Dimerization of ADAR2 is mediated by the double-stranded RNA binding domain

Area of Science:

• Molecular Biology
• RNA Biology
• Biochemistry

Background:

• Adenosine deaminases acting on RNA (ADARs) modify specific messenger RNAs (mRNAs) by converting adenosine to inosine.
• ADAR enzymes contain double-stranded RNA binding motifs (DRBMs) crucial for their function.
• RNA editing, particularly at the GluR2 Q/R site, is vital for neuronal function.

Purpose of the Study:

• To investigate the role of DRBMs in ADAR2 enzyme dimerization and RNA editing.
• To determine the specific functions of individual DRBMs within ADAR2.
• To elucidate the mechanism of ADAR2-mediated RNA editing at the GluR2 Q/R site.

Main Methods:

• In vitro and in vivo biochemical assays.
• Bioluminescence resonance energy transfer (BRET) for studying protein-protein interactions in living cells.
• Site-directed mutagenesis of DRBMs in rat ADAR2.

Main Results:

• ADAR2 DRBMs are necessary and sufficient for enzyme dimerization.
• ADAR2 forms dimers in mammalian cells, with DRBM1 influencing dimerization affinity.
• A functional DRBM2 is essential for efficient editing at the GluR2 Q/R site.
• DRBM1 and DRBM2 exhibit differential roles in dimerization and RNA editing.

Conclusions:

• ADAR2 DRBMs play distinct roles in enzyme dimerization and substrate RNA editing.
• The findings support a model where specific DRBMs mediate different steps in the RNA editing process.
• Understanding ADAR2 function provides insights into RNA sequence diversification and its biological implications.