DRBD18 acts as a transcript-specific RNA editing auxiliary factor in Trypanosoma brucei

Area of Science:

• Mitochondrial gene expression
• Post-transcriptional modification
• Kinetoplastid biology

Background:

• Uridine insertion/deletion (U-indel) RNA editing is vital for generating mature mitochondrial mRNAs in kinetoplastids.
• Accessory RNA-binding proteins (RBPs) play transcript-specific roles in modulating this RNA editing process.
• DRBD18, a known RBP, was investigated for its potential role in mitochondrial RNA editing due to observed interactions with RESC factors.

Purpose of the Study:

• To investigate the role of DRBD18 in mitochondrial U-indel RNA editing in *Trypanosoma brucei*.
• To determine if DRBD18 directly interacts with RNA editing core complex (RESC) factors.
• To elucidate the impact of DRBD18's arginine methylation status on its mitochondrial function.

Main Methods:

• RNA interference (RNAi) for DRBD18 depletion and overexpression in procyclic *T. brucei*.
• Quantitative reverse transcription PCR (qRT-PCR) to measure edited transcript levels.
• RNA immunoprecipitation (RIP) followed by qRT-PCR to assess direct RNA binding.

Main Results:

• DRBD18 specifically and sensitively interacts with multiple RESC factors.
• Depletion of DRBD18 significantly reduced edited A6 and COIII mRNA levels, while overexpression increased them.
• DRBD18 directly participates in the editing of A6 and COIII mRNAs, with its hypomethylated form being essential.

Conclusions:

• DRBD18 is a novel auxiliary factor directly involved in mitochondrial RNA editing of specific mRNAs (A6, COIII) in *T. brucei*.
• The function of DRBD18 in RNA editing is modulated by its arginine methylation status.
• This study reports the first mitochondrial function for DRBD18.