Team:KULeuven/Model/Filter

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Pictogram filter.png

Contents

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Filter

Position in the system

The filter is positioned immediately after the input, because its job is to filter out possible noise signals or background signals that aren't caused by the "desease". It is the starting piece of the whole system, situated before the invertimer- and the reset-subsystem.

Describing the system

see also: Project:Filter

Filter BioBrick.jpg

ODE's

Parameters

Parameter values Filter
Name Value Comments Reference
Degradation rates
dpT7_tag 0.00155 s-1 UmuD tag added to speed up degradation of otherwise too stable T7 polymerase [http://www.openwetware.org/wiki/IGEM:Tsinghua/2007/Projects/RAP#Model_and_simulation link]
dmRNA_RIBOKEY 0.00462 s-1 [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=124983&blobtype=pdf link]
dclosed_mRNA_T7 0.00462 s-1 [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=124983&blobtype=pdf link]
dopen_mRNA_T7 0.00231 s-1 [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=124983&blobtype=pdf link]
dopen_mRNA_T7_complex 0.00231 s-1 [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=124983&blobtype=pdf link]
Equilibrium constants
Keq_1 0,015 [M] between closed and open T7 mRNA, experimental [http://parts2.mit.edu/wiki/index.php/Berkeley2006-RiboregulatorsMain link]
Keq_2 0.0212 [M] between closed T7 mRNA and key unlocked mRNA complex, experimental [http://parts2.mit.edu/wiki/index.php/Berkeley2006-RiboregulatorsMain link]
Rate constants
kdis 100 s-1 derived from experimental values
kcomplex 57 s-1 derived from experimental values
Transcription rates
TetR_var_transcr_rate p(TetR) dependent (RiboKey) between 5E-5 and 0.0125 s-1 ~ [aTc]
kmRNA_T7 0,0011 s-1

Remark: The key-lock system has been enhanced to 0.3%-14% (todo: new parameters will be added in a new overview)

Models

CellDesigner (SBML file)

filter

Matlab (SBML file)

Filter Matlab.jpg

Simulations

filter
Filter 1.PNG

1. AND gate of the filter

In the simulation we can clearly see this series of events:

  • when dark blue(ribokey) starts to increase, red (T7) also starts to increase, giving rise to an increasing amount of lactonase (blue) = AND-GATE.
  • when dark blue(ribokey) starts to decrease, red (T7) also starts to decrease, but much slower. The lactonase also starts to decrease, as it should be.

The short lifetime of the ribokey compared to the lifetime of the T7-protein, guarantees that the AND-GATE always works perfectly fine: when there's no more input, the ribokey will rapidly decrease (and disappear) and makes sure that the AND-GATE is not activated anymore, even when the T7-protein is slowly decreasing.

2. Filtering in practice

In the simulation three kinds of inputpulses have been used:

  • First pulse: 300s
    • small peak of lactonase
    • no influence on the timer
  • Second pulse: 1000s
    • medium peak of lactonase
    • influences the timer by levelling the timing capabilities, but it doesn't reset the timer
  • Third pulse: 5000s
    • huge peak of lactonase
    • reset of the timer: amount of complex goes to zero

Sensitivity Analysis

Sens Filter.png