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Single strands, triple strands, and kinks in H-DNA
1Department of Physiological Chemistry, University of Wisconsin-Madison 53706.
Science (New York, N.Y.)
|September 30, 1988
Summary
DNA's H-conformation, a structure with triple-stranded and single-stranded regions, is stabilized by supercoiling and pH. This conformation introduces a flexible kink in DNA, forming hinged-DNA.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- DNA can adopt non-canonical structures beyond the B-form.
- The H-DNA conformation involves triple-stranded and single-stranded regions.
Purpose of the Study:
- To investigate the structural characteristics of H-DNA.
- To elucidate the factors influencing H-DNA stability.
- To propose a structural model for H-DNA.
Main Methods:
- Analysis of a naturally occurring (dT-dC)18:(dA-dG)18 repeat.
- Investigating DNA conformation under varying pH and supercoiling conditions.
Main Results:
- H-DNA contains single-stranded nucleotides within the TC18 and AG18 repeats.
- H-DNA stability is dependent on pH and negative supercoiling levels.
- A novel J-DNA conformation was observed at mildly alkaline pH.
- H-DNA introduces a sharp, flexible kink into the DNA molecule.
Conclusions:
- H-DNA is a stable structure comprising triple-stranded and single-stranded regions.
- pH and supercoiling are critical for H-DNA formation and stability.
- The proposed H-DNA model explains its structural features and kink formation, leading to hinged-DNA.