The phylogenetic group Apicomplexans include some of the most important protist parasites that play an important role in human health. Despite their global impact, they are understudied, which allows these parasites to continue to burden resource poor communities. Many of these parasites have a complex lifecycle such as the parasite that causes malaria, Plasmodium falciparum. This requires the parasite to rapidly adapt to many environments.
The parasite achieves this through dynamic regulation of gene expression as seen through transcriptomics studies. Precise regulation of gene expression is also critical within each developmental stage e.g., the cascading pattern of gene expression in the pathogenic, intraerythrocytic development cycle (IDC). The mechanisms of regulating gene expression within the IDC are poorly understood. The number of transcription factors in the genome of Plasmodium falciparum is one of the lowest among studied organisms. Therefore, it is apparent that there are other mechanisms of regulation that play an essential role.
One such mechanism that has gained attention is post-transcriptional (epitranscriptional) modification of mRNA, particularly the N6-methyladenosine (m6A) modification of adenosine catalysed by the evolutionarily conserved m6A writer complex. It is believed that m6A enrichment affects mRNA stability leading to faster degradation of transcripts, resulting in lower abundance and decreased translation. Studied in this field have been limited by the limited availability of inducible knockdown systems for this essential complex.
In this study we adapt knock-sideways to conditionally knockdown components of the m6A writer and study the resulting phenotypes. We report that the m6A writer is essential concurring with the work of Baumgarten et al. (2019). Knockdown of the m6A results in an increase in total RNA and in the specific transcripts. These changes were also observed at the protein level using proteomics studies. We further analyse the effect m6A writer knockdown has on the half-life of specific mRNA that is predicted to be m6A enriched by the m6A writer.
These findings support the hypothesis that the m6A regulates the expression of specific genes by targeted degradation of mRNA, thus reducing translation. Further studies are needed to identify the mechanisms of targeted mRNA degradation.