Tokyo/Formulation/3.AHL-experssing model

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Revision as of 20:39, 26 October 2007

Works top　　0.Hybrid promoter　　1.Formulation　　2.Assay1　　3.Simulation　　4.Assay2　　5.Future works

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Step.3 Single cell model with hybrid promoter and cell-produced AHL

The differential equaitons of the system considering AHL produced by E.coli themselves were given as

Ex 3-1

Table 3

These equations were normalized as follows:

Ex 3-2

In the steady state,time derivatives are zero.As a result,the nullclines of this system were derived as

Ex 3-3

By substituting the third equation into the second,the nullclines for Ra and Rb were obtained as

Ex 3-4

Therefore, the phase plane of this system can be plotted as Fig.3.1.A-D and the number of equilibrium points were decided by the value of the parameters:

Figure 3.1.A

Figure 3.1.B

Figure 3.1.C

Figure 3.1.D

Comparison between Fig3.1.A and B indicated that Hill coefficients are critical parameters even in the cell-produced AHL model. In case of N2=1,N3=1 and λ=3, the phase plane was monostable. In contrast, in case of N2=2, N3=2 and λ=3, the phase plane was bistable.
In the cases of λ=1 (Fig.3.1.C and D), the system can not take bistability even if the values of Hill coefficients are changed. For the implementation of the circuit in a cell, parameter λ should be controlled by changing the RBS and/or promoter sequences of LuxR.

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