Figure 1.

Schematic of the cell free gene expression circuits used in this study. (A): Sigma factor 70 (σ₇₀) induced expression of deGFP. (B): The circuit components encode for a negative feedback loop motif. Sigma factor 28 and deGFP-ssrA genes on the P70a promoters are expressed first because of the endogenous presence of sigma 70 factor in the extract. Sigma factor 28, once expressed, induces the P28a promoter, turning on the expression of the cI-ssrA gene which represses the P70a promoter. The circuit is modified from a previous study (Garamella et al., 2016) by including an ssrA degradation tag on the cI gene.