Figure 1

Schematic of the RNAi-based OFF control device architecture. A catalytic ribozyme switch is placed upstream of a pri-miRNA in the same expression cassette. (a) In the absence of the input ligand, the ribozyme switch cleaves once it is transcribed, aborting transcription such that the miRNA is not be transcribed, thereby resulting in high target gene expression levels. (b) In the presence of ligand, ribozyme cleavage is inhibited such that transcription proceeds through the pri-miRNA, which undergoes proper miRNA biogenesis. Target expression levels are lowered due to miRNA silencing.