The main MG detoxification pathway in <i>Escherichia coli </i>consists of two enzymes, the glyoxalases I and II, and is dependent on glutathione (GSH). MG readily conjugates with GSH in a non-enzymatic manner. Two subsequent enzymatic reactions via the glyoxalases complete a cyclic process that recycles GSH and produces the non-toxic compound, D-lactate. An intermediate compound in the detoxification pathway, S-lactoylglutathione (SLG), activates potassium efflux systems KefB and KefC. This triggers a second mechanism of protection mediated by cytoplasmic acidification, enhancing chances of survival. Therefore, it is important to understand how cells regulate the concentration of this important intermediate compound. A deterministic model was proposed that describes the series of chemical reactions in the MG detoxification pathway, allowing one to predict the flux of all compounds produced during detoxification. Through an iterative process involving model formulation, parameter estimation, data fitting and validation against experimental data, different models were analysed and discriminated in this study. Mathematical simulations predicted that the glyoxalase pathway is not linear because it involves feedforward mechanisms for the control of SLG, the activator of the potassium efflux systems. The activities of the potassium efflux systems were investigated using deterministic models that describe the interactions between protein and ligand. From this model, it was possible to quantify the dependence of the possible binding states on the kinetic parameters of the system. Parameter estimation methods were used for the analysis of experimental data on the gating of the efflux systems, which proved useful for the design of new experimental strategies.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:521153 |
| Date | January 2009 |
| Creators | Almeida, Camila de |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=103942 |
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