Impact of field isolate identified non-synonymous single nucleotide polymorphisms on Plasmodium falciparum Equilibrative Nucleoside Transporter 1 (PfENT1) inhibitor efficacy.

Plasmodium falciparum causes the most severe form of malaria and causes approximately 500,000 deaths per year. P. falciparum parasites resistant to current anti-malarial treatments are spreading. Therefore, it is imperative to develop new anti-malarial drugs. Malaria parasites are purine auxotrophic. They rely on purine import from the host erythrocyte via Equilibrative Nucleoside Transporters (ENTs). Recently, inhibitors of the P. falciparum ENT1 (PfENT1) that inhibit proliferation of malaria parasites in culture have been identified as promising starting points for antimalarial drug development. Genome sequencing of P. falciparum field isolates has identified non-synonymous single nucleotide polymorphisms (SNPs) in the gene encoding PfENT1. Here we evaluate the impact of these PfENT1 SNPs on purine substrate affinity and inhibitor efficacy. We expressed each PfENT1-SNP in Saccharomyces cerevisiae. Using PfENT1-SNP-expressing yeast, we characterized the PfENT1 purine substrate affinity using radiolabeled...