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Non-complementary DNA helical structure induced by positive torsional stress
A V Vologodskii1, X Yang, N C Seeman
1Department of Chemistry, New York University, New York, NY 10003, USA.
Nucleic Acids Research
|April 29, 1998
Summary
Positive torsional stress induces a conformational transition in circular DNA cruciforms. This transition results in mispaired nucleotides while maintaining similar twist to paired DNA, as shown by gel electrophoresis.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- Circular DNA molecules can form complex structures like cruciforms.
- Torsional stress can influence DNA conformation and stability.
- Branched junctions in DNA can exhibit different mobilities under stress.
Purpose of the Study:
- To investigate the effect of positive torsional stress on synthetic circular DNA containing cruciforms.
- To analyze the conformational changes induced by ethidium binding in these DNA structures.
- To determine the structural properties of DNA cruciforms under torsional stress.
Main Methods:
- Induction of torsional stress using ethidium in low ionic strength buffer.
- Analysis of DNA conformational changes via gel electrophoresis.
- Comparison of electrophoretic mobility with control DNA molecules.
Main Results:
- Ethidium addition induced alterations in gel electrophoretic mobility of circular DNA cruciforms.
- A conformational transition occurred under positive torsional stress.
- The resulting structure featured mispaired nucleotides with interwound backbones.
Conclusions:
- The twist in the mispairing region of the transition product is similar to that of completely paired DNA species.
- Torsional stress can induce significant conformational changes in DNA cruciforms.
- Gel electrophoresis is a viable method for studying these stress-induced DNA transitions.