Synthetic Genetic Devices for Decoding and Encoding Chemical Signals in Living Bacterial Cells

Forward engineering of synthetic gene circuits has made higher order information processing feasible to be performed in living cells. One of the next challenges in Synthetic biology is to create artificial decision-making signal processing system with more complex human-defined function and real world application. Here, we develop biological genetic circuits which are analogous to electronic 2-to-4 decoder and 4-to-2 priority binary encoder at the population level in living E. coli using synthetic logic gates, regulated by synthetic promoters containing binding sites for several transcription factors (TFs). We consider extracellular chemicals as inputs such as Isopropyl β-D-1thiogalactopyranoside (IPTG), anhydrotetracycline (aTc), n-acyl homoserine lactone (AHL) & arabinose and various fluorescent proteins as outputs. We have also used one mutated version of λ repressor CI: frame-shifted CI which we built and characterized in our lab. We have designed the component circuits based on the electronic decoder and encoder circuit conventions, constructed and characterized to get expected logic behaviors, studied their mathematically predictable properties and established agreement between their mathematical models and experimental outputs in terms of fluorescent protein expression.