Mex67 paralogs mediate division of labor in trypanosome RNA processing and export [article]

Samson O Obado, Milana Stein, Eva Hegedusova, Wenzhu Zhang, Sebastian Hutchinson, Lucy Glover, Zdenek Paris, Brian T Chait, Mark C Field, Michael P Rout
2022 bioRxiv   pre-print
In opistokhonts (animals and fungi), mRNA export to the cytoplasm is mediated by the Mex67/Mtr2 (NXF1/NXT1) heterodimer via the nuclear pore complex (NPC). In contrast to most nucleocytoplasmic transport, mRNA export requires ATP-dependent remodeling machinery, and in animals and fungi is Ran-independent. While most eukaryotes possess one Mex67 gene, trypanosomes have three distinct Mex67 paralogs, while retaining a single Mtr2 gene. We show here that these paralogs, TbMex67, TbMex67b and
more » ... 7L, have differing and non-redundant roles in RNA export. Specifically, TbMex67 and TbMex67b retain a canonical role in mRNA export, albeit associating with specific mRNA cohorts, but in contrast, TbMex67L is primarily involved in ribosome biogenesis. Together with the association of all Mex67 paralogs with the Ran machinery, these findings indicate significant departures in RNA export mechanisms in these divergent organisms, with implications for evolutionary origins and diversity in control of gene expression.
doi:10.1101/2022.06.27.497849 fatcat:bd4aemrymjdivmirtdftqdb7hm