Team:ZJU-China/Modeling
From 2014.igem.org
1. The Whole Genetic Pathways
ODE equations:
Before recombination:
Formular.1 |
After combination, if combination succeeds.
Formular.2 |
Formular.3 |
After putting in Ara
Formular.4 |
Formulary:
Take GFP for example
Name | description |
---|---|
mgfp | The number of GFP mRNA |
pgfp | The number of GFP protein |
Npla | The number of plasmid |
αgfp | The maximal transcription rate of GFP |
α0gfp | The leak of the promoter |
αmgfp | The degradation rate of mRNA |
βmgfp | The translate rate of mRNA |
βpgfp | The degradation rate of GFP protein |
2. Recombination
description:
In this part, what we want to do is to find out the probability of the recombination of gene of interest through simple molecular dynamics simulation. Although this simulation is quite simple, it
certainly can tell us something right in some aspects within a certain accuracy.
The most important things for simulation are initial conditions and boundary conditions. Next, I will describe the initial conditions and boundary conditions in detail.Initial conditions:
What is initial condition? Simply, initial condition is the condition when your simulation starts. More simply, initial condition is that you know every molecular coordinate as well as velocity if needs.Boundary conditions:
What is boundary condition? E coli has a boundary, when the molecule runs out of its boundary, we should adjust it back in the E coli. In this simulation, periodic boundary condition is used.
Some basic biology facts and simulation parameter choice:
figure.1 E.coli cell |
- As shown above, the shape of E coli is similar to a cylinder. So in our simulation, we regard E coli as a cylinder whose radius is 0.5 micrometer, height is 2 micrometer.
- 2.By looking up some online information, we find the average velocity of protein in cells is about 10 , we estimate the average velocity of gene of interest fragment is the same order of magnitude of the protein for their mass is the same order of magnitude.
- 3.E coli replicate its chromosome in 40 minutes, the proceed rate of replication fork is about 10^5 bp/min. A fragment about 1kb needs 0.6s.
results |
3. Bistable Switch
ODE equtions:
Formular.5 |
Formular.6 |
Formulary:
Name | description |
---|---|
[ ] | [ ] stands for the concentration |
kc | Inversion rate constant |
kdi | dissociation equilibrium constant of int dimer-recombination site complex |
ki | dissociation equilibrium constant of int-int dimer |
kdix | dissociation equilibrium constant of int-xis dimer complex on a recombination site |
αset | The transcription rate of input set |
αreset | The transcription rate of input reset |
αI | The maximal transcription rate of int |
αX | The maximal transcription rate of xis |
γI | The degradation rate of int |
γX | The degradation rate of xis |
kd | The dissociation equilibrium constant |
figure.2The response to set input |
Reference
[1]Santos, C. N. S. & Yoshikuni, Y. Engineering complex biological systems in bacteria through recombinase-assisted genome engineering. Nature Protocols 9, 1320-1336, doi:10.1038/nprot.2014.084 (2014).
[2]Tyo, K.E., Ajikumar, P.K. & Stephanopoulos, G. Stabilized gene duplication enables long-term selection-free heterologous pathway expression. Nat. Biotechnol. 27, 760–765 (2009).
[3]Bentley, W.E. & Quiroga, O.E. Investigation of subpopulation heterogeneity and plasmid stability in recombinant Escherichia colivia a simple segregated model. Biotechnol. Bioeng. 42, 222–234 (1993).
[4]Paulsson, J. & Ehrenberg, M. Noise in a minimal regulatory network: plasmid copy number control. Q. Rev. Biophys. 34, 1–59 (2001).