Fig. 1

Structural plasticity of the nucleosome core particle (NCP). a Cryo-EM maps of the NCP in two distinct conformations. Class 1 (left, blue) resembles canonical nucleosome, whereas Class 2 (right, red) is in distorted conformation. Class 1 is resolved to 3.85 Å and Class 2 to 4.05 Å (0.143 cutoff in FSC curve). Class 1 contains 51 000 particles and Class 2 contains 58 000 particles. b Global changes in the nucleosome structure. Comparison of X-ray structure (PDB:3LZ1) and Class 2 (distorted nucleosome) models. The nucleosome core particle contracts along the symmetry axis by 8% (distance between nucleotides 2 and 38) and expands in the perpendicular direction by 5% (distance between nucleotides 17 and 58). c RMSD between the X-ray structure (PDB:3LZ1) and the Class 2 model, showing the extent of rearrangements in the NCP. The X-ray structure and the Class 2 model were superimposed and RMSD of Cα was calculated and depicted. DNA at SHL 1–2 and SHL 6–7 shows the largest movements between these two structures (> 4 Å). H3 α1, α2, and α3 show the largest rearrangements in the histone octamer