Log-phase growth cells were crosslinked in 1% formaldehyde at a density of 5x105 cells per milliliter for 10 minutes at room temperature, then quenched with 125 mM glycine for 5 minutes, washed in PBS and snap frozen. Cells were then thawed and nuclei isolated by triton-X permeabilization followed by washing in a low detergent buffer. Then RIPA was added and sonication was performed by Branson (3 pulses of 30 seconds each with power output 4 W), followed by 14 cycles of sonication on the Bioruptor Pico. Chromatin extracts were then cleared by centrifugation and immunoprecipitation was performed with antibodies and protein A/G agarose beads overnight. The next day the beads were extensively washed with RIPA, then PBS, then resuspended in TE with 1% SDS and crosslinks were reversed overnight at 65 degrees Celcius. The next day RNase A treatment and proteinase K treatment were performed, followed by recovery of DNA with the Qiaquick spin columns. High throughput sequencing libraries were then constructed by A tailing, adapter ligation and 10-15 cycles of PCR followed by library purification, removal of PCR primer-dimers and high-throughput sequencing by HiSeq 4000.