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Bent helix formation between RNA hairpins with complementary loops
J P Marino1, R S Gregorian, G Csankovszki
1Department of Chemistry, Yale University, New Haven, CT 06511, USA.
Science (New York, N.Y.)
|June 9, 1995
Summary
The ColE1 plasmid replication is regulated by RNA I and RNA II. Their interaction forms a complex, stabilized by a bent helix and the Rom protein, influencing plasmid stability.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- ColE1 plasmid replication relies on antisense RNA regulators, RNA I and RNA II.
- The initial interaction involves complementary loops within these RNA transcripts.
- The Rom protein, encoded by ColE1, modulates this replication process.
Purpose of the Study:
- To characterize the structural complex formed between complementary RNA loops.
- To investigate the role of RNA secondary structures in antisense regulation.
- To understand the impact of the Rom protein on RNA-protein and RNA-RNA interactions.
Main Methods:
- Multidimensional heteronuclear magnetic resonance (2D/3D NMR) spectroscopy.
- Gel electrophoresis to analyze RNA structures and complexes.
- Utilizing model RNA hairpins with seven-nucleotide complementary loops.
Main Results:
- A seven base-pair helix is formed between complementary RNA loops.
- Continuous helical stacking occurs on the 3' side of the helical stems.
- A sharp bend in the loop-loop helix narrows the major groove, facilitating hairpin loop closure.
- The Rom protein binding further enhances this structural bend.
Conclusions:
- The transient complex formation is structurally defined by a bent loop-loop helix.
- The observed structural features, including the bend and major groove narrowing, are crucial for RNA-RNA interaction and regulation.
- Rom protein binding stabilizes the regulatory complex through conformational changes.