a–c, 1.95 Å crystal structure of murine ORC1 BAH aa 9-170 (mORC1BAH) complexed with H4(14-25)K20me2 peptide. a, Ribbon representation of mORC1BAH bound to H4K20me2 peptide. The mORC1BAH (cyan) and the bound H4K20me2 peptide (yellow) are shown in ribbon and stick representations, respectively. b, Details of intermolecular contacts in the mORC1BAH-H4K20me2 complex. mORC1BAH and H4K20me2 peptide residues are colored in pink and yellow, respectively, with hydrogen bonds depicted as red dashed lines, and a water molecular as a red sphere. c, Schematic representation of intermolecular contacts in the mORC1BAH-H4K20me2 complex. The residues from the H4K20me2 peptide and mORC1BAH are colored in magenta and black, respectively. Yellow: the hydrophobic contact. d, Positioning of the K20me2 side chain within an aromatic cage of the indicated residues (red) on the surface of mORC1BAH. The equivalent cage residues in hORC1BAH are labeled in parenthesis. e, Structural overlay of the mORC1BAH K20me2-binding aromatic cage in the free (silver) and H4K20me2-bound states (salmon). Arrows indicate binding-induced structural shifts. f, Mutations in the hORC1BAH H4K20me2-binding channel impair H4K20me2 recognition. ITC analysis of the indicated hORC1BAH mutants binding to H4K20me2 peptide; s.d. derived from non-linear fitting. g–h, Mutations in the hORC1BAH dimethyllysine-binding cage abrogate H4K20me2 recognition. g, Binding assays as in () with the indicated hORC1BAH mutant proteins and biotinylated peptides. h, Top: Western analysis of CTH binding assays as in () with the indicated proteins and antibodies. Bottom: Coomassie blue stain of input GST-fusion proteins and histones (20% of total).