Authors

H Eavis¹; H Johnston¹; R Antrobus¹; R Nakamura¹; K Artavanis-Tsakonas¹;  ¹ University of Cambridge, UK

Discussion

Resistance to the front-line antimalarial drug artemisinin in Plasmodium falciparum is closely linked to the parasite’s essential process of haemoglobin uptake via endocytosis. The parasite internalises host haemoglobin through a plasma membrane invagination known as the cytostome, after which it is trafficked to the food vacuole and digested into heme - the molecule responsible for activating artemisinin. Mutations that confer artemisinin resistance cluster in proteins associated with the cytostome, including the key resistance markers Kelch13, UBP1, and EPS15. Notably, these proteins have established or strongly suspected roles in the ubiquitin pathway in human homologues, suggesting that disruption of ubiquitin-mediated regulation of endocytosis underpins the parasite’s ability to evade artemisinin-mediated killing. We combine a resistance-conferring conditional mutation of the deubiquitinase UBP1 with proximity-based biotinylation of proteins within the endosomal trafficking pathway (PerturboID). By comparing protein recruitment to the cytostome and subsequent downstream trafficking in wild-type and mutant UBP1 parasites, we aim to identify UBP1 substrates and define the molecular basis of the ubiquitin pathway in endocytosis and drug resistance.