Structural model of PSIP1-PWWP-H3K36me3 nucleosome complex. (a) Lowest energy structure of the cluster that is in agreement with the cross-validation mutation data. (b) Detailed view showing H3 residues 31to 38 as balls-and-sticks, the DNA in cartoon representation and the van der Waals surface of the PWWP domain color coded by electrostatic potential. (c, d) Detailed view on the intermolecular interactions, focusing on the K36me3 recognition by the aromatic cage (c) and the DNA contacts mediated by K14, K16, K39 and K56 (d, left) and K73, R74 and K75 (d, right). Hydrogen bonds are shown as dashed yellow lines. Color-coding: magenta - PWWP domain, green - H3 tail, grey - DNA. PWWP residues are labeled in black, H3 residues in green. The dashed line in (c) indicates the peptide bond at which the H3 tail was cut in the flexible multi-domain docking protocol.