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Team:Tokyo Tech/Genetic toggle switch to implement rewritable function
From 2008.igem.org
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'''1. Writable function''' | '''1. Writable function''' | ||
| - | * Plac is induced under 30MPa pressure | + | * '''Plac''' is induced under 30MPa pressure |
| - | (It is known that Plac activity under 30MPa pressure is '''94.0''' times stronger than Plac activity under | + | (It is known that Plac activity under 30MPa pressure is '''94.0''' times stronger than Plac activity under atmospheric pressure) |
* Express CI and GFP | * Express CI and GFP | ||
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* CI represses PL and causes low LacI concentration | * CI represses PL and causes low LacI concentration | ||
| - | * Express increasingly CI and GFP ⇒ '''Bright!!''' | + | * Express increasingly CI and GFP('''inserted destruction tags''') ⇒ '''Bright!!''' |
'''2. Erasable function''' | '''2. Erasable function''' | ||
| - | * PL is induced by heat | + | * '''PL''' is induced by heat |
* Express LacI and LacI represses Plac | * Express LacI and LacI represses Plac | ||
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== Mathematical model == | == Mathematical model == | ||
| - | [[Image:Room_pressure_model.png|frame|right|fig5-2: | + | [[Image:Room_pressure_model.png|frame|right|fig5-2:Atmospheric pressure model]] |
[[Image:30MPa_pressure_model2.png|frame|right|fig5-3:30MPa pressure model]] | [[Image:30MPa_pressure_model2.png|frame|right|fig5-3:30MPa pressure model]] | ||
| - | We used two differential equation models and we call them ' | + | We used two differential equation models and we call them 'atmospheric pressure model' and '30MPa pressure model'. |
| - | The kinetics of the genetic toggle switch is calculated from ' | + | The kinetics of the genetic toggle switch is calculated from 'atmospheric pressure model' under atmospheric pressure while that is calculated from '30MPa pressure model' under 30MPa pressure. |
In order to implement rewritable function, we decided to use the difference of nullclines of each system so as to satisfy the following condition | In order to implement rewritable function, we decided to use the difference of nullclines of each system so as to satisfy the following condition | ||
* Converge to high CI concentration state under 30MPa pressure (writable) | * Converge to high CI concentration state under 30MPa pressure (writable) | ||
| - | * Bistable under | + | * Bistable under atmospheric pressure (erasable) |
Revision as of 19:20, 25 October 2008
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Genetic toggle switch to implement rewritable function
In order to implement rewritable function, we tried to construct Pressure Inducible Genetic Toggle Switch (in short PIGTS). We have to think two types of model - genetic circuit model and mathematical model - so as to construct PIGTS.
Genetic circuit model
1. Writable function
- Plac is induced under 30MPa pressure
(It is known that Plac activity under 30MPa pressure is 94.0 times stronger than Plac activity under atmospheric pressure)
- Express CI and GFP
- CI represses PL and causes low LacI concentration
- Express increasingly CI and GFP(inserted destruction tags) ⇒ Bright!!
2. Erasable function
- PL is induced by heat
- Express LacI and LacI represses Plac
- Therefore, GFP expression decreases
Mathematical model
We used two differential equation models and we call them 'atmospheric pressure model' and '30MPa pressure model'. The kinetics of the genetic toggle switch is calculated from 'atmospheric pressure model' under atmospheric pressure while that is calculated from '30MPa pressure model' under 30MPa pressure. In order to implement rewritable function, we decided to use the difference of nullclines of each system so as to satisfy the following condition
- Converge to high CI concentration state under 30MPa pressure (writable)
- Bistable under atmospheric pressure (erasable)
To implement rewritable function, we had to identify the domain of appropriate parameters.
Identify the domain of appropriate parameters
Two systems have six parameters. We have already known β30Plac = 94.0 and nPL = 3.0 from earlier studies, and we identified nPlac = 2.15 by our activity determination. And we can adjust promoter - RBS strength, so we had just consider the ratio of αPlac and αPL. Therefore, we can fix αPlac.
We identified β30PL = 1.42 by our experiment under 30MPa pressure. Therefore, we can implement rewritable function if we choose PL - RBS strength range from 2.4 to 7.4.
