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Bulge-induced bends in RNA: quantification by transient electric birefringence
1Department of Biochemistry, Biophysics and Genetics, University of Colorado Health Sciences Center, Denver, USA.
Journal of Molecular Biology
|March 31, 1995
Summary
RNA bulges are common structural elements. This study measured bulge-induced bending in RNA using transient electric birefringence (TEB), revealing sequence and ion-dependent structural transitions.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- RNA bulges are prevalent non-helical structures crucial for RNA tertiary structure.
- Understanding RNA bulge conformation and flexibility is key to deciphering RNA folding rules.
Purpose of the Study:
- To quantify the bending induced by RNA bulges of varying sizes and compositions.
- To investigate the influence of sequence and magnesium ions (Mg2+) on bulge-induced bending.
Main Methods:
- Transient electric birefringence (TEB) was employed to measure bend angles in RNA duplexes with central bulges.
- Electrophoretic mobility was used to correlate with bend angles.
Main Results:
- Bulge angles ranged from 7 to 93 degrees, increasing with bulge size (n=1-6).
- Angle increments per nucleotide varied with bulge size and were affected by Mg2+ presence, particularly for U-rich bulges.
- A strong correlation was found between measured bend angles and reduced electrophoretic mobility.
Conclusions:
- RNA bulge structure exhibits sequence and counterion-dependent transitions.
- A semi-empirical relationship between bend angle and electrophoretic mobility was established for estimating bend angles.