After fixation, the cells were washed and sonicated using a Bioruptor (Diagenode) to generate chromatin extract. Chromatin extract was mixed with Drosophila virilis chromatin, cleared by centrifugation and used in ChIP with anti-Drosophila TFIIB antibody, pre-bound to a mix of Protein A and G Dynabeads. TFIIB bound DNA was purified, and libraries prepared with NEBNext Ultra II DNA Library Prep Kit for Illumina. Illumina sequencing was performed at SciLifeLab, Stockholm, Sweden.