Figure 4.

(A) Optimal two-dimensional correlation docked result of multiple copies of the histone octamer crystal structure into the reconstruction, using both helical and dyad axis constraints. The result is truncated to two rings for display purposes. Dyad axes (red arrows) point toward the helical axis, whereas adjacent spiral axes (blue arrows) intersect each other to form a pseudocontinuous left-handed heterodimer spiral. (B) Two-dimensional cross-correlation surface, produced by the constrained docking shown in A. The surface displays a peak at a helical diameter of 320 Å, and a dyad rotation of 0°.