Authors

Discussion

Artemisinin susceptibility in Plasmodium falciparum is modulated by mutations in the gene pfk13, which encodes a kelch propeller domain protein of unknown function. Reduced susceptibility is demonstrated in vitro by elevated parasite survival after short exposures to physiologic concentrations of drug in the early ring stage. Using CRISPR-Cas9 genome editing, we provide the first evidence of a similar but K13-independent in vitro artemisinin resistance caused by a single base change in locus encoding the AP-2 adaptor complex mu-subunit (pfap2mu). Through extensive fluorescence and electron microscopy and proteomics, our functional characterisation of PfAP2mu validates that gene as encoding a clathrin-independent, non-canonical AP-2 trafficking factor that interacts with K13 and other important factors at a distal face of the ER and is essential for asexual parasite survival. We show that disruption of trafficking in early rings initiates an ER-based stress response that underlies artemisinin resistance and induced dormancy. A model depicting a role for ER trafficking components in ring-stage artemisinin action is proposed and implications for controlling multi-drug resistance in natural parasite populations will be discussed.