Analysis of the unique trypanothione metabolism in the framework of the Silicon Trypanosome project

LEROUX, ALEJANDRO E.; KRAUTH-SIEGEL, R. LUISE

Heidelberg

Congreso; Tropical Medicine and Parasitology - 25th Annual Meeting German Society for Parasitology; 2012

German Society for Parasitology

Trypanosoma brucei is the etiologic agent of human African trypanosomiasis, one of the most important neglected diseases in sub-Saharan Africa. Although sleeping sickness is fatal if untreated, the available drugs are far from satisfactory due to severe adverse effects as well as problems with efficacy, administration, and compliance. The Silicon Trypanosome project aims at the creation of a comprehensive, experiment-based, multi-scale mathematical model of trypanosome physiology. Its objective is to expand the established glycolysis model by including the pentose phosphate pathway and the unique trypanothione-based redox metabolism of the parasite which is already the target of several of the current chemotherapy drugs. As part of this collaborative project we will measure the kinetic constants of the parasite redox enzymes under pseudo-physiological conditions and determine the intracellular concentration and - where appropriate - the redox state of the proteins. For this purpose, we have defined and tested a buffer system that should mimic the cytosolic milieu of bloodstream T. brucei as much as possible. Fixed parameters are for instance an assay temperature of 37°C and a pH value of 7.0, reported for the cytosolic compartment of the parasite as well as the buffer composition. The kinetic characterization of trypanothione synthetase, one of the key enzymes of the trypanothione metabolism, revealed remarkable differences to the published data obtained under optimized but artificial conditions. These findings underline the importance of kinetic analyses under conditions that mimic as much as possible the intracellular milieu of the parasite. The experimental data produced will form the basis for the computational model of parasite biology, which should allow to predict how the cell reacts to a wide range of perturbations. We expect that, in the long run, the quantitative modelling enabled by the Silicon Trypanosome will play a key role in selecting molecular targets suited for the development of novel anti-parasitic drugs.