Epitranscriptomic Dysregulation Underpins Artemisinin Mechanism of Action.

Artemisinin has long been a first-line antimalarial. Yet, its mode of action is still poorly understood. Emergence of artemisinin-resistant strains highlight the importance of addressing this question so as to develop better drugs and overcome resistance. In this study, we performed RNA-sequencing and proteomics studies on artemisinin treated parasites indicated a striking difference in the codon-usage pattern of differentially translated genes. Using a liquid chromatography-coupled mass spectrometry (LC-MS)-based platform, we have quantified the full spectrum of modified ribonucleosides on tRNA in in response to the drug. We found that N-threonyl-carbomyladenosine (tA), a universal tRNA modification found at position 37 is hypomodified in response to artemisinin induced stress. Additionally, we also found that artemisinin treatment resulted in a downregulation of PfSua5, an enzyme involved in the tA biosynthesis machinery. These findings provide new insights into how artemisinin works. More broadly, the findings exposes the tRNA epitranscriptome as a vulnerability in the parasite that can be exploited for new drugs.