title: Characterization of choline uptake in Trypanosoma brucei procyclic and bloodstream forms.
abstract: Choline is an essential nutrient for eukaryotic cells, where it is used as precursor for the synthesis of choline-containing phospholipids, such as phosphatidylcholine (PC). According to published data, Trypanosoma brucei parasites are unable to take up choline from the environment but instead use lyso-phosphatidylcholine as precursor for choline lipid synthesis. We now show that T. brucei procyclic forms in culture readily incorporate [(3)H]-labeled choline into PC, indicating that trypanosomes express a transporter for choline at the plasma membrane. Characterization of the transport system in T. brucei procyclic and bloodstream forms shows that uptake of choline is independent of sodium and potassium ions and occurs with a Km in the low micromolar range. In addition, we demonstrate that choline uptake can be blocked by the known choline transport inhibitor, hemicholinium-3, and by synthetic choline analogs that have been established as anti-malarials. Together, our results show that T. brucei parasites express an uptake system for choline and that exogenous choline is used for PC synthesis.
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, 3012 Bern, Switzerland.
authors.forename: Juan P
authors.initials: JP
authors.lastname: Macêdo
authors.forename: Remo S
authors.initials: RS
authors.lastname: Schmidt
authors.forename: Pascal
authors.initials: P
authors.lastname: Mäser
authors.forename: Doris
authors.initials: D
authors.lastname: Rentsch
authors.forename: Henri J
authors.initials: HJ
authors.lastname: Vial
authors.forename: Erwin
authors.initials: E
authors.lastname: Sigel
authors.forename: Peter
authors.initials: P
authors.lastname: Bütikofer
mesh_terms: D000818:Animals; D001692:Biological Transport; D002417:Cattle; D002794:Choline / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D014353:Trypanosomiasis, African / Q000469:parasitology*
chemical_list: D026901:Membrane Transport Proteins; D010713:Phosphatidylcholines; D015800:Protozoan Proteins; D002794:Choline
keywords: CTL; Choline; HC-3; Kinetics; PC; Phosphatidylcholine; TLC; Transport; Trypanosoma; choline transporter-like; hemicholinium-3; lyso-PC; lyso-phosphatidylcholine; phosphatidylcholine; thin layer chromatography