A plant‐like vacuolar H+‐pyrophosphatase in Plasmodium falciparum

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Abstract
Inorganic pyrophosphate promoted the acidification of a subcellular compartment in cell homogenates of Plasmodium falciparum trophozoites. The proton gradient driven by pyrophosphate was collapsed by addition of NH4Cl or the K+/H+ exchanger nigericin and eliminated by the pyrophosphate analog aminomethylenediphosphonate. Pyrophosphatase activity was dependent upon K+, and partially inhibited by Na+. The presence of a plant‐like vacuolar H+‐translocating pyrophosphatase (V‐H+‐PPase) was confirmed using antibodies raised against conserved peptide sequences of the enzyme, which cross reacted with a protein band of 76.5 kDa. Immunofluorescence microscopy using these antibodies showed a general fluorescence over the whole parasites and intracellular bright spots suggesting a vesicular and plasma membrane localization. Together, these results indicate the presence in P. falciparum of a V‐H+‐PPase of similar characteristics to those of the enzyme from plants.