(277f) Bottom up Engineering of Synthetic Gene Networks

Synthetic gene networks can be constructed from bottom up with desired properties. However, constructing predictable gene networks with desired functions remains a challenge. It is because of the lack of well-characterized components and unpredictability of the assembled networks. The need for extensive, iterative characterization and retrofitting for optimization drastically slows down the construction of desired synthetic gene networks. Here we present a diversity-based approach that combines promoter library synthesis and mathematical modeling to quickly construct gene networks with desired properties (1). In this approach, promoters with random strength diversities are synthesized and characterized in parallel. When coupled with mathematical modeling to simulate the network at a whole system level, promoters that are optimal for the intended functions can be selected before the actual network assembly, without the need for post-hoc modifications. This approach will first be demonstrated in yeast by constructing negative feedforward loop networks. Then the method will be used to produce a synthetic gene network that acts as a timer, tunable by component choice. We utilize this network to control the timing of yeast flocculation phenotype, to illustrate a practical application of our approach. The construction of a synthetic cellular counter (2) will also be presented to lead to the discussion of future directions for library-modeling based approaches in synthetic biology.

1. Ellis, T.*, X. Wang*, and J. J. Collins. 2009. Diversity-based, model-guided construction of synthetic gene networks with predicted functions. Nature biotechnology 27:465-471.

2. Friedland, A. E.*, T. K. Lu*, X. Wang, D. Shi, G. Church, and J. J. Collins. 2009. Synthetic gene networks that count. Science 324:1199-1202.

(* equally contributed)