1. Construction of a Genetic Toggle Switch in Escherichia coli
All diagrams except the for the detailed switch diagram taken from:
Gardner, T.S., Cantor, C.R. and Collins, J.J. (2000)Construction of a Genetic Toggle Switch in Escherichia coli Nature 403 (6767)

2. Design U = concentration repressor 1 V = concentration repressor 2
α = effective rates of synthesis
β and γ = cooperativity of repressors

3. Detail

4. Specifications In absence of inducer, only one promoter
should be effectively
active
Addition of inducer (eg.
IPTG or thermal pulse)
should trigger switching
to desired state

5. Product 3 Promoter systems: Low State: PLs1con (CI) (Stronger)
PLtetO-1 (TetR) v u
High State:
Ptrc-2 (LacI)

6. Characteristics η = cooperativity of IPTG binding
K = dissociation constant

7. Pros Cons . Is completely stable in both states
Can be switched between states easily
Small construct so products can be placed downstream
Requires protein degradation so takes a LONG time to switch between states
IPTG cannot be removed from environment after induction