The protozoan parasite
Plasmodium falciparum is the causative agent of tropical malaria
and causes 1-3 million deaths annually worldwide. A balanced redox
milieu of the parasite and the human host cell is essential for
the successful invasion process and the replication of the parasite.
This is demonstrated, for example, by the protection of glucose-6-phosphate
dehydrogenase deficient erythrocytes as well as by the fact that
reduction equivalents in the form of thioredoxin and glutaredoxin
are required for the synthesis of deoxyribonucleotides.
Peroxiredoxins (Prx) are thiol-dependent peroxidases that are involved
in the detoxification of reactive oxygen species, as well as signal
transduction and differentiation processes. Man and P. falciparum
possess six and four different Prx, respectively, that can be subdivided
according to their localization, substrate specificity, and their
catalytic mechanism. Because P. falciparum neither has a catalase
nor a glutathione peroxidase it can be assumed that Prx are important
for the detoxification of peroxides in the malaria parasite. During
the last years we succeeded in generating and biochemically characterizing
four different P. falciparum Prx, a Prx from the closely related
parasite Toxoplasma gondii, and twelve further proteins of the thioredoxin-
and glutathione system from P. falciparum recombinantly.
Within the scope of this application, the catalytic mechanism and
the structure of the different P. falciparum Prx shall be characterized
comparatively using 3D molecular modelling, site directed mutagenesis,
protein biochemical studies, cryoelectron microscopy, crystallization,
and X-ray diffraction analysis. Furthermore, the physiological function
of the parasite and erythrocyte Prx shall be studied on the basis
of treated and untreated parasite cultures. Methodologically, stage
specific differential transcriptome and proteome analyses, knock-out
parasites, and pull down assays shall be applied. The aim of the
project is to functionally constitute the Prx system of the parasite-host
unit and to characterize its interaction with other redox systems.