Binding of PHF1 Tudor to H3K36me3 enhances nucleosome accessibility

The Tudor domain of human PHF1 recognizes trimethylated lysine 36 of histone H3 (H3K36me3). This interaction modulates the methyltransferase activity of the PRC2 complex and has a role in retention of PHF1 at DNA damage sites. We have previously determined the structural basis for the association of Tudor with a methylated histone peptide. Here we detail the molecular mechanism of binding of the Tudor domain to the H3K C 36me3-nucleosome core particle (H3K C 36me3-NCP). Using a combination of TROSY NMR and FRET, we show that Tudor concomitantly interacts with H3K36me3 and DNA. Binding of the PHF1 Tudor domain to the H3K C 36me3-NCP stabilizes the nucleosome in a conformation in which the nucleosomal DNA is more accessible to DNA-binding regulatory proteins. Our data provide a mechanistic explanation for the consequence of reading of the active mark H3K36me3 by the PHF1 Tudor domain. Binding of the Tudor domain of the PHD finger protein PHF1 to H3K36me3 inhibits Polycomb PRC2 complex methyltransferase activity. Here, Musselman et al. characterize this interaction in the context of the full nucleosome and show dual binding of the PHF1 Tudor domain to H3K36me3 and double-stranded DNA.