Team:USTC Software/Repressilator



The repressilator is a synthetic genetic regulatory network designed to exhibit a stable oscillation shown via expression of GFP (green fluorescent protein). The work is reported by Michael B. Elowitz and Stanislas Leibler in their work at 2000. They constructed a system of three genes connected in a cyclical negative feedback loop so that gene A represses gene B, which represses gene C, which represses gene A. The implementation of this idea used a low copy plasmid encoding the repressilator, and the higher copy reporter, which were used to transform a culture of Escherichia coli.

Parts assembling: the top assembling is the construction used in our software and the bottom one is the toggle switch design in their work.

We construct a model to stimulate the behavior of repressilator, the results are showed as following:

USTCS repressilator.JPG

The meanings of the legend used in the figure are demonstrated as follows: [14 (lacI153)4] refers to the binding product of four lacI protein molecules, [12 (CIlam154)2] refers to the binding product of two CIlam protein molecules, while [10 (tetR154)2] refers to the binding product of two tetR protein molecules. The system exhibits oscillation behavior after initial time of 86000, the concentration of (lacI)4, (CIlam)2 and (tetR)2 changes periodically as the function of time. To be specific, the concentration of (tetR)2 increase when the concentration of (lacI)4 declines due to the remove of repression. And the concentration reaches the peak level when the concentration of (LacI)4 reaches its lowest level. Then the concentration of (tetR)2 decreases while the concentration of (CIlam)2 begins to arise because the repression from (tetR)2 is gradually relieved. Noted that the concentration peak level of (CIlam)2 and (tetR)2 are nearly more than twice the max concentration of (lacI)4, this may attribute to the difference of binding tendency between (CIlam)2, (tetR)2 and (lacI)4. The internal binding strength of (tetR)2 dimer and (CIlam)2 dimer are stronger than that of (lacI)4 tetramer. more details