Divergent metabolism betweenTrypanosoma congolenseandTrypanosoma bruceiresults in differential drug sensitivity

Abstract

AbstractAnimal African Trypanosomiasis (AAT) is a debilitating livestock disease prevalent across sub-Saharan Africa, a main cause of which is the protozoan parasiteTrypanosoma congolense. In comparison to the well-studiedT. brucei, there is a major paucity of knowledge regarding the biology ofT. congolense. Here, we use a combination of omics technologies and novel genetic tools to characterise core metabolism inT. congolensemammalian-infective bloodstream-form parasites, and test whether metabolic differences compared toT. bruceiimpact upon drug sensitivity. LikeT. brucei, glycolysis plays a major part inT. congolenseenergy metabolism. However, the rate of glucose uptake is significantly reduced inT. congolense, with cells remaining viable when cultured in concentrations as low as 2 mM. Instead of pyruvate, the primary glycolytic endpoints are succinate, malate and acetate. Comparative transcriptomics analysis showed higher levels of activity associated with the mitochondrial pyruvate dehydrogenase complex, acetate generation and the succinate shunt inT. congolense. However, based on omics analysis and chemical inhibition, there does not appear to be significant levels of oxidative phosphorylation. Stable-isotope labelling of glucose enabled the comparison of carbon usage betweenT. bruceiandT. congolense, highlighting differences in nucleotide and fatty acid metabolism. To validate the metabolic similarities and differences, both species were treated with pharmacological inhibitors, confirming a lack of essential electron transport chain activity inT. congolense,but increased sensitivity to inhibition of mitochondrial pyruvate import. Strikingly,T. congolenseexhibited significant resistance to inhibitors of fatty acid synthesis, including a 780-fold greater EC50against the lipase and fatty acid synthase inhibitor Orlistat, compared toT. brucei. These data highlight that bloodstream formT. congolensediverges fromT. bruceiin key areas of metabolism, with several features that are intermediate between bloodstream- and insect-stageT. brucei. These results have implications for drug development, mechanisms of drug resistance and host-pathogen interactions.