Figure 2
Schematic of positive-feedback amplifier. The basic design for the amplifier consists of GFP and LuxRΔ2-162 arranged in a bicistronic configuration under the control of the P luxI promoter. LuxRΔ2-162 functions in a positive feedback loop as it can bind to the P luxI promoter and activate its own transcription. In our design, LuxRΔ2-162 is also used as the input signal for the amplifier. LuxRΔ2-162, therefore, functions both as the input and positive feedback signal. GFP, the output signal, provides a measure of transcriptional activity.