title: Dissecting the role of glutathione biosynthesis in Plasmodium falciparum.
abstract: Glutathione (γ-glutamylcysteinyl-glycine, GSH) has vital functions as thiol redox buffer and cofactor of antioxidant and detoxification enzymes. Plasmodium falciparum possesses a functional GSH biosynthesis pathway and contains mM concentrations of the tripeptide. It was impossible to delete in P. falciparum the genes encoding γ-glutamylcysteine synthetase (γGCS) or glutathione synthetase (GS), the two enzymes synthesizing GSH, although both gene loci were not refractory to recombination. Our data show that the parasites cannot compensate for the loss of GSH biosynthesis via GSH uptake. This suggests an important if not essential function of GSH biosynthesis pathway for the parasites. Treatment with the irreversible inhibitor of γGCS L-buthionine sulfoximine (BSO) reduced intracellular GSH levels in P. falciparum and was lethal for their intra-erythrocytic development, corroborating the suggestion that GSH biosynthesis is important for parasite survival. Episomal expression of γgcs in P. falciparum increased tolerance to BSO attributable to increased levels of γGCS. Concomitantly expression of glutathione reductase was reduced leading to an increased GSH efflux. Together these data indicate that GSH levels are tightly regulated by a functional GSH biosynthesis and the reduction of GSSG.
authors.affiliation: Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK. Eva-Maria.Patzewitz@nottingham.ac.uk
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Patzewitz
authors.forename: Eleanor H
authors.initials: EH
authors.lastname: Wong
authors.forename: Sylke
authors.initials: S
authors.lastname: Müller
mesh_terms: D001692:Biological Transport; D053898:Biosynthetic Pathways / Q000235:genetics*; D019328:Buthionine Sulfoximine / Q000633:toxicity; D002470:Cell Survival / Q000187:drug effects; D017353:Gene Deletion; D020043:Genes, Essential; D005978:Glutathione / Q000096:biosynthesis*; D010963:Plasmodium falciparum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*
chemical_list: D019328:Buthionine Sulfoximine; D005978:Glutathione