Evolutionary Conservation and Diversification of the Translation Initiation Apparatus in Trypanosomatids

الملخص EN

Trypanosomatids are ancient eukaryotic parasites that migrate between insect vectors and mammalian hosts, causing a range of diseases in humans and domestic animals.

Trypanosomatids feature a multitude of unusual molecular features, including polycistronic transcription and subsequent processing by trans-splicing and polyadenylation.

Regulation of protein coding genes is posttranscriptional and thus, translation regulation is fundamental for activating the developmental program of gene expression.

The spliced-leader RNA is attached to all mRNAs.

It contains an unusual hypermethylated cap-4 structure in its 5′ end.

The cap-binding complex, eIF4F, has gone through evolutionary changes in accordance with the requirement to bind cap-4.

The eIF4F components in trypanosomatids are highly diverged from their orthologs in higher eukaryotes, and their potential functions are discussed.

The cap-binding activity in all eukaryotes is a target for regulation and plays a similar role in trypanosomatids.

Recent studies revealed a novel eIF4E-interacting protein, involved in directing stage-specific and stress-induced translation pathways.

Translation regulation during stress also follows unusual regulatory cues, as the increased translation of Hsp83 following heat stress is driven by a defined element in the 3′ UTR, unlike higher eukaryotes.

Overall, the environmental switches experienced by trypanosomatids during their life cycle seem to affect their translational machinery in unique ways.