Abundant mRNA m 1 A modification in dinoflagellates: a new layer of gene regulation.

Dinoflagellates, a class of unicellular eukaryotic phytoplankton, exhibit minimal transcriptional regulation, representing a unique model for exploring gene expression. The biosynthesis, distribution, regulation, and function of mRNA N1-methyladenosine (m ¹ A) remain controversial due to its limited presence in typical eukaryotic mRNA. This study provides a comprehensive map of m ¹ A in dinoflagellate mRNA and shows that m ¹ A, rather than N6-methyladenosine (m ⁶ A), is the most prevalent internal mRNA modification in various dinoflagellate species, with an asymmetric distribution along mature transcripts. In Amphidinium carterae, we identify 6549 m ¹ A sites characterized by a non-tRNA T-loop-like sequence motif within the transcripts of 3196 genes, many of which are involved in regulating carbon and nitrogen metabolism. Enriched within 3'UTRs, dinoflagellate mRNA m ¹ A levels negatively correlate with translation efficiency. Nitrogen depletion further decreases mRNA m ¹ A levels. Our data suggest that distinctive patterns of m ¹ A modification might influence the expression of metabolism-related genes through translational control.
(© 2024. The Author(s).)