Transcription regulator that activates transcription by stimulating RNA polymerase (RNAP) recycling in case of stress conditions such as supercoiled DNA or high salt concentrations. Probably acts by releasing the RNAP, when it is trapped or immobilized on tightly supercoiled DNA. Does not activate transcription on linear DNA. Probably not involved in DNA repair. Interacts with the RNAP. Has a higher affinity for the core RNAP than for the holoenzyme. Its ATPase activity is stimulated by binding to RNAP. Belongs to the SNF2/RAD54 helicase family. RapA subfamily.