Transcriptome-wide dynamics of extensive mA mRNA methylation during Plasmodium falciparum blood-stage development.

Malaria pathogenesis results from the asexual replication of Plasmodium falciparum within human red blood cells, which relies on a precisely timed cascade of gene expression over a 48-h life cycle. Although substantial post-transcriptional regulation of this hardwired program has been observed, it remains unclear how these processes are mediated on a transcriptome-wide level. To this end, we identified mRNA modifications in the P. falciparum transcriptome and performed a comprehensive characterization of N-methyladenosine (mA) over the course of blood-stage development. Using mass spectrometry and mA RNA sequencing, we demonstrate that mA is highly developmentally regulated, exceeding mA levels known in any other eukaryote. We characterize a distinct mA writer complex and show that knockdown of the putative mA methyltransferase, PfMT-A70, by CRISPR interference leads to increased levels of transcripts that normally contain mA. In accordance, we find an inverse correlation between mA methylation and mRNA stability or translational efficiency. We further identify two putative mA-binding YTH proteins that are likely to be involved in the regulation of these processes across the parasite's life cycle. Our data demonstrate unique features of an extensive mA mRNA methylation programme in malaria parasites and reveal its crucial role in dynamically fine-tuning the transcriptional cascade of a unicellular eukaryote.