Designing genetic circuits
At the turn of the millennium, James Collins and Stanislas Leibler embarked on similar projects independently: they designed the basic genetic circuits of synthetic biology they designed. And they came up with equally great approaches: they used E. coli to pair promoters with repressors that control each other’s behavior.
A toggle switch looks like a light switch. It can be in one of two states – on or off with the light switch – and requires a stimulus (such as a finger) to switch the system from one state to another. The genetic switch designed by James Collins and his colleagues consists of two pairs of promoters and repressors.
By default, the promoters engage in demonstrating their respective repeaters, but the two repeaters interact in a way that prevents both of them from expressing themselves at the same time.
The addition of stimuli, such as chemical stimulation of B. or a sudden temperature change, allows a transition from a stable state (R1 gene on, R2 gene off) to another stable state (R1 off, R2 off).
And when R1 is bound to a green fluorescent protein (GFP), states can be visualized by the presence or absence of a characteristic green glow.