Follow the drug: Unravelling specificity and activity of antimalarial pantothenamides
Treatment-resistant malaria parasites are an increasing problem, and very few drugs target liver-, and sexual-stage parasites (gametocytes), underlining the need for novel antimalarials. MMV693183, a so-called pantothenamide (PanAm), is a promising compound developed in Nijmegen that kills asexual blood-stage parasites and female gametocytes at nanomolar concentrations [PMID:31534021,34969059]. PanAms are analogues of pantothenate, the precursor of the essential cofactor co-enzyme A (CoA), and have a completely novel mechanism of action. Once taken up by the parasite through an as yet unknown pathway, these compounds are converted into CoA-PanAms that inhibit the enzyme acetyl-CoA synthetase (ACS). While CoA-PanAm-mediated ACS inhibition leads to reduced acetyl-CoA levels in the parasite, the downstream consequences and mode of killing remain unexplored.
In this project, we aim to elucidate why PanAms effectively kill parasites but not human cells, and female but not male gametocytes. We hypothesize that the answers to these questions lie in the understanding of (1) the uptake mechanism of PanAms into the parasite and (2) the downstream consequences of ACS inhibition. Here, we will focus on the former from both parasite and drug perspective. We will use CRISPR-Cas9-based conditional knock-down mutants combined with drug-sensitivity assays (in collaboration with Dr. Koen Dechering, TropIQ) to study the role of candidate PanAm transporters. Together with Dr. Willem Velema (FNWI), we will use click chemistry to generate fluorescent PanAms to trace their localization by state-of-the-art microscopy in different life-cycle stages. Furthermore, we will modify PanAms for photoaffinity labeling. Following cross-linking of the PanAms to their interaction partners by UV-irradiation, the latter can be identified by mass spectrometry [PMID:25686004]. With this project, we take a critical step in understanding the mode of action of PanAms, and thereby contribute to WHO’s mission ‘to rid the world of 90% of the burden of death and disease due to malaria by 2030’.
Taco Kooij 