PgoITS is a constitutive promoter that ensures the production of golS protein. In the presence of gold ions, the golS binds with the gold ions to form a complex. This complex then induces PgoB (in other words stops the inhibition of PgolB), which transcribes the reporter gene, amilCP, to produce a blueish color.
In collaboration with the iGEM team Stonybrook we have worked on developing a model using Simbiology toolbox from Matlab.
Diagrammatically the model for gold sensing is represented in the figure 1
Governing Equations To Model The System
Parameters
Initial Conditions
Simulations
The figure above depicts the amount of AmilGFP (M) as a function of different gold concentration in the soil. We can see that with soil samples from around the mine we should expect approx 1M of protein and we should reach these quantities in approximately 3 days. We can see that with random soil samples we do not see an increase in the production of amiGFP.
Further work
We plan to develop the models for the other biosensing modules and then combine them to get a much comprehensive picture of what to expect when all three biosensors are being combined and deployed. We also plan to use these models to determine the experimental conditions that we need to use in the laboratory to characterize our biosensor
References
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[7] A. L. Lira, R. S. Ferreira, R. J. Torquato, H. Zhao, M. L. V. Oliva, S. A. Hassan and P. Schuck, "Binding kinetics of ultrasmall gold nanoparticles with proteins," National Library of Medicine: Nanoscale, vol. 10, no. 7, pp. 3235-3244, 15 February 2018.
[8] "PHYSICAL AND CHEMICAL NATURES OF POST ARTISANAL GOLD MINE AREA AT KEBUNLADO VILLAGE OF RIAU PROVINCE," Indonesia Mining Journal, vol. 23, no. 1, pp. 9-19, April 2020.