Figure 1.

LANA_1–23 promotes chromatin self-association. (a) Self-association of wild-type nucleosomal arrays (WT-NA) is plotted as a function of the MgCl₂ concentration (shown in red). The same experiment done in the presence of a fivefold excess of LANA_1–23 or a triple alanine substitution of LANA_1–23 substituted at positions 8LRS10 (LRS) that abrogates binding to nucleosomes¹ is shown in blue and green, respectively. Each nucleosome has two charged surfaces and thus two binding sites for LANA_1–23. (b) Mg₅₀ values (obtained from experiments such as those shown in a) are plotted as a function of the molar ratio of nucleosomes in the array to LANA_1–23, assuming a saturation of 12. (c) Self-association of gh4 arrays (gh4-NA) is plotted as a function of the MgCl₂ concentration (shown in orange). Blue and green curves show gh4-NA in the presence of a fivefold molar excess of LANA_1–23 or LRS. Wild-type arrays are shown in red. (d) Mg₅₀ values are plotted as a function of the molar ratio of gh4 nucleosome to LANA_1–23. Error bars in all panels represent s.d. from three separate experiments.