The reduced incidence of malaria has been helped through the widespread use of artemisinins (ARTs) but the emergence ART resistance remains an ongoing threat to malarial control. Several lines of evidence indicate that artemisinin resistance is mediated, at least in part, by altered protein turnover dynamics[1,2]. To investigate how ART-resistant parasites are capable of overcoming artemisinin-induced toxicity we developed a pulse-SILAC (stable isotope labelling amino acid in cell culture) approach that is capable of quantifying the rates of protein turnover across the proteome. We observe that following ART exposure, both sensitive and resistant lines have impaired protein turnover that affects all detectable proteins. However, ART-resistant lines begin recovering protein turnover after 12 hours post drug exposure, with increased turnover of proteins associated with protein folding, translation and response to oxidative stress. Interestingly, this difference in parasite recovery at 12-18 hours post-artemisinin treatment occurs while EIF2-alpha phosphorylation remains elevated, suggesting that the link between EIF2-alpha phosphorylation, translational repression, and artemisinin resistance is more complicated than previously thought.
To further understand how resistant parasites may overcome artemisinin exposure we developed an extension to the pulse-SILAC method which can reliably measure protein translation, synthesis and turnover in a single experiment. We present how this triplex pulse-SILAC approach can reveal which aspects of protein homeostasis are disrupted following mis-localisation of kelch13 away from its native location and suggest a possible mechanism of kelch13-associated artemisinin resistance.