title: Transport of inorganic phosphate in Leishmania infantum and compensatory regulation at low inorganic phosphate concentration.
abstract: BACKGROUND
  Proliferation of Leishmania infantum depends on exogenous inorganic phosphate (P(i)) but little is known about energy metabolism and transport of P(i) across the plasma membrane in Leishmania sp.
  
  
  METHODS
  We investigated the kinetics of 32P(i) transport, the influence of H+ and K+ ionophores and inhibitors, and expression of the genes for the Na+:P(i) and H+:P(i) cotransporters.
  
  
  RESULTS
  The proton ionophore FCCP, bafilomycin A1 (vacuolar ATPase inhibitor), nigericin (K+ ionophore) and SCH28080 (an inhibitor of H+, K(+)-ATPase) all inhibited the transport of P(i). This transport showed Michaelis-Menten kinetics with K0.5 and V(max) values of 0.016 +/- 0.002 mM and 564.9 +/- 18.06 pmol x h(-1) x 10(-7) cells, respectively. These values classify the P(i) transporter of L. infantum among the high-affinity transporters, a group that includes Pho84 of Saccharomyces cerevisiae. Two sequences were identified in the L. infantum genome that code for phosphate transporters. However, transcription of the PHO84 transporter was 10-fold higher than the PHO89 transporter in this parasite. Accordingly, P(i) transport and LiPho84 gene expression were modulated by environmental P(i) variations.
  
  
  CONCLUSIONS
  These findings confirm the presence of a P(i) transporter in L. infantum, similar to PHO84 in S. cerevisiae, that contributes to the acquisition of inorganic phosphate and could be involved in growth and survival of the promastigote forms of L. infantum.
  
  
  CONCLUSIONS
  This work provides the first description of a PHO84-like P(i) transporter in a Trypanosomatide parasite of the genus Leishmania, responsible for many infections worldwide.
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.
authors.forename: T
authors.initials: T
authors.lastname: Russo-Abrahão
authors.forename: M
authors.initials: M
authors.lastname: Alves-Bezerra
authors.forename: D
authors.initials: D
authors.lastname: Majerowicz
authors.forename: A L
authors.initials: AL
authors.lastname: Freitas-Mesquita
authors.forename: C F
authors.initials: CF
authors.lastname: Dick
authors.forename: K C
authors.initials: KC
authors.lastname: Gondim
authors.forename: J R
authors.initials: JR
authors.lastname: Meyer-Fernandes
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D003470:Culture Media; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D007700:Kinetics; D018314:Leishmania infantum / Q000201:enzymology* / Q000235:genetics; D018942:Macrolides / Q000494:pharmacology; D008969:Molecular Sequence Data; D009550:Nigericin / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism* / Q000494:pharmacology; D010761:Phosphorus Radioisotopes; D010802:Phylogeny; D061209:Proton Ionophores / Q000494:pharmacology; D028081:Proton-Phosphate Symporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D050608:Sodium-Phosphate Cotransporter Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D003470:Culture Media; D004791:Enzyme Inhibitors; D007093:Imidazoles; D018942:Macrolides; C105495:PHO84 protein, S cerevisiae; D010710:Phosphates; D010761:Phosphorus Radioisotopes; D061209:Proton Ionophores; D028081:Proton-Phosphate Symporters; D015800:Protozoan Proteins; D029701:Saccharomyces cerevisiae Proteins; D050608:Sodium-Phosphate Cotransporter Proteins; C035235:Sch 28080; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; C040929:bafilomycin A1; D025262:Vacuolar Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D009550:Nigericin