title: Fumarate is an essential intermediary metabolite produced by the procyclic Trypanosoma brucei.
abstract: The procyclic stage of Trypanosoma brucei, a parasitic protist responsible for sleeping sickness in humans, converts most of the consumed glucose into excreted succinate, by succinic fermentation. Succinate is produced by the glycosomal and mitochondrial NADH-dependent fumarate reductases, which are not essential for parasite viability. To further explore the role of the succinic fermentation pathways, we studied the trypanosome fumarases, the enzymes providing fumarate to fumarate reductases. The T. brucei genome contains two class I fumarase genes encoding cytosolic (FHc) and mitochondrial (FHm) enzymes, which account for total cellular fumarase activity as shown by RNA interference. The growth arrest of a double RNA interference mutant cell line showing no fumarase activity indicates that fumarases are essential for the parasite. Interestingly, addition of fumarate to the medium rescues the growth phenotype, indicating that fumarate is an essential intermediary metabolite of the insect stage trypanosomes. We propose that trypanosomes use fumarate as an essential electron acceptor, as exemplified by the fumarate dependence previously reported for an enzyme of the essential de novo pyrimidine synthesis (Takashima, E., Inaoka, D. K., Osanai, A., Nara, T., Odaka, M., Aoki, T., Inaka, K., Harada, S., and Kita, K. (2002) Mol. Biochem. Parasitol. 122, 189-200).
authors.affiliation: Laboratoire de Génomique Fonctionnelle des Trypanosomatides, UMR-5162 CNRS and Résonance Magnétique des Systèmes Biologiques, UMR-5536 CNRS, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Coustou
authors.forename: Marc
authors.initials: M
authors.lastname: Biran
authors.forename: Sébastien
authors.initials: S
authors.lastname: Besteiro
authors.forename: Loïc
authors.initials: L
authors.lastname: Rivière
authors.forename: Théo
authors.initials: T
authors.lastname: Baltz
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Franconi
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bringaud
mesh_terms: D000818:Animals; D003600:Cytosol / Q000201:enzymology; D004583:Electrons; D005650:Fumarates / Q000737:chemistry*; D005947:Glucose / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008830:Microbodies / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D009154:Mutation; D010802:Phylogeny; D020033:Protein Isoforms; D034622:RNA Interference; D013997:Time Factors; D014346:Trypanosoma brucei brucei / Q000378:metabolism*
chemical_list: D005650:Fumarates; D020033:Protein Isoforms; D049452:Green Fluorescent Proteins; C032005:fumaric acid; D005947:Glucose