Extended Data Fig. 8: Nucleosome disorganization and chromatin phase separation are specifically driven by Swi6.

a, Schematic of chromatin self-association assay. b, c, Restraining octamer dynamics do not affect the condensation of unmethylated chromatin in liquid droplets. Self-association assays in b are performed with unmethylated nucleosome arrays containing H3•H4 S-S (oxidized) and H3•H4 S-H (reduced) octamers as a function of increasing concentration of Swi6. In c, bright-field representative images of the array–Swi6 complex analysed in b show that the formation of phase-separated droplets is not affected by the disulfide linkages in absence of H3K9me3. d, Swi6 induces chromatin condensation in liquid droplets at physiological conditions—150 mM KCl, 30 °C, 2 μM Swi6. Bright-field representative images. e, Swi6 alone does not form phase-separated liquid droplets. Bright-field representative images of the Swi6 alone. f, Left, self-association assay performed with naked DNA (601 × 12, approximately 2 kb) in presence of increasing concentrations of Swi6. Right:,bright-field representative images of the DNA–Swi6 complex analysed in the left panel, showing the formation of phase-separated droplets. g, Zmet2 does not form phase-separated assemblies alone and it does not promote chromatin condensation in liquid droplets. Experiments are done at 40 nM nucleosome arrays, with 2 and 5 μM of Zmet2. Bright-field images of buffer only and Swi6–chromatin droplets are shown as controls. h, Titration of the denaturant guanidinium-HCl into nucleosome arrays does not promote formation of phase-separated droplets, which indicates that Swi6 specifically disorganizes the nucleosome core. i, Disulfide cross-links between H3 and H4 impair Mg²⁺-driven self-association of nucleosome arrays, indicating the role of nucleosome core dynamic for inter-nucleosome interactions. j, Left, Mg²⁺-driven self-association of unmethylated and H3K9cme3 arrays are comparable. Right, representative bright-field images of the H3K9cme3 array sedimentation analysed in the left panel, showing the formation of rounded phase-separated condensates at 2 and 3 mM Mg²⁺. The assay is performed in TE 0.1 (10 mM Tris pH 7.8, 0.1 mM EDTA) and 75 mM KCl. k, Nucleosome arrays quality controls, showing comparable octamer saturation and absence of over- and under-assemblies. Arrays are digested with HpaI, run on a native acrylamide gel, and DNA is stained. For source gel data, see Supplementary Fig. 1. All arrays used in this study conformed to the quality standard shown in k. In b–i and j, measurements and images entailed three independent experiments; error bars reflect s.d.