Ratiometric logic in living cells via competitive binding of synthetic transcription factors

Although there have been a flurry of designs in the recent past describing implementations of digital logic in living cells, computational elements that perform analog operations such as division and subtraction are scarce. By employing the principle of competitive binding between different DNA binding proteins, we present a novel approach towards ratiometric computation in living cells. After developing a quantitative model to analyze our design, we build and experimentally characterize our system in Saccharomyces cerevisiae. Our work demonstrates the feasibility of performing analog computation in eukaryotic cells and will potentially enable the design of more sophistated gene networks.