Exploring GNRA tetraloop-like motifs in nucleic acid 3D structures

Area of Science:

• * RNA structure and bioinformatics
• * Molecular biology
• * Structural biology

Background:

• * Structured nucleic acids are crucial for molecular mechanisms and have applications in medicine and biotechnology.
• * Tetraloop motifs like UNCG and GNRA are stable RNA building blocks involved in molecular recognition.
• * The GNRA tetraloop motif interacts with RNA receptors and proteins, but GNRA-like conformations in non-tetraloop strands are not well-characterized.

Purpose of the Study:

• * To conduct a comprehensive survey of GNRA tetraloop-like motifs in known 3D nucleic acid structures.
• * To explore the diversity of these motifs based on isostericity, irrespective of sequence, loop type, or topology.
• * To understand how these motifs adapt to different structural contexts and interactions.

Main Methods:

• * Systematic survey of existing 3D nucleic acid structures.
• * Analysis based on isosteric similarity to the GNRA tetraloop motif.
• * Examination of sequence, loop type, backbone topology, and interaction partners.

Main Results:

• * Identification of twelve recurrent backbone topology variants of GNRA tetraloop-like motifs.
• * Discovery of five two-strand and six three-strand variants.
• * Observation of four distinct pentaloop variants, with three interacting with proteins.

Conclusions:

• * GNRA-like motifs exhibit remarkable versatility, adapting to various backbone contexts.
• * These motifs can modulate intermolecular interactions, offering potential for RNA design.
• * The findings expand the understanding of RNA structural diversity and functional potential.