Fig. 3: The Ioc3 subunit reduces nucleosome mobilization by promoting backtracking of Isw1.

a DNA movement during remodeling of 0N70 nucleosomes was tracked by mapping DNA contacts with histones by modifying residue 45 of histone H2A (red arrow) and photocrosslinking DNA as depicted. Two sides of the dyad axis are tracked by labeling either the upper or lower strands with ³²P at the 5′ end of DNA. The labeled strand is shown in black and the unlabeled strand in gray. Shown in the schematic is the nucleosome movement on DNA when remodeled either by ISW1a or Isw1 and the starting contact point is referred to as zero. The bound location of the ATPase domain is shown in blue. The remodeled nucleosome positions are shown along with an outline of the original nucleosome for reference. b, c The phosphorimages are shown for (b) ISW1a and (c) Isw1 samples analyzed on a 6% polyacrylamide with 8 M urea. Nucleosomes with the upper (lanes 1–6) or lower (lanes 7–12) DNA strands labeled were separately analyzed and experiments were done with n = 3 independent replicates.