Editosome

Editosome is a multi-protein ribonucleoprotein complex that catalyzes RNA editing in the mitochondria of kinetoplastid protozoa, including species such as Trypanosoma and Leishmania. In these organisms, many mitochondrial transcripts undergo extensive uridine insertion and deletion, guided by small RNA templates known as guide RNAs (gRNAs). The editosome coordinates recognition of editing sites, cleavage of the RNA, insertion or deletion of uridines, and ligation of the RNA backbone to produce mature transcripts.

The core machinery, often referred to as the RNA Editing Core Complex (RECC), carries the catalytic activities required for editing. This typically includes endonucleases that cleave at editing sites, exonucleases that trim RNA ends, terminal uridylyl transferases that add uridines, and RNA ligases that seal the repaired transcripts. Additional subunits provide RNA binding, guide RNA interactions, and structural organization, enabling substrate recognition and processivity. The composition and abundance of editosome subunits can vary among species and developmental stages, reflecting different regulatory needs.

Editing proceeds through iterative cycles along many sites within a transcript, using the sequence information of gRNAs to specify insertions and deletions. The resulting edited transcripts are essential for the expression of mitochondrial genes, including components of the electron transport chain, and editing is often required for parasite viability in particular life stages.

Editosome research continues to illuminate its dynamic assembly, subunit interactions, and potential as a target for therapies against kinetoplastid infections.