Figure 3.

(a) The distance between the DNA ends for mononucleosomes in the closed conformation, d₁, under different divalent cationic conditions. (b) The distance between the DNA ends for mononucleosomes in the open conformation, d₂. (c) The fraction of nucleosomes in the closed conformation, f₁. (d) The apparent equilibrium constant, K_apparent, characterizing the DNA breathing motion under different MgCl₂ concentrations. The legend is the same for all four graphs. A t-test is applied to compare the statistical significance of the measurements in (a–c) for the four mononucleosomes. Each data point that is statistically different than WT is labeled based on the confidence level. The confidence levels are (^∗) for 99% (p = .01) and (+) for 95% (p = .05). Unlabeled data points in (a–c) are not statistically different than WT at the 95% confidence level. f₁ is the only parameter used to calculate K_apparent therefore the statistical significance is the same in (d) as it is in (c). Error bars are omitted from these graphs to avoid overcrowding. Graphs that include the error bars are available in Figs. S13, S15, and S17.