC-chromatin contacts are dynamic. Stable association of PSC with chromatin, including through DNA replication, depends on PSC-PSC interactions. Our data suggest that labile individual PSC-chromatin contacts allow passage of the DNA replication machinery while PSC-PSC interactions prevent PSC from dissociating, allowing it to rebind to replicated chromatin. This mechanism may allow inheritance of chromatin proteins including PRC1 through DNA replication to maintain chromatin states.

• 出版日期2012-6-29