Design of light-switchable phage promoter for efficient photo-regulation of gene-expression.

Efficient photoregulation of transcription by T7 RNA polymerase (RNAP) has been achieved with modified T7-promoter involving two azobenzene moieties at RNAP recognition region and TATA region simultaneously. Transcription proceeded 7.5-fold faster after UV irradiation than that under dark condition. Kinetic parameters (kcat, Km) for the transcription revealed that an azobenzene at each position played a different role and thus synergistic effect of photo-regulation was achieved with the promoter involving two azobenzenes.