Figure 6. H1 interactions with chromatin.

(a) H1 (yellow) prefers cruciform and nucleosomal DNA over linear DNA; a single linker DNA arm of ~18 base pairs is sufficient for high affinity binding. (b) NLE-Tri nucleosomes have three equivalent binding sites for asymmetric H1 interaction (boxed). H1 compacts trinucleosomes by rearranging linker DNA between nucleosomes, resulting in a 1:1 stoichiometry for NLE-trinucleosomes (middle panel); a second and third H1 molecule is precluded from binding. LE-trinucleosomes accommodate three H1 molecules. Our data suggests that only one linker histone contributes to each linker DNA stem.