title: Reduced glycerol incorporation into phospholipids contributes to impaired intra-erythrocytic growth of glycerol kinase knockout Plasmodium falciparum parasites.
abstract: BACKGROUND
  Malaria is a devastating disease and Plasmodium falciparum is the most lethal parasite infecting humans. Understanding the biology of this parasite is vital in identifying potential novel drug targets. During every 48-hour intra-erythrocytic asexual replication cycle, a single parasite can produce up to 32 progeny. This extensive proliferation implies that parasites require substantial amounts of lipid precursors for membrane biogenesis. Glycerol kinase is a highly conserved enzyme that functions at the interface of lipid synthesis and carbohydrate metabolism. P. falciparum glycerol kinase catalyzes the ATP-dependent phosphorylation of glycerol to glycerol-3-phosphate, a major phospholipid precursor.
  
  
  METHODS
  The P. falciparum glycerol kinase gene was disrupted using double crossover homologous DNA recombination to generate a knockout parasite line. Southern hybridization and mRNA analysis were used to verify gene disruption. Parasite growth rates were monitored by flow cytometry. Radiolabelling studies were used to assess incorporation of glycerol into parasite phospholipids.
  
  
  RESULTS
  Disruption of the P. falciparum glycerol kinase gene produced viable parasites, but their growth was significantly reduced to 56.5±1.8% when compared to wild type parasites. (14)C-glycerol incorporation into the major phospholipids of the parasite membrane, phosphatidylcholine and phosphatidylethanolamine, was 48.4±10.8% and 53.1±5.7% relative to an equivalent number of wild type parasites.
  
  
  CONCLUSIONS
  P. falciparum glycerol kinase is required for optimal intra-erythrocytic asexual parasite development. Exogenous glycerol may be used as an alternative carbon source for P. falciparum phospholipid biogenesis, despite the lack of glycerol kinase to generate glycerol-3-phosphate.
  
  
  CONCLUSIONS
  These studies provide new insight into glycerolipid metabolism in P. falciparum.
authors: Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, Faculty of Heath Sciences, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, 7 York Road, Parktown, 2193, Johannesburg, South Africa. Electronic address: kubendran.naidoo@wits.ac.za.
authors: Kubendran
authors: K
authors: Naidoo
authors: Theresa L
authors: TL
authors: Coetzer
mesh_terms: D000818:Animals; D004912:Erythrocytes / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism*; D005991:Glycerol Kinase / Q000235:genetics / Q000378:metabolism*; D010271:Parasites / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010713:Phosphatidylcholines / Q000235:genetics / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000235:genetics / Q000378:metabolism; D010743:Phospholipids / Q000235:genetics / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010743:Phospholipids; D015800:Protozoan Proteins; D012333:RNA, Messenger; C483858:phosphatidylethanolamine; D005991:Glycerol Kinase; D005990:Glycerol
keywords: 3D7ΔEBA; 3D7ΔPfGK; AQP; EBA-175; G3P; Glycerol kinase; Knockout parasites; Malaria; P. falciparum glycerol kinase; PC; PE; PL; Pf; PfGK; Phospholipids; Plasmodium falciparum; aquaglyceroporin; erythrocyte binding antigen-175; erythrocyte binding antigen-175 knockout 3D7 P. falciparum parasites; glycerol kinase knockout 3D7 P. falciparum parasites; glycerol-3-phosphate; hDHFR; human dihydrofolate reductase; phosphatidylcholine; phosphatidylethanolamine; phospholipid