Sampled configurations of a 177×12 array bearing undertwisted nucleosomes.

This video - found in the accompanying mp4 file - shows successive configurations of an array bearing twelve evenly spaced, rigid nucleosomes generated by Markov-Monte Carlo sampling of deformable base-pair steps along the intervening linker DNAs. The nucleosomal segments are constrained to the undertwisted pathway found in the currently best-resolved nucleosome core particle structure (PDB file 1kx5 (3)). The base-pair steps along the protein-free DNA linkers are subject to room-temperature fluctuations; see Refs. (9, 11, 12, 24) for details of model building and energy calculations.