Photoregulation of the Transcription Reaction of T7 RNA Polymerase by Tethering an Azobenzene to the Promoter

At the flick of a switch: Photoregulation of the transcription reaction of T7 RNA polymerase was investigated by introduction of an azobenzene residue into the nontemplate strand of the T7 promoter. It was found that transcription was strongly impeded in the dark or by visible light irradiation, whereas it proceeded efficiently after UV irradiation. With this photoresponsive promoter, on–off switching of transcription by light irradiation was achieved (see figure).