Team:SydneyUni Australia/Modelling Conclusion

From 2013.igem.org

Conclusions:

• In our model we find that 1mM of DCA is removed from solution within roughly 50 minutes when the DCA degrading cells are at a concentration of 2E8 cells/mL (graph 1 and graph 5).

• It is also evident that bacterial growth can occur (graph 4, graph 8 and graph 9). This growth is due to the degradation of DCA to glycolate. By comparing graph 6 and graph 9, one can see that bacterial growth correlates with glycolate accumulation.

The cytotoxic metabolic intermediate chloroactealdehyde doesn't accumulate to a significant concentration in any of the pathways and is consistently at a negligibly small concentration. From Graphs 3 and 7 one can see that chloroacetaldehyde reaches a maximum concentration of roughly 0.2 mM in both pathways. Chloroacetaldehyde is seen to be metabolised very quickly; this concentration maximum is very short lived where it peaks at roughly 0.03 seconds and returns back to 0 mM by 0.5 seconds. It is expected that chloroacetaldehyde toxicity will not be a problem in our engineered cells.

It is also possible to conclude that the pathways remove DCA at the same rate (through comparing graphs 1 and 5).

References:

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[2] Janecki, D. J., Bemis, K. G., Tegeler, T. J., Sanghani, P. C., Zhai, L., Hurley, T. D., Bosron, W. F. & Wang, M. (2007). A multiple reaction monitoring method for absolute quantification of the human liver alcohol dehydrogenase ADH1C1 isoenzyme. Analytical Biochemistry, 369(1), 18-26.

[3] Pandey, A. V. & Flück, C. E. (2013). NADPH P450 oxidoreductase: Structure, function, and pathology of diseases. Pharmacology & Therapeutics, 138(2), 229-254.

[4] van der Ploeg, J., Shmidt, M. P., Landa, A. S., & Janssen, D. B. (1994). Identification of Chloroacetaldehyde Dehydrogenase Involved in 1,2-Dichloroethane Degradation. Applied Environmental Microbiology 60(5), 1599-1605.

[5] van der Ploeg, J., van Hall, G. & Janssen, D. B. (1991) Characterization of the haloacid dehalogenase from Xanthobacter autotrophicus GJ10 and sequencing of the dhlB gene. Journal of Bacteriology, 173(24), 7925-33.

[6] Sinensky, M. I. (1974). Homeoviscous Adaption – A Homeostatic Process that Regulates the Viscosity of Membrane Lipids in Escherichia coli. Proceedings from the National Academy of Science of the United States of America, 71(2), 522-525.

[7] CyberCell Database

[8]

[9]

[10] http://www.dtsc.ca.gov/AssessingRisk/Upload/12dca.pdf

[11] Ishihama, Y., Schmidt, T., Rappsilber, J., Mann, M., Hartl, F. U., Kerner, M. J. & Frishman, D. (2008) Protein abundance profiling of the Escherichia coli cytosol. BMC Genomics, 9:102.

[12] Lord, J. M. (1972) Glycolate oxidoreductase in Escherichia coli. Biochemica et Biophysica Acta 267:2, 227-327.