Abstract
The malaria parasite, Plasmodiumfalciparum, proliferates rapidly in human erythrocytes by actively scavenging multiple carbon sources and essential nutrients from its host cell. However, a global overview of the metabolic capacity of intraerythrocytic stages is missing. Using multiplex 13C‐labelling coupled with untargeted mass spectrometry and unsupervised isotopologue grouping, we have generated a draft metabolome of P.falciparum and its host erythrocyte consisting of 911 and 577 metabolites, respectively, corresponding to 41% of metabolites and over 70% of the metabolic reaction predicted from the parasite genome. An additional 89 metabolites and 92 reactions were identified that were not predicted from genomic reconstructions, with the largest group being associated with metabolite damage‐repair systems. Validation of the draft metabolome revealed four previously uncharacterised enzymes which impact isoprenoid biosynthesis, lipid homeostasis and mitochondrial metabolism and are necessary for parasite development and proliferation. This study defines the metabolic fate of multiple carbon sources in P.falciparum, and highlights the activity of metabolite repair pathways in these rapidly growing parasite stages, opening new avenues for drug discovery.
Highlights
Considerable progress has been made in reducing the incidence of malaria over the last decade, the decline in malaria cases has stalled in recent years and resistance to frontline antimalarials is on the rise (WHO, 2019)
As an example of the workflow, polar LC-MS analysis of 13Cglucose labelled infected red blood cells (iRBCs) extracts revealed that 859 of the original 33,691 m/z features detected in unlabelled iRBCs exhibited decreased intensity following 13C-glucose labelling (Fig 1B), indicating that they likely correspond to mono-isotopic masses that decrease as metabolites become enriched for 13C atoms
We further investigated whether serine hydroxymethyltransferase (SHMT)-M might be in involved in generating one-carbon intermediates for cytoplasmic pathways by labelling iRBC with 2,3,3-D-serine and quantitating the amount of label exported into the cytosol for dTTP synthesis
Summary
Considerable progress has been made in reducing the incidence of malaria over the last decade, the decline in malaria cases has stalled in recent years and resistance to frontline antimalarials is on the rise (WHO, 2019). Considerable progress has been made in delineating key salvage and metabolic pathways involved in P. falciparum asexual development, which has formed the basis for genome-scale models of parasite metabolism (Fatumo et al, 2009; Plata et al, 2010; Bazzani et al, 2012; Tymoshenko et al, 2013). Despite these advances, > 40% of the protein-encoding genome remains unannotated and a significant fraction of annotated metabolic genes have yet to be assigned to specific metabolic pathways or reactions.
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