Chromatin extraction and ChIP were performed as described in Kloet, S. L. et al. (doi:10.1038/nsmb.3248 ) Five ng/sample of ChIP were prepared for sequencing with the Kapa Hyper-prep Kit (Kapa Biosystems) using NEXTflex adapters (Bio Scientific) and amplified with ten cycles of PCR. Libraries were size-selected to obtain 300bp fragments using E-gel (Invitrogen) and sequenced on an Illumina NextSeq machine to obtain 75bp reads