Deciphering the principles of the RNA editing code via large-scale systematic probing.

Area of Science:

• Molecular Biology
• RNA Biology
• Biochemistry

Background:

• Adenosine-to-inosine (A-to-I) editing is a widespread post-transcriptional modification catalyzed by ADAR1.
• Understanding ADAR1 substrate selection is crucial for its physiological, bioengineering, and therapeutic applications.
• Current knowledge of ADAR1 editing rules remains incomplete.

Purpose of the Study:

• To investigate the structural and sequence determinants of ADAR1 substrate selection.
• To elucidate the rules governing the formation and propagation of A-to-I editing sites.
• To develop a predictive model for RNA editing based on structural context.

Main Methods:

• Systematic probing of approximately 2,000 synthetic RNA constructs.
• Analysis of RNA structure and sequence context to identify editing determinants.
• Development of a recursive model for RNA editing propagation.

Main Results:

• Two key structural layers govern A-to-I editing site formation and propagation, independent of primary sequence.
• Editing is robustly induced at fixed intervals (35 bp upstream, 30 bp downstream) relative to structural disruptions.
• Editing is introduced symmetrically on opposite sites within double-stranded RNA structures.

Conclusions:

• A recursive model for RNA editing is proposed, where editing at one site influences subsequent editing.
• Structural alterations drive iterative editing site formation with fixed periodicity.
• This mechanism explains the propagation of editing along and across double-stranded RNA.