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

Figure 6. The disordered extensions of HP1α regulate DNA compaction and condensate formation.

(A and B) Bright-field images of HP1α domain mutants and DNA. (A) Titration of HP1α domain mutants with 500 nM 147 bp DNA. (B) Titration of HP1α domain mutants with 9 nM 9 kbp DNA. Purple boxes indicate presence of condensates. (C) Kymograms of DNA compaction by HP1α domain mutants. DNA is labeled with dCas9 (top) and YOYO-1 (middle), also shown as composite image (bottom). Data shown for reactions including 50 μM HP1αΔNTE, 5 μM HP1αΔCTE, and 5 μM HP1αΔNTEΔCTE, respectively. Arrowheads represent estimated time of protein injection. (B-) or (-) specifies location of the barrier. (D) Average DNA compaction by 5 μM HP1α (N = 157), 5 μM HP1αΔCTE (N = 96), and 5 μM HP1αΔCTEΔNTE (N = 89). (E) Average DNA compaction by 50 μM HP1α (N = 272) and 50 μM HP1αΔNTE (N = 163). In (D) and (E) error bars represent standard deviations.

Figure 6.

Figure 6—figure supplement 1. Proposed model of HP1α autoregulation and potential oligomerization.

Figure 6—figure supplement 1.

(A) Proposed model of HP1α autoregulation and potential oligomerization.
Figure 6—figure supplement 2. DNA compaction activity of HP1α domain mutants.

Figure 6—figure supplement 2.

(A) Cartoon of HP1α extension mutants with color-coded disordered residues: positive residues (K and R) blue, negative residues (E and D) red, proline yellow, and all other residues grey. (B) Timestamped images of DNA labeled with YOYO-1 undergoing compaction by 5 μM HP1αΔCTE, 5 μM HP1αΔNTEΔCTE, and 50 μM HP1αΔNTE (unlabeled) shown before, during, and after compaction. (B-) or (-) specifies location of the barrier. (C) Average DNA compaction by each HP1α mutant, HP1αΔCTE (N = 96), HP1αΔCTEΔNTE (N = 89), and HP1αΔNTE (N = 163). Error bars represent standard deviations. Compaction velocity estimated from linear fit to data (cyan). Fit constrained to the region within the two red lines.