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. 2021 Mar 4;10:e64563. doi: 10.7554/eLife.64563

Figure 2. Characterization of HP1α-DNA condensate formation.

(A) Bright-field images of mixtures of HP1α and 147 bp DNA. (B) Heat map of the average radius of condensates for each condition in (A). (C) Average condensate radius for 1 μM 147 bp DNA plotted against HP1α concentration (cyan) or 100 μM HP1α plotted against 147 bp DNA concentration (magenta) and fit to a power law, error bars (obscured) represent the SEM. (D) Time stamped brightfield images of 100 μM HP1α and 147 bp, 2.7 kbp, or 9 kbp DNA depicting fusion and coalescence behavior. (E) Brightfield images of HP1α with either 30 nM 2.7 kb DNA (top) or 9 nM 9 kbp DNA (bottom). Throughout, purple boxes indicate presence of condensates.

Figure 2.

Figure 2—figure supplement 1. Exceedence probability of HP1α-DNA condensates.

Figure 2—figure supplement 1.

(A) Exceedance probability. The number of condensates (y-axis) with radius exceeding indicated size (x-axis) for each concentration of HP1α and DNA in Figure 2A. Expectation values determined by integrating each curve are reported in Figure 2B–C.
Figure 2—figure supplement 2. Characterization of HP1α condensates.

Figure 2—figure supplement 2.

(A) Ratio of HP1α dimer to estimated DNA-binding sites for experimental conditions in Figure 2A (~2 HP1α binding sites per 147 bp DNA oligo). (B) (top) Brightfield image of 100 μM HP1α and 1 μM 147 bp DNA and (bottom) output of automated condensate detection.( C) Bright-field images of HP1α dialyzed into low salt buffer (20 mM HEPES pH7.5, 40 mM KCl, and 1 mM DTT). (D) Normalized fluorescence anisotropy curves for each HP1 paralog. (E) Brightfield images of four HP1α concentrations mixed with 30 nM 2.7 kbp DNA in 20 mM HEPES pH7.5, 150 mM KCl, and 1 mM DTT.