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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.

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.

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 K_0.5 and V_max values of 0.016±0.002mM and 564.9±18.06pmol×h⁻¹×10⁻⁷cells, 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 …