Abstract
Pyrophosphate is a byproduct of numerous cellular reactions that use ATP or other nucleoside triphosphates to synthesize DNA, RNA, protein, and other molecules. Its degradation into monophosphate is thus crucial for the survival and proliferation of all life forms. The human malaria parasite Plasmodium falciparum encodes two classes of pyrophosphatases to hydrolyze pyrophosphate. The first consists of P. falciparum proton pumping vacuolar pyrophosphatases (PfVP1 and PfVP2), which localize to the parasite's subcellular membranes and work as proton pumps. The second includes P. falciparum soluble pyrophosphatases (PfsPPases), which have not been well characterized. Interestingly, the gene locus of PfsPPase encodes two isoforms, PfsPPase1 (PF3D7_0316300.1) and PfsPPase2 (PF3D7_0316300.2). PfsPPase2 contains a 51-amino acid organellar localization peptide that is absent in PfsPPase1. Here, we combine reverse genetics and biochemical approaches to identify the localization of PfsPPase1 and PfsPPase2 and elucidate their individual functions. We show that PfsPPases are essential for the asexual blood stage. While PfsPPase1 solely localizes to the cytoplasm, PfsPPase2 exhibits multiple localizations including the mitochondrion, the apicoplast, and, to a lesser extent, the cytoplasm. Our data suggest that P. falciparum has taken a unique evolutionary trajectory in pyrophosphate metabolism by utilizing a leader sequence to direct sPPases to the mitochondrion and apicoplast. This differs from model eukaryotes as they generally encode multiple sPPases at distinct genetic loci to facilitate pyrophosphate degradation in cytosolic and organellar compartments. Our study highlights PfsPPases as promising targets for the development of novel antimalarial drugs.