Part:BBa_K173005
tetR logic inverter
This device takes PoPS as input and gives a PoPS output according to the transfer function of a logic inverter: tetR (BBa_C0040) is a repressor for tetR promoter (BBa_R0040), so high input signals give a low expression of tetR promoter and low input signals give a high expression of the promoter.
Measurement
Design
NOT logic gate is a common and useful part in logic gene circuit. This year, igem16-JNFLS-China team construct a device to identify the proper dosage of inducer to achieve a better inductive effect. In the device, we considered 5 strength constitutive promoters and used GFP to report the inductive effect (fig1). The induced degree is up to the response effect in a steady state and the speed of the effect depends on the dynamic process, these 2 points are very essential in logic gate. Therefore we test the dynamic process of different quantity of the repressor and different concentration of inducer. After that we did the steady-state analysis and the dynamic analysis. In the end we wish that it can be a reference method for the function of logic gate circuit for the future team to describe their elements' function.
Results
1 Response of the Not gate circuit to the inducer.
We measured the real-time dynamic response of every different circuit under their inducer (Fig.2). The fluorescent intensity increases significantly after the inducer is added, which suggests that the effect of the repressor is restrained by the inhibitor and the gene of GFP can be expressed.
2 The response dynamics is affected by repressor's concentration.
With differences of promoting strength, we figured out that there is a relationship between the concentration of the repressor and the response dynamics and it was showed in the length of response time (Fig.2). We ruled that the response time is the time required from when the steady state began to change to another steady state. The results showed a direct proportion. When the promoting strength is reducing, （1.0-0.47-0.24) The response time is decreasing. For example, when the promoting strength is 1.00, the concentration of tetracycline hychloride (TH) is 0.6μg/mL, the response time is more than 5 hours, when the promoting strength is 0.24, and concentration of TH is 0.1μg/mL, the response time declined to 2 hours.
3 The concentration of the repressor impacts the steady state.
When the concentration alters, the circuit changes in both initial state and the induced state (Fig. 2). The result showed an inversely proportion, which means the higher the concentration, the lower the quantity expressed.
4 How the concentration of inducer influences the steady state.
In order to observe the influence, we observed the alteration of fluorescent intensity at the 5th hour at different concentration of TH.(the promoting strength is 0.47, Fig. 3) The result is a curve in a "digital signal type" , which means that the repressor has the synergic effect.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
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