title: H+-dependent inorganic phosphate uptake in Trypanosoma brucei is influenced by myo-inositol transporter.
abstract: Trypanosoma brucei is an extracellular protozoan parasite that causes human African trypanosomiasis or "sleeping sickness". During the different phases of its life cycle, T. brucei depends on exogenous inorganic phosphate (Pi), but little is known about the transport of Piin this organism. In the present study, we showed that the transport of32Piacross the plasma membrane follows Michaelis-Menten kinetics and is modulated by pH variation, with higher activity at acidic pH. Bloodstream forms presented lower Pitransport in comparison to procyclic forms, that displayed an apparent K0.5= 0.093 ± 0.008 mM. Additionally, FCCP (H+-ionophore), valinomycin (K+-ionophore) and SCH28080 (H+, K+-ATPase inhibitor) inhibited the Pitransport. Gene Tb11.02.3020, previously described to encode the parasite H+:myo-inositol transporter (TbHMIT), was hypothesized to be potentially involved in the H+:Picotransport because of its similarity with the Pho84 transporter described in S. cerevisiae and other trypanosomatids. Indeed, the RNAi mediated knockdown remarkably reduced TbHMIT gene expression, compromised cell growth and decreased Pitransport by half. In addition, Pitransport was inhibited when parasites were incubated in the presence of concentrations of myo-inositol that are above 300 μM. However, when expressed in Xenopus laevis oocytes, two-electrode voltage clamp experiments provided direct electrophysiological evidence that the protein encoded by TbHMIT is definitely a myo-inositol transporter that may be only marginally affected by the presence of Pi. These results confirmed the presence of a Picarrier in T. brucei, similar to the H+-dependent inorganic phosphate system described in S. cerevisiae and other trypanosomatids. This transport system contributes to the acquisition of Piand may be involved in the growth and survival of procyclic forms. In summary, this work presents the first description of a Pitransport system in T. brucei.
authors.affiliation: Instituto de Microbiologia Professor Paulo de Góes, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.|Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil.
authors.forename: Thais
authors.initials: T
authors.lastname: Russo-Abrahão
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.
authors.forename: Carolina Macedo
authors.initials: CM
authors.lastname: Koeller
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, 3012, Bern, Switzerland.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Steinmann
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Silva-Rito
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil.
authors.forename: Thaissa
authors.initials: T
authors.lastname: Marins-Lucena
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.|Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil.
authors.forename: Michele
authors.initials: M
authors.lastname: Alves-Bezerra
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil.
authors.forename: Naira Ligia
authors.initials: NL
authors.lastname: Lima-Giarola
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.|Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil.
authors.forename: Iron Francisco
authors.initials: IF
authors.lastname: de-Paula
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, 3012, Bern, Switzerland.
authors.forename: Amaia
authors.initials: A
authors.lastname: Gonzalez-Salgado
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, 3012, Bern, Switzerland.
authors.forename: Erwin
authors.initials: E
authors.lastname: Sigel
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, 3012, Bern, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Bütikofer
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil.|Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil.
authors.forename: Katia Calp
authors.initials: KC
authors.lastname: Gondim
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil. nheise@biof.ufrj.br.
authors.forename: Norton
authors.initials: N
authors.lastname: Heise
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil. meyer@bioqmed.ufrj.br.|Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ, Brazil. meyer@bioqmed.ufrj.br.
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Meyer-Fernandes
mesh_terms: D001692:Biological Transport; D055724:Electrophysiological Phenomena; D006863:Hydrogen-Ion Concentration; D007294:Inositol / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D010710:Phosphates / Q000378:metabolism / Q000493:pharmacokinetics*; D015800:Protozoan Proteins / Q000378:metabolism*; D027981:Symporters / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000378:metabolism*
chemical_list: D010710:Phosphates; D015800:Protozoan Proteins; D027981:Symporters; D007294:Inositol
keywords: Inorganic phosphate; Pi transporter system; Trypanosoma brucei