Sodium-dependent uptake of inorganic phosphate by the intracellular malaria parasite

Nature. 2006 Oct 5;443(7111):582-5. doi: 10.1038/nature05149. Epub 2006 Sep 27.


As the malaria parasite, Plasmodium falciparum, grows within its host erythrocyte it induces an increase in the permeability of the erythrocyte membrane to a range of low-molecular-mass solutes, including Na+ and K+ (ref. 1). This results in a progressive increase in the concentration of Na+ in the erythrocyte cytosol. The parasite cytosol has a relatively low Na+ concentration and there is therefore a large inward Na+ gradient across the parasite plasma membrane. Here we show that the parasite exploits the Na+ electrochemical gradient to energize the uptake of inorganic phosphate (P(i)), an essential nutrient. P(i) was taken up into the intracellular parasite by a Na+-dependent transporter, with a stoichiometry of 2Na+:1P(i) and with an apparent preference for the monovalent over the divalent form of P(i). A P(i) transporter (PfPiT) belonging to the PiT family was cloned from the parasite and localized to the parasite surface. Expression of PfPiT in Xenopus oocytes resulted in Na+-dependent P(i) uptake with characteristics similar to those observed for P(i) uptake in the parasite. This study provides new insight into the significance of the malaria-parasite-induced alteration of the ionic composition of its host cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport / drug effects
  • Erythrocytes / drug effects
  • Erythrocytes / parasitology
  • Hydrogen-Ion Concentration
  • Kinetics
  • Malaria / parasitology*
  • Oocytes
  • Phosphate Transport Proteins / metabolism*
  • Phosphates / metabolism*
  • Phylogeny
  • Plasmodium falciparum / drug effects*
  • Plasmodium falciparum / metabolism*
  • Saponins / pharmacology
  • Sodium / pharmacology*
  • Xenopus


  • Phosphate Transport Proteins
  • Phosphates
  • Saponins
  • Sodium