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

Kovářová, J., Nagar, R., Faria, J., Ferguson, M. A.J., Barrett, M. P. and Horn, D. (2018) Gluconeogenesis using glycerol as a substrate in bloodstream-form Trypanosoma brucei. PLoS Pathogens, 14(12), e1007475. (doi: 10.1371/journal.ppat.1007475) (PMID:30589893) (PMCID:PMC6307712)

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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.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Ferguson, Professor Michael and Kovarova, Ms Julie and Barrett, Professor Michael
Creator Roles:
Kovářová, J.Conceptualization, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review and editing
Ferguson, M. A.J.Conceptualization, Supervision, Writing – original draft, Writing – review and editing
Barrett, M. P.Conceptualization, Supervision, Writing – original draft, Writing – review and editing
Authors: Kovářová, J., Nagar, R., Faria, J., Ferguson, M. A.J., Barrett, M. P., and Horn, D.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:PLoS Pathogens
Publisher:Public Library of Science
ISSN (Online):1553-7374
Published Online:27 December 2018
Copyright Holders:Copyright © 2018 Kovářová et al.
First Published:First published in PLoS Pathogens 14(12): e1007475
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
170547The Wellcome Centre for Molecular Parasitology ( Core Support )Andrew WatersWellcome Trust (WELLCOTR)104111/Z/14/ZRIII - Parasitology