Team:USTC Software/Transfer function of Part:BBa F2620


Part:BBa_F2620 had been fully characterized with data in partsregistry BBa_F2620 page. It is a composite biobrick with three individual biobricks: pTetR (R0040), LuxR(C0062) and lux pR. Without AHL, transcriptional level of lux pR is extremal low because of lack of activator, LuxR-AHL dimer. If we add AHL into the system within a very short time, expression of mature GFP is expected to increase significantly. To measure behaviors of the system consisting of BBa_F2620 using our software tool, we construct a system using plasmid pSB3C5 and Part:BBa_F2620 as well as a reporter gene:

USTCs luxr gfp assembly.PNG

where we use two consecutive terminators to indicate a complete termination. Time course simulation was performed to generate transfer function of stable GFP concentrations versus AHL concentration. It is of high consistence with experiment done by Haseloff Lab, MIT:

USTCs Transfer function.png

where GFP concentration is directly proportional to its synthetic rate. In our simulation, we add AHL of concentration ranging from 1E-10 to 1E-5 M (increasing by order of magnitude) to the reactor within one minute. Details of modeling are described here.

We also plot time and dose response measurements of GFP stable concentration following addition of AHL. We choose the same AHL concentrations as done in testing the transfer function and plot their dynamic curves of GFP:

USTC s dose response.PNG

A similar work to measure system response of luxr-plux to inducer AHL was done by USTC 2009 iGEM team. Besides measurement of dose response of GFP stable concentrations following addition of AHL, they construct four constitutive promoters, BBa_K176026, BBa_K176126, BBa_K176128, BBa_K176130, and quantitatively measured their effects to the response curves. The construction is modified by replacing pTet with the four promoters and pSB3C5 with high copy plasmid pSB1A3 (copy number: 200). Since there are no tetR protein existed in the system, we keep lux pR unchanged (it is equivalent to use pLux/Tet hybrid promoter).

The results is shown for each (we plot GFP concentration versus time and compare it with experiment measument):

  • Part:BBa_K176026 (Promoter Strength: 0.55 1/s)
USTCs Comp K176026.PNG
  • Part:BBa_K176126 (promoter strength: 0.0192 1/s)
USTCs Comp K176126.PNG
  • Part:BBa_K176128 (promoter strength: 0.0016 1/s)
Comp 176128.PNG
  • Part:BBa_K176130 (promoter strength: 6.4E-5 1/s)
Comp 176130.PNG