Related Experiment Videos
Structures of bulged three-way DNA junctions
J B Welch1, D R Duckett, D M Lilley
1Department of Biochemistry, The University, Dundee, UK.
Nucleic Acids Research
|September 25, 1993
Summary
Unpaired bases in three-way DNA junctions influence their structure, causing ion-dependent folding. These junctions adopt distinct conformations with potential coaxial stacking, affecting DNA stability.
Area of Science:
- Molecular Biology
- Biophysics
- Structural Biology
Background:
- Three-way DNA junctions are crucial structural motifs in nucleic acids.
- Understanding their conformational dynamics is key to comprehending DNA function and stability.
Purpose of the Study:
- To investigate the structural consequences of incorporating unpaired bases into three-way DNA junctions.
- To explore the role of metal ions in modulating junction conformation and stability.
Main Methods:
- Polyacrylamide gel electrophoresis was employed to analyze junction conformation.
- The study systematically varied junction sequences and the presence of metal ions (magnesium (II) and hexamine cobalt (III)).
Main Results:
- In the absence of metal ions, junctions adopted extended structures.
- Addition of magnesium (II) or hexamine cobalt (III) ions induced ion-dependent folding transitions in some junctions.
- Unpaired bases promoted a distinct structure with a smaller inter-arm angle and protection against osmium addition.
Conclusions:
- The conformation of three-way DNA junctions is sensitive to both unpaired bases and metal ion concentration.
- A model of coaxial stacking of helical arms is proposed, influenced by unpaired bases and magnesium ions.
- These findings provide insights into DNA structural plasticity and ion-mediated stabilization.