The transcriptional co-activator p300/CBP is involved in gene activation by acetylating histones and other proteins. It can also stimulate transcription by helping RNA polymerase to find the promoter and initiate transcription. George Hunt, Ann Boija and Mattias Mannervik have discovered that this non-enzymatic function of p300/CBP is involved in epigenetic silencing. Recruitment of RNA polymerase to silent gene regions is necessary for nucleosome depletion and formation of RNA-DNA hybrids (R-loops), which allows Polycomb proteins to associated with and maintain these genes in a silent state.

Read the article in Molecular Cell