Targeting Plasmodium signal peptide peptidase as a novel source of anti-malarials

Malaria, caused by the protozoan parasite Plasmodium, continues to be a major global health burden. Current treatments are failing due to rising drug resistance, necessitating the development of new therapeutics. Recent literature has been investigating the targetability of Plasmodium Signal Peptide Peptidase (SPP), an aspartic protease that cleaves peptides in the endoplasmic reticulum membrane and is conserved across eukaryotes. Previous studies have reported five SPP inhibitors that kill Plasmodium and have limited potency against human cell lines. Most of these inhibitors were originally designed to target another member of the aspartyl intramembrane protease family, presenilin of the gamma-secretase complex. Aim 1.1: A human cell-based PfSPP activity assay will be used to screen approximately 1,400 compounds for their ability to inhibit PfSPP’s protease activity. Aim 1.2: For the 10 most potent compounds, EC50 values will be determined in wild-type, PfSPP knockdown, and PfSPP overexpressing P. falciparum to ensure the compounds target SPP in Plasmodium and result in parasite death. Additionally, this proposal aims to improve understanding of a PfSPP transition state analog inhibitor, L685,458, which is suspected to inhibit additional Plasmodium proteins due to its unique phenotypes when compared to other PfSPP inhibitors. Aim 2.1: Parasites resistant to L685,458 have been generated via growth of P. falciparum in the compound. Clones will be identified that are resistant to L685,458 but not to other PfSPP inhibitors. By sequencing the genomic DNA of these parasites, candidate proteins that may be additional targets of L685,458 will be identified. Aim 2.2: P. falciparum conditional knockdown lines of the candidate proteins will be generated. The EC50 of L685,458 will be determined in wild-type and knockdown parasites to confirm that these candidate proteins are targets or modulators of L685,458. Overall, this work aims to identify more potent and clinically promising PfSPP inhibitors via the first broad compound screen and to improve understanding of the interesting off-target effects of L685,458.

Basic Science

Jan 2024 — Dec 2025

$67,388

United States