Investigation of a sulphur mobilisation gene in Plasmodium falciparum.

Plasmodium falciparum is the principal causative agent of malaria. Cells of the organism harbour a plastid organelle that constitutes a potential drug target. Metabolic functions associated with the plastid include the synthesis of isoprenoids, fatty acids and haem. Iron-sulphur Fe-Sl clusters may also be assembled in the organelle. Two systems (ISC and SUF) are implicated in biological Fe-S cluster assembly in malaria. The ISC system probably functions in the mitochondrion while the SUF system operates in the plastid. The objective of this project was to investigate a gene in P. falciparum with marked homology to SufS, a cysteine desulphurase (EC 2.8.1.7) of the SUF system in Escherichia coli and Arabidopsis thaliana. P. falciparum SufS (PfSufS) is encoded on chromosome seven of the nuclear genome but is predicted to be trafficked to the plastid organelle. A number of techniques have been applied to investigate the function of PfSufS in this thesis. Following a general introduction in chapter 1, subsequent chapters describe progress with this work. In chapter 2, account is given of investigations into the properties of PfSufS using a combination of bioinformatic and in vitro techniques. Progress towards defining the intracellular targeting of PfSufS by transfection and immunolocalisation is described in chapter 3. Development of a simple colorimetric cysteine desulphurase assay is reported in chapter 4. Finally, attempts have been made to produce recombinant PfSufS for enzymological studies (chapter 5)