Plasmodium falciparum Niemann-Pick Type C1-Related Protein is a Druggable Target Required for Parasite Membrane Homeostasis

Abstract

Plasmodium parasites possess a protein with homology to Niemann-Pick Type C1 proteins (Plasmodium falciparum Niemann-Pick Type C1-Related protein, PfNCR1). We isolated parasites with resistance-conferring mutations in PfNCR1 during selections with three diverse small-molecule antimalarial compounds and show that the mutations are causative for compound resistance. PfNCR1 protein knockdown results in severely attenuated growth and confers hypersensitivity to the compounds. Compound treatment or protein knockdown leads to increased sensitivity of the parasite plasma membrane (PPM) to the amphipathic glycoside saponin and engenders digestive vacuoles (DVs) that are small and malformed. Immunoelectron microscopy and split-GFP experiments localize PfNCR1 to the PPM. Our experiments show that PfNCR1 activity is critically important for the composition of the PPM and is required for DV biogenesis, suggesting PfNCR1 as a novel antimalarial drug target.

Diverse chemical compounds target Plasmodium falciparum plasma membrane lipid homeostasis

“…Alternatively, this pathway may remove any cholesterol that diffuses into the plasma membrane. PfNCR1 has been implicated as the lipid transporter responsible for maintaining the plasma membrane lipid homeostasis 13 . PfNCR1 may also serve to maintain sphingomyelin levels in the PPM similar to the function of T. gondii NCR1 in the inner membrane complex of Toxoplasma 27 .…”

“…berghei NCR1 deletions were shown to be lethal to the parasite 13,28 . This highlights the need for parasites to maintain appropriate cholesterol/lipid composition within the plasma membrane.…”

“…Recently, a chemogenetic screen of the Malaria Box compounds found that resistance towards MMV009108 and MMV019662 required mutations in the gene PF3D7_0107500, now called Plasmodium falciparum Niemann-Pick Type C1-Related Protein (PfNCR1) [12][13] .…”

“…MMV009108 was able to reversibly induce saponin sensitivity without disrupting parasite Na + homeostasis 13 . Furthermore, we showed that MMV009108 and MMV019662 caused parasite death via the inhibition of PfNCR1 13 .…”

“…al. 13 . Briefly, a right homologous region (bp3671 -bp4893) and a left homologous region (a 948bp fragment starting 38bp past the stop codon) were amplified by PCR from gDNA and cloned into the vector pMG75.…”