Mfd is a widely conserved bacterial protein that couples DNA repair with transcription. Mfd recognizes RNA polymerase stalled at a non-coding template site of DNA damage, disrupts the transcription complex to release the transcript and enzyme, and recruits the DNA excision repair machinery to the site. The mechanism of RNA release has been illuminated by the discovery that Mfd causes forward translocation of RNA polymerase, using an ATP-dependent motor that is highly homologous to that of the Holliday branch migration protein RecG.