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Photofootprinting of DNA triplexes
V I Lyamichev1, O N Voloshin, M D Frank-Kamenetskii
1Department of Biology, George Mason University, Fairfax, VA 22030.
Nucleic Acids Research
|April 11, 1991
Summary
This study uses photofootprinting to analyze DNA triplexes, revealing that DNA duplexes are protected from photodamage within triplex structures under various conditions.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- DNA triplexes are three-stranded nucleic acid structures with significant biological implications.
- Understanding triplex stability and formation is crucial for various molecular biology applications.
- Photodamage assays offer a method to probe DNA structural conformations.
Purpose of the Study:
- To investigate the formation and stability of intermolecular and intramolecular DNA triplexes.
- To utilize a photofootprinting assay to detect and characterize DNA triplexes.
- To examine the influence of pH, divalent cations, and specific sequences on triplex formation.
Main Methods:
- Employed a photofootprinting assay based on differential photodamage to DNA duplexes within triplexes.
- Studied triplex formation under varying pH conditions (acidic).
- Investigated the effects of divalent cations (Mg++, Zn++) and spermidine on triplex stability.
Main Results:
- The photofootprinting assay successfully detected PyPuPu (YRR) and PyPuPy (YRY) triplexes.
- Acidic pH facilitated the detection of d(C)n.d(G)n.d(C)n and d(CT)n.d(GA)n.d(CT)n triplexes.
- Divalent cations and spermidine stabilized specific triplexes, with cation type and DNA sequence influencing stabilization (e.g., Zn++ for d(CT)n.d(GA)n.d(GA)n, Mg++ for d(C)n.d(G)n.d(G)n).
Conclusions:
- The photofootprinting assay is effective for studying DNA triplexes under diverse conditions.
- DNA triplex formation and stability are modulated by pH, specific cations, and sequence composition.
- Differential protection against photodamage was observed in H-DNA and intramolecular CGG triplexes.