Cytosine methylation of tRNA in Plasmodium falciparum disrupts translational homeostasis to prime for sexual commitment

Malaria parasites have evolved a well-adjusted developmental program to progress through the complex life cycle in the human and mosquito host. Here we identify cytosine methylation of tRNAAsp (GTC) as being critical to maintain stable protein synthesis under cellular stress. Using conditional knock out of a member of the DNA methyltransferases family called Pf-DNMT2, RNA bisulfite sequencing demonstrates the selective cytosine methylation of this enzyme of tRNAAsp (GTC) at position C38. Although no growth defect on parasite asexual proliferation was observed, Pf-DNMT2 KO parasites show a striking increase in their sexual commitment and an increased sensitivity to Dihydroartemisinin. In mutant parasites we observe a dramatic decrease of tRNAAsp (GTC) when compared to non-stressed parasites and mass spectrometry analysis shows the selective downregulation of proteins with GAC codon bias. Here we identify an epitranscriptomic mechanism that safeguards protein translation and homeostasis of sexual commitment during cellular stress in malaria parasites