University of Oulu

Millerioux Y, Mazet M, Bouyssou G, Allmann S, Kiema T-R, Bertiaux E, et al. (2018) De novo biosynthesis of sterols and fatty acids in the Trypanosoma brucei procyclic form: Carbon source preferences and metabolic flux redistributions. PLoS Pathog 14(5): e1007116.

De novo biosynthesis of sterols and fatty acids in the Trypanosoma brucei procyclic form : carbon source preferences and metabolic flux redistributions

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Author: Millerioux, Yoann1,2; Mazet, Muriel1,2; Bouyssou, Guillaume3;
Organizations: 1Laboratoire de Microbiologie Fondamentale et Pathogénicité (MFP), Université de Bordeaux
2Centre de Résonance Magnétique des Systèmes Biologiques (RMSB), Université de Bordeaux
3Membrane Biogenesis Laboratory, CNRS-University of Bordeaux
4Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu
5Trypanosome Transmission Group, Trypanosome Cell Biology Unit, Department of Parasites and Insect Vectors, INSERM U1201, Institut Pasteur
6Metabolome Facility of Bordeaux, Functional Genomics Center
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 6.9 MB)
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Language: English
Published: Public Library of Science, 2018
Publish Date: 2018-08-28


De novo biosynthesis of lipids is essential for Trypanosoma brucei, a protist responsible for the sleeping sickness. Here, we demonstrate that the ketogenic carbon sources, threonine, acetate and glucose, are precursors for both fatty acid and sterol synthesis, while leucine only contributes to sterol production in the tsetse fly midgut stage of the parasite. Degradation of these carbon sources into lipids was investigated using a combination of reverse genetics and analysis of radio-labelled precursors incorporation into lipids. For instance, (i) deletion of the gene encoding isovaleryl-CoA dehydrogenase, involved in the leucine degradation pathway, abolished leucine incorporation into sterols, and (ii) RNAi-mediated down-regulation of the SCP2-thiolase gene expression abolished incorporation of the three ketogenic carbon sources into sterols. The SCP2-thiolase is part of a unidirectional two-step bridge between the fatty acid precursor, acetyl-CoA, and the precursor of the mevalonate pathway leading to sterol biosynthesis, 3-hydroxy-3-methylglutaryl-CoA. Metabolic flux through this bridge is increased either in the isovaleryl-CoA dehydrogenase null mutant or when the degradation of the ketogenic carbon sources is affected. We also observed a preference for fatty acids synthesis from ketogenic carbon sources, since blocking acetyl-CoA production from both glucose and threonine abolished acetate incorporation into sterols, while incorporation of acetate into fatty acids was increased. Interestingly, the growth of the isovaleryl-CoA dehydrogenase null mutant, but not that of the parental cells, is interrupted in the absence of ketogenic carbon sources, including lipids, which demonstrates the essential role of the mevalonate pathway. We concluded that procyclic trypanosomes have a strong preference for fatty acid versus sterol biosynthesis from ketogenic carbon sources, and as a consequence, that leucine is likely to be the main source, if not the only one, used by trypanosomes in the infected insect vector digestive tract to feed the mevalonate pathway.

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Series: PLoS pathogens
ISSN: 1553-7366
ISSN-E: 1553-7374
ISSN-L: 1553-7366
Volume: 14
Issue: 5
Article number: e1007116
DOI: 10.1371/journal.ppat.1007116
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: This research was supported by the Centre National de la Recherche Scientifique (CNRS), the Université de Bordeaux, the Agence Nationale de la Recherche (ANR) through grants ACETOTRYP (grant number ANR-2010-BLAN-1319-02) of the ANR-BLANC-2010 call and GLYCONOV (grant number ANR-15-CE15-0025-01) of the "Générique" 2015 call, the Laboratoire d’Excellence (LabEx) ParaFrap (grant number ANR-11-LABX-0024), the Institut Pasteur and by the European Commission FP7 Marie Curie Initial Training Network "ParaMet" (grant number 290080). EB was funded by a doctoral fellowship from French National Ministry for Research and Technology (doctoral school CDV515). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Copyright information: © 2018 Millerioux et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.