Scheme 2
From: Artificial complementary chromatic acclimation gene expression system in Escherichia coli
An artificial CCA system with green and red light-regulated dual gene expression system by employing a single photosensor, CcaS/CcaR, combined with G-box inserted upstream of promoters. a Under green light illumination, CcaS, a green light sensor, activates the response regulator CcaR. Activated CcaR binds to the G-boxes, and upregulates the cpcG2 promoter, consequently, the rfp gene is transcribed. Simultaneously, CcaR binds to the G-box located between PtrcΔLacO and reporter gene, bfp, and downregulates the transcription of bfp. b Under red light illumination, CcaS inactivates and dephosphorylates CcaR. Inactivated CcaR is no longer able to bind to the G-boxes, and downregulates the cpcG2 promoter; consequently, the rfp gene is not transcribed. Simultaneously, CcaR does not bind to the G-box located between PtrcΔLacO and reporter gene, bfp, transcription under the PtrcΔLacO promoter is upregulated, and the bfp gene is transcribed