IGEM:IMPERIAL/2009/toggle switch timer
mechanism: mutually repressive motif of the genetic toggle switch that acts as a predictable timer.
These timers exploit the finely balanced nature of a mutual inhibitory network, where changes in opposing repressor levels can disrupt bistability, and memory of induction can be lost as the system resets to its original default state.
For yeast timers, used LacI and TetR as the two mutually repressive gene products
To follow the expression state of the timers, placed yEGFP under the control of the LX promoter
Mathematically, this is due to a temporal lag in resetting caused by the network passing through a 'bottleneck' as it leaves bistability. This direct relationship allows timers with any reset time between 50 and 150 h to be chosen simply based on the strengths of the two promoters selected from the respective libraries