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A collapsed state functions to self-chaperone RNA folding into a native ribonucleoprotein complex.
1Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
Nature Structural Biology
|February 15, 2001
Summary
Large RNAs like bI5 intron RNA use collapsed states to self-chaperone folding, preventing premature protein cofactor binding. This mechanism ensures proper assembly of complex RNA-protein machines.
Area of Science:
- Structural Biology
- Molecular Biology
- RNA Folding
Background:
- Large RNAs require protein cofactors for their active, native structures.
- The bI5 group I intron RNA exists in multiple conformational states (expanded, collapsed, native) influenced by Mg(2+) concentration.
Purpose of the Study:
- To investigate the role of RNA conformational states in protein cofactor interaction and folding.
- To understand the self-chaperoning mechanism of bI5 RNA folding.
Main Methods:
- Manipulation of RNA states using varying Mg(2+) concentrations.
- Hydroxyl radical footprinting to map RNA-protein interactions.
- Functional splicing experiments to assess complex productivity.
Main Results:
- bI5 RNA rapidly folds into a non-native collapsed state under near-physiological conditions.
- The CBP2 protein cofactor facilitates the transition from the collapsed to the native state.
- CBP2 binding to the expanded RNA state leads to non-native interactions and kinetically trapped complexes.
Conclusions:
- The collapsed state acts as a self-chaperone, preventing premature CBP2 binding and ensuring proper RNA folding.
- This self-chaperoning mechanism is crucial for preventing misassembly of large RNA-protein complexes in cells.