Transport of inorganic phosphate in Leishmania infantum and compensatory regulation at low inorganic phosphate concentration

• Published in: Biochimica et biophysica acta Vol. 1830; no. 3; pp. 2683 - 2689
• Main Authors: Russo-Abrahão, T., Alves-Bezerra, M., Majerowicz, D., Freitas-Mesquita, A.L., Dick, C.F., Gondim, K.C., Meyer-Fernandes, J.R.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2013
• Subjects: energy metabolism; enzyme kinetics; gene expression; genome; H-transporting ATP synthase; Leishmania infantum; nigericin; parasites; phosphates; Pi starvation; Pi transporter; plasma membrane; potassium; protons; Saccharomyces cerevisiae; transporters; BHI; Leishmania infantum; LiPho89; HEPES; FCS; LiPho84; FCCP; Pi transporter; Pi starvation; P(i) starvation; P(i) transporter
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2012.11.017

Proliferation of Leishmania infantum depends on exogenous inorganic phosphate (Pi) but little is known about energy metabolism and transport of Pi across the plasma membrane in Leishmania sp. We investigated the kinetics of 32Pi transport, the influence of H+ and K+ ionophores and inhibitors, and expression of the genes for the Na+:Pi and H+:Pi cotransporters. 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 Pi. This transport showed Michaelis–Menten kinetics with K0.5 and Vmax values of 0.016±0.002mM and 564.9±18.06pmol×h−1×10−7cells, respectively. These values classify the Pi 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, Pi transport and LiPho84 gene expression were modulated by environmental Pi variations. These findings confirm the presence of a Pi 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. This work provides the first description of a PHO84-like Pi transporter in a Trypanosomatide parasite of the genus Leishmania, responsible for many infections worldwide. ► The Pi transporter in L. infantum is a high-affinity transporter. ► The Pi transporter in L. infantum is regulated by extracellular Pi concentration. ► The Pi transporter in L. infantum is similar to PHO84 in S. cerevisiae.