Epigenetic maintenance of PRC2-repressed chromatin requires RTT109 but not H3K56 acetylation.

RTT109 is essential for maintaining PRC2-repressed chromatin in Neurospora crassa, independent of H3K56 acetylation, highlighting a novel epigenetic inheritance mechanism.

• Why it matters: Understanding how repressed chromatin states are stably inherited is crucial for insights into gene regulation and epigenetic memory across organisms.
• What they did: The study used genetic and biochemical approaches to show that RTT109’s catalytic activity, not H3K56 acetylation or NAF-2 interaction, is necessary for PRC2-mediated H3K27me3 maintenance over multiple cell divisions.
• The result: Findings reveal that RTT109 supports the propagation of repressive chromatin states through a replication-linked mechanism, advancing knowledge of epigenetic inheritance and Polycomb complex regulation.