library_construction_protocol: Cells were fixed with 1% formaldehyde for 10 minutes. Samples were processed as described in Mumbach, et al., 2016, using DpnII (NEB, R05443) with the following modifications. 1) biotin incorporation was performed at 23°C for 4 hours with interval shaking (10 sec at 900 rpm, 5 min off). 2) Ligation was performed at 16°C for 4 hours with interval shaking (1 min at 500 rpm, 4 min off). 3) Samples were sheared using a Diagenode Biorupter with the following parameters: tube size = 1.5 mL, time on = 30 sec, time off = 30 sec, cycle # = 8. 4) A total of 3 µL of H3K27ac antibody (Abcam #ab4729) was added to the sample and incubated at 4°C overnight with rotation. 5) After ChIP washes, samples were resuspended in 20 µL removal of biotin-dATP master mix: 5 µL 10X NEB Buffer 2.1, 0.125 µL of dATP and dGTP at 10 mM each, 5 µL T4 DNA polymerase (NEB, M0203), and 39.8 µL distilled water. Samples were incubated at 20°C for 4 hours with interval shaking (1 min at 400 rpm, 4 min off). Lastly, size selection of libraries was performed using a two-sided selection with AMPureXP beads. Briefly, 22.5 µL of beads were added to the sample to capture fragments less than 700 bp. Supernatant was transferred to a new tube and 13.5 µL of beads were added to the supernatant sample to capture fragments greater than 300 bp. Libraries were eluted in 50 µL 10 mM Tris pH 8.0. Libraries were quantified using qPCR against Illumina primers and then paired end sequenced with read length of 75 bp to a sequencing depth of 200 million reads per sample over two Illumina NextSeq runs.