title: Plasmodium falciparum glucose-6-phosphate dehydrogenase 6-phosphogluconolactonase is a potential drug target.
abstract: The malarial parasite Plasmodium falciparum is exposed to substantial redox challenges during its complex life cycle. In intraerythrocytic parasites, haemoglobin breakdown is a major source of reactive oxygen species. Deficiencies in human glucose-6-phosphate dehydrogenase, the initial enzyme in the pentose phosphate pathway (PPP), lead to a disturbed redox equilibrium in infected erythrocytes and partial protection against severe malaria. In P. falciparum, the first two reactions of the PPP are catalysed by the bifunctional enzyme glucose-6-phosphate dehydrogenase 6-phosphogluconolactonase (PfGluPho). This enzyme differs structurally from its human counterparts and represents a potential target for drugs. In the present study we used epitope tagging of endogenous PfGluPho to verify that the enzyme localises to the parasite cytosol. Furthermore, attempted double crossover disruption of the PfGluPho gene indicates that the enzyme is essential for the growth of blood stage parasites. As a further step towards targeting PfGluPho pharmacologically, ellagic acid was characterised as a potent PfGluPho inhibitor with an IC50 of 76 nM. Interestingly, pro-oxidative drugs or treatment of the parasites with H2O2 only slightly altered PfGluPho expression or activity under the conditions tested. Furthermore, metabolic profiling suggested that pro-oxidative drugs do not significantly perturb the abundance of PPP intermediates. These data indicate that PfGluPho is essential in asexual parasites, but that the oxidative arm of the PPP is not strongly regulated in response to oxidative challenge.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Australia.
authors.forename: Stacey M
authors.initials: SM
authors.lastname: Allen
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Australia.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Lim
authors.affiliation: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Jortzik
authors.affiliation: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Preuss
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Australia.
authors.forename: Hwa Huat
authors.initials: HH
authors.lastname: Chua
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Australia.
authors.forename: James I
authors.initials: JI
authors.lastname: MacRae
authors.affiliation: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rahlfs
authors.affiliation: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Haeussler
authors.affiliation: IBM Research - Australia, Carlton, Australia.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Downton
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Australia.
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: McConville
authors.affiliation: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Becker
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Melbourne, Australia.
authors.forename: Stuart A
authors.identifier: http://orcid.org/0000-0003-0114-7808
authors.initials: SA
authors.lastname: Ralph
mesh_terms: D000962:Antimalarials / Q000737:chemistry / Q000494:pharmacology*; D001769:Blood / Q000469:parasitology; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D004610:Ellagic Acid / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D055786:Gene Knockout Techniques; D005947:Glucose / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D062105:Molecular Docking Simulation; D058990:Molecular Targeted Therapy; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics
chemical_list: D000962:Antimalarials; D004791:Enzyme Inhibitors; D009097:Multienzyme Complexes; C560097:glucose-6-phosphate dehydrogenase-6-phosphogluconolactonase, Plasmodium falciparum; D004610:Ellagic Acid; D006861:Hydrogen Peroxide; D005954:Glucosephosphate Dehydrogenase; D002265:Carboxylic Ester Hydrolases; D005947:Glucose
keywords: 6-phosphogluconolactonase; Plasmodium; drug target; glucose-6-phosphate dehydrogenase; malaria; pentose phosphate pathway; redox