Figure 7. The interacting barrier model for specific nucleosome placement by Isw2.

(A) A DNA binding factor with an Isw2-recruitment helix (or other epitope) associates with DNA. The WAC domain of Itc1 engages with the recruitment epitope to proximally align the catalytic subunit of Isw2 with the proper nucleosome. (B) Nucleosome sliding by Isw2 creates a nucleosome position that is too close to the recruitment epitope for proper alignment of the recruitment epitope – Itc1 WAC – Isw2 catalytic subunit axis, leading to a ‘strained complex’. (C) The precise distance between the DNA-bound Isw2-recruitment factor and proximal nucleosome after nucleosome positioning by Isw2 is no longer a good substrate for Itc1 WAC interaction and further remodeling, so the Isw2 complex diffuses to new target loci.