Design principles of transcriptional logic circuits

Using a set of genetic logic gates (AND, OR and XOR), we constructed a binary full-adder. The optimality analysis of the full-adder showed that, based on the position of the regulation threshold, the system displays different optimal configurations for speed and accuracy under fixed metabolic cost. In addition, the analysis identified an optimal trade-off curve bounded by these two optimal configurations. Any configuration outside this optimal trade-off curve is sub-optimal in both speed and accuracy. This type of analysis represents a useful tool for synthetic biologists to engineer faster, more accurate and cheaper genes.