Extended Data Fig. 2: Comparison of the structures of vPRC1 and RING1B-UBCH5C:BMI1 bound to an unmodified nucleosome.
From: Structural basis of the histone ubiquitination read–write mechanism of RYBP–PRC1
Top left, superposition of the vPRC1:Nuc complex cryo-EM structure in this study and the RING1B-UBCH5C:BMI1:Nuc complex structure (PDB: 4R8P) previously determined by X-ray crystallography5. The two structures were superimposed via H2A but for clarity in the overview only the nucleosome model determined by cryo-EM is shown. Below, zoom-in view of the RING1B/H2A acidic patch interface; right, zoom-in view of the BIM1/H2B-H3 interface. The vPRC1 cryoEM structure follows the same color code as depicted in Fig. 1 and the PDB: 4R8P structure is shown in lighter shades of the same colors. Note that McGinty et al used a RING1B-UBCH5C fusion protein in complex with BMI1 to stabilize the complex on the nucleosome; UBCH5C is shown in teal. The superposition illustrates that the RING1B:BMI1 ring finger heterodimer in the two structures engages with the nucleosome acidic patch with a highly similar binding geometry and through the identical amino acid contacts.
