Kinetic flux profiling elucidates two independent acetyl-CoA biosynthetic pathways in Plasmodium falciparum
- Author(s)
- Cobbold, SA; Vaughan, AM; Lewis, IA; Painter, HJ; Camargo, N; Perlman, DH; Fishbaugher, M; Healer, J; Cowman, AF; Kappe, SHI; Llinas, M;
- Details
- Publication Year 2013-12,Volume 288,Issue #51,Page 36338-36350
- Journal Title
- Journal of Biological Chemistry
- Publication Type
- Journal Article
- Abstract
- Background: The acetyl-CoA biosynthetic pathways of the malaria parasite are unclear. Results: C-13-Labeling experiments in parasites lacking a functional pyruvate dehydrogenase (PDH) complex show that the PDH does not contribute significantly to the acetyl-CoA pool. Conclusion: The majority of acetyl-CoA biosynthesis in the parasite derives from a PDH-like enzyme and acetyl-CoA synthetase. Significance: The two routes for acetyl-CoA synthesis appear to have separate functions. The malaria parasite Plasmodium falciparum depends on glucose to meet its energy requirements during blood-stage development. Although glycolysis is one of the best understood pathways in the parasite, it is unclear if glucose metabolism appreciably contributes to the acetyl-CoA pools required for tricarboxylic acid metabolism (TCA) cycle and fatty acid biosynthesis. P. falciparum possesses a pyruvate dehydrogenase (PDH) complex that is localized to the apicoplast, a specialized quadruple membrane organelle, suggesting that separate acetyl-CoA pools are likely. Herein, we analyze PDH-deficient parasites using rapid stable-isotope labeling and show that PDH does not appreciably contribute to acetyl-CoA synthesis, tricarboxylic acid metabolism, or fatty acid synthesis in blood stage parasites. Rather, we find that acetyl-CoA demands are supplied through a PDH-like enzyme and provide evidence that the branched-chain keto acid dehydrogenase (BCKDH) complex is performing this function. We also show that acetyl-CoA synthetase can be a significant contributor to acetyl-CoA biosynthesis. Interestingly, the PDH-like pathway contributes glucose-derived acetyl-CoA to the TCA cycle in a stage-independent process, whereas anapleurotic carbon enters the TCA cycle via a stage-dependent phosphoenolpyruvate carboxylase/phosphoenolpyruvate carboxykinase process that decreases as the parasite matures. Although PDH-deficient parasites have no blood-stage growth defect, they are unable to progress beyond the oocyst phase of the parasite mosquito stage.
- Publisher
- ASBMB
- Research Division(s)
- Infection And Immunity
- Publisher's Version
- https://doi.org/10.1074/jbc.M113.503557
- Terms of Use/Rights Notice
- © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.
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Last Modified: 2015-05-25 03:02:31