Construction and validation of a detailed kinetic model ofglycolysis in asexual Plasmodium falciparum : a feasibilitystudy

[摘要] ENGLISH ABSTRACT:In Africa alone, Plasmodium, the causative agent of malaria is estimated to killa child, under the age of five every thirty seconds140. The ability of the parasiteto rapidly attain resistance, has resulted in immunity of the parasite to all,except one group of frontline drugs. The need to develop novel drugs, vaccinesand prevention strategies that are accessible and affordable for third worldcountries is of the utmost importance to prevent needless human suffering anddeath.The glycolytic pathway is an attractive drug target since it is the principalsource of ATP for the parasite. Many of the glycolytic enzymes have beenstudied and proposed as drug targets, but the importance of these enzymesfor the function of the pathway as a whole has not been considered. It isknown, from the frameworks of metabolic control analysis, that control of theflux and metabolite concentration can be divided among the individual steps. Differential control analysis of Plasmodium and erythrocyte glycolysis mayreveal potential drug targets. These analyses require a detailed kinetic modelof Plasmodium glycolysis, and the feasibility of constructing and validatingsuch a model was the aim of this study.In this work we determined the feasibility of constructing and validating adetailed kinetic model for the Plasmodium falciparum glycolytic pathway.Whether the construction and validation of this kinetic model was feasibleor not was decided on the basis of the ability to: i) culture and isolatesufficient asexual parasites for enzymatic and steady state assays , ii) obtainkinetic parameters such as Km and Vmax for each glycolytic enzyme, eitherfrom literature or experimentally, iii) measure glycolytic fluxes, iv) determineglycolytic intermediate concentrations, v) construct a kinetic model from thekinetic parameters and vi) validate it with steady state glycolytic fluxes andmetabolite concentrationsEach of the above criteria were successfully addressed. In summary, thekinetic parameters and glycolytic fluxes that were measured experimentally,were used to construct and partially validate a detailed kinetic model,respectively. Further validation of the model by means of steady statemetabolite concentrations was shown to be possible with the development ofa suitable protocol to measure the glycolytic intermediate concentrations.The model presented in this work may play an important role in drugtarget identification and improving the current understanding of host-parasiteinteractions and glycolytic regulation.

[发布机构] Stellenbosch University