Dataset Information

Gluconeogenesis using glycerol as a substrate in bloodstream-form Trypanosoma brucei

ABSTRACT: Bloodstream form African trypanosomes are thought to rely exclusively upon glycolysis, using glucose as a substrate, for ATP production. Indeed, the pathway has long been considered a potential therapeutic target to tackle the devastating and neglected tropical diseases caused by these parasites. However, plasma membrane glucose and glycerol transporters are both expressed by trypanosomes and these parasites can infiltrate tissues that contain glycerol. Here, we show that bloodstream form trypanosomes can use glycerol for gluconeogenesis and for ATP production, particularly when deprived of glucose following hexose transporter depletion. We demonstrate that Trypanosoma brucei hexose transporters 1 and 2 (THT1 and THT2) are localized to the plasma membrane and that knockdown of THT1 expression leads to a growth defect that is more severe when THT2 is also knocked down. These data are consistent with THT1 and THT2 being the primary routes of glucose supply for the production of ATP by glycolysis. However, supplementation of the growth medium with glycerol substantially rescued the growth defect caused by THT1 and THT2 knockdown. Metabolomic analyses with heavy-isotope labelled glycerol demonstrated that trypanosomes take up glycerol and use it to synthesize intermediates of gluconeogenesis, including fructose 1,6-bisphosphate and hexose 6-phosphates, which feed the pentose phosphate pathway and variant surface glycoprotein biosynthesis. We used Cas9-mediated gene knockout to demonstrate a gluconeogenesis-specific, but fructose-1,6-bisphosphatase (Tb927.9.8720)-independent activity, converting fructose 1,6-bisphosphate into fructose 6-phosphate. In addition, we observed increased flux through the tricarboxylic acid cycle and the succinate shunt. Thus, contrary to prior thinking, gluconeogenesis can operate in bloodstream form T. brucei. This pathway, using glycerol as a physiological substrate, may be required in mammalian host tissues.

INSTRUMENT(S): Liquid Chromatography MS - Alternating (LC-MS (Alternating))

SUBMITTER: Julie Kovarova

PROVIDER: MTBLS706 | MetaboLights | 2018-12-10

REPOSITORIES: MetaboLights

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Publications

Gluconeogenesis using glycerol as a substrate in bloodstream-form Trypanosoma brucei.

Kovářová Julie J Nagar Rupa R Faria Joana J Ferguson Michael A J MAJ Barrett Michael P MP Horn David D

PLoS pathogens 20181227 12

Bloodstream form African trypanosomes are thought to rely exclusively upon glycolysis, using glucose as a substrate, for ATP production. Indeed, the pathway has long been considered a potential therapeutic target to tackle the devastating and neglected tropical diseases caused by these parasites. However, plasma membrane glucose and glycerol transporters are both expressed by trypanosomes and these parasites can infiltrate tissues that contain glycerol. Here, we show that bloodstream form trypan ...[more]

PMID: 30589893

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Project description:The bloodstream forms of Trypanosoma brucei (BSF), responsible for the sleeping sickness, primarily evaluate in the blood of its mammalian hosts. The skin and the adipose tissues were recently identified as additional major sites for the parasite proliferation and transmission through its insect vector blood ingestion. Glucose is the only carbon source used by the blood parasites to feed its central metabolism, however, the metabolic behavior of the tissue-adapted parasites has not yet been addressed. Since production of glycerol is an important primary function of adipocytes, we have adapted the BSF trypanosomes to glucose-depleted and glycerol-rich growth medium (CMM_Gly/GlcNAc) and compared its metabolism and proteome with standard glucose-rich growth conditions (CMM_Glu). BSF consume 2-times more oxygen per carbon consumed in CMM_Gly/GlcNAc and is 11.5-times more sensitive to SHAM, a specific inhibitor of the alternative oxidase, which is consistent with the expected absolute requirement of the mitochondrial respiratory chain activity to convert glycerol into dihydroxyacetone phosphate. Metabolomic analyses by mass spectrometry showed that 13C-labeled glycerol is incorporated into hexose phosphates through gluconeogenesis. After several weeks of growth in CMM_Gly/GlcNAc, BSF adapt their metabolism by increasing and decreasing the rate of glycerol and glucose consumption, respectively. As expected RNAi-mediated down-regulation of glycerol kinase expression abolished glycerol degradation and is lethal for BSF growth in CMM_Gly/GlcNAc. However, the glycerol kinase activity is 7.8-fold decreased in CMM_Gly/GlcNAc, as confirms by western blotting and proteomic analyses, which suggests that the huge excess of glycerol kinase, which is not necessary for glycerol metabolism, is required for another yet undetermined non-essential function in glucose rich-conditions. Altogether these data shows that BSF trypanosomes are well adapted to glycerol-rich conditions, which could be encountered by the parasite in extravascular niches, such as skin and adipose tissues.

Dataset Information

Gluconeogenesis using glycerol as a substrate in bloodstream-form Trypanosoma brucei

Publications

Gluconeogenesis using glycerol as a substrate in bloodstream-form Trypanosoma brucei.

Similar Datasets

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