Analog transistor models of bacterial genetic circuits

We show that compact analog current-mode circuits are effective at quantitatively modeling the behavior of genetic circuits. We present experimental biological data from genetic activator (PBAD) and repressor (PlacO) promoter circuits in E. coli. Simple subthreshold cascaded-differential-pair transistor circuits have input-output characteristics that quantitatively represent this data. Such foundational analog circuits can provide efficient conceptual, modeling, and simulation tools for the design and analysis of circuits in synthetic and systems biology.