A low resolution structure for the histone core of the nucleosome

Abstract
Image reconstruction to 22 Å resolution of the histone octamer (H3)2 (H4)2 (H2A)2 (H2B)2 shows it to have a 2-fold axis of symmetry, and the overall shape of a left-handed helical spool on which to wind about two turns of a flat superhelix of DNA in the nucleosome. From this structure and the results of various cross-linking studies, we have deduced the arrangement of the individual histones. We propose that the (H3)2 (H4)2 tetramer forms a dislocated disk which defines the central turn of DNA, while the two H2A–H2B dimers lie one on each face, each associated with about one half a turn.