The RNA polymerase II (Pol II) machinery generates DNA torsional stress, which, if not relieved by topoisomerase 1 (TOP1) through DNA swivelling, can impede transcription. Baranello et al. developed TOP1-seq to map the position of catalytically active TOP1 and found that it is enriched at sites of Pol II pausing, just downstream of transcription start sites. Pol II was found to interact through its carboxy-terminal domain (CTD) with TOP1 and stimulate its activity. CTD phosphorylation at Ser2 by BRD4 promotes Pol II pause–release and transcription elongation, and the authors found that it is also required for TOP1 stimulation. Thus, Pol II and TOP1 constitute a positive feedback loop where Pol II stimulates TOP1, which in turn facilitates Pol II pause–release and transcription elongation.