FIG. 3.

(Color online) Elastic-rod models of DNA, depicted as a line, partially wound around a cylindrical representation of the histone octamer, depicted as a partially transparent cylinder, at a force of 8 pN for three different winding (2α) and rotation (β) angles: 2α= 4.8 radians and β = 2.33 radians (top), 2α = 4.18 radians and β = 1.46 radians (middle), and 2α = 3.7 radians and β = 0.65 radians (bottom). DNA in contact with the nucleosome is shown lighter than the DNA not in contact with the nucleosome. The angle subtended by this DNA defines the winding angle 2α, as indicated in the bottom panel. The rotation angle (β) of the cylinder axis about the vertical axis is indicated in each panel. Axes are marked in nanometers.