RNA quaternary structure and global symmetry

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Proteins commonly form symmetric complexes.
• Complex RNAs were traditionally viewed as asymmetric monomers.
• Recent structural data challenge this paradigm, revealing RNA global symmetry.

Purpose of the Study:

• To survey and highlight known examples of global RNA symmetry.
• To investigate the functional implications of RNA symmetry.
• To present RNA symmetry as a significant structural principle.

Main Methods:

• Literature survey of structural studies on biological RNAs.
• Analysis of crystal structures revealing global symmetry.
• Comparative analysis of symmetric and asymmetric RNA structures.

Main Results:

• Identified true quaternary symmetry in bacteriophage ϕ29 prohead RNA (pRNA).
• Revealed internal pseudosymmetry in flavin mononucleotide (FMN), glycine, and cyclic di-AMP (c-di-AMP) riboswitches.
• Demonstrated that global symmetry stabilizes RNA folds and ligand binding.

Conclusions:

• Global RNA symmetry is a recurring structural motif.
• Symmetry plays key roles in RNA folding, ligand coordination, and interactions with binding partners.
• RNA symmetry facilitates association with symmetric protein partners.