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Conformational adaptation of UNCG loops upon crowding
Mélanie Meyer1, Hélène Walbott2, Vincent Oliéric3
1PPRS, 68000 Colmar, France.
RNA (New York, N.Y.)
|August 21, 2019
Summary
RNA tetraloops, like GNRA and UNCG, can change their structure based on their environment. Highly packed conditions can cause Z-turn loops to adopt alternative conformations, influencing RNA
Area of Science:
- * Structural biology
- * Molecular biology
- * RNA structure and function
Background:
- * RNA molecules feature helical structures capped by loop motifs.
- * GNRA and UNCG tetraloops are prevalent and crucial RNA structural motifs.
- * These tetraloops can adopt non-canonical tertiary folds, including U-turns and Z-turns.
Purpose of the Study:
- * To investigate the conformational plasticity of UUCG tetraloops.
- * To understand how the structural environment influences tetraloop conformation.
- * To explore the biological implications of alternative tetraloop folds.
Main Methods:
- * Analysis of crystallographic data from lariat-capping (LC) ribozyme and group II intron ribozyme.
- * Examination of RNA structures in the Protein Data Bank (PDB).
- * Comparative analysis of tetraloop conformations under varying crystal packing constraints.
Main Results:
- * UUCG tetraloops can adopt distinct conformations, including the canonical Z-turn, depending on environmental constraints.
- * High molecular packing induces a
- squashed
- conformation by distorting the sugar-phosphate backbone.
- * This altered conformation involves base expulsion and interaction with adjacent helix base pairs.
- * Similar deformed loops were observed in the ribosome and dsRNA-RNase III complexes.
Conclusions:
- * Z-turn loops exhibit conformational flexibility influenced by molecular packing.
- * Beyond stabilizing RNA folding, Z-turn loops may mediate tertiary interactions in crowded biological environments.
- * This conformational adaptability is crucial for RNA's three-dimensional structure and function.
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