(333b) Synthetic Circuits Design Using Proteon and Proteoff

Even though recent advances in synthetic biology have fueled our ability to build synthetic systems with user-defined function, the field still faces central challenges. One of the main challenges is the limited level of complexity underlying the newly designed synthetic systems; this complexity has recently reached a plateau [1]. Effectively addressing this limitation may necessitate the use of validated mathematical models that inform the design of synthetic systems with high complexity.

We have previously built and characterized two synthetic devices, proTeOn and proTeOff, that tightly control prokaryotic gene expression in a tetracycline-dependent fashion [2]. proTeOn (proTeOff)  upregulates the expression of a target gene in response to the presence (absence) of tetracycline. We are now using these devices to build synthetic circuits with various potential dynamics ranging from oscillations to bistability and switch-like behavior. These circuits integrate proTeOn and proTeOff along with molecular components from the lactose and tetracycline operon. We are currently designing these systems in silico using our experimentally validated models [2,3,4]. Mathematical modeling will then guide the in vivodesign and characterization of these systems.

These synthetic circuits will contribute towards designing systems with increased complexity which are robustly controlled and composed of well-studied molecular parts.

1) Purnick, P. E., & Weiss, R. (2009). The second wave of synthetic biology: from modules to systems. Nature Reviews Molecular Cell Biology, 10(6), 410-422.

2) Volzing, K., Biliouris, K., & Kaznessis, Y. N. (2011). ProTeOn and ProTeOff, new protein devices that inducibly activate bacterial gene expression. ACS Chemical Biology, 6(10), 1107-1116.

3) Biliouris, K., Daoutidis, P., & Kaznessis, Y. N. (2011). Stochastic simulations of the tetracycline operon. BMC systems biology, 5(1), 9.

4) Ramalingam, K. I., Tomshine, J. R., Maynard, J. A., & Kaznessis, Y. N. (2009). Forward engineering of synthetic bio-logical AND gates. Biochemical Engineering Journal, 47(1), 38-47.