Abstract
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-hour 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 N6-methyladenosine (m6A) over the course of blood stage development. Using mass spectrometry and m6A RNA sequencing, we demonstrate that m6A is highly developmentally regulated, exceeding m6A levels known in any other eukaryote. We identify an evolutionarily conserved m6A writer complex and show that knockdown of the putative m6A methyltransferase by CRISPR interference leads to increased levels of transcripts that normally contain m6A. In accordance, we find an inverse correlation between m6A status and mRNA stability or translational efficiency. Our data reveal the crucial role of extensive m6A mRNA methylation in dynamically fine-tuning the transcriptional program of a unicellular eukaryote as well as a new ‘epitranscriptomic’ layer of gene regulation in malaria parasites.
