Trypanosome RNAEditing Substrate Binding Complex integrity and function depends on the upstream action of RESC10

Area of Science:

• Molecular Biology
• Genetics
• Parasitology

Background:

• Kinetoplastids, like Trypanosoma brucei, exhibit unique mitochondrial mRNA editing via uridine insertion/deletion.
• This process is guided by gRNAs and catalyzed by RNA Editing Core Complexes (RECCs).
• The RNA Editing Substrate Binding Complex (RESC) orchestrates interactions between RECC, gRNA, and mRNA, comprising GRBC and REMC components.

Purpose of the Study:

• To investigate the role of RESC10, an essential RNA binding protein, within the RESC complex.
• To elucidate the impact of RESC10 on mitochondrial mRNA editing in Trypanosoma brucei.
• To understand RESC10's specific functions in editing initiation and progression.

Main Methods:

• RNA interference (RNAi) to deplete RESC10 in Trypanosoma brucei.
• Analysis of RESC complex organization and protein-protein interactions.
• High-resolution analysis of mitochondrial RNA editing progression.
• Assessment of mRNA association with GRBC and REMC components.

Main Results:

• RESC10 is essential and interacts with RESC proteins, though minimally with RESC13.
• RESC10 depletion causes RESC disorganization, disrupts GRBC interactions, and alters mRNA localization.
• RESC10 depletion differentially affects editing: it impacts progression in RPS12 mRNA and initiation in other mRNAs.
• Editing pauses in RESC10-depleted cells correlate with sites in knockdowns of other RESC proteins, suggesting RESC10 acts upstream.

Conclusions:

• RESC10 is a crucial, low-abundance component of the RESC complex, essential for mitochondrial mRNA editing.
• RESC10 plays distinct roles in editing initiation and progression, potentially coordinating transitions between different RECC activities.
• The findings highlight RESC10's upstream function and the dynamic nature of RESC in facilitating editing.