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Stabilization of PyPuPu triplexes with bivalent cations.
M D Frank-Kamenetskii1, V A Malkov, O N Voloshin
1Institute of Molecular Genetics, Moscow, USSR.
Nucleic Acids Symposium Series
|January 1, 1991
Summary
Bivalent cations like zinc stabilize specific DNA triplexes (PyPuPu). Zinc ions facilitate the formation of arbitrary purine sequences into these stable DNA structures under neutral conditions.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- DNA triplexes are three-stranded nucleic acid structures.
- Their stability is influenced by factors like pH and cation concentration.
- Understanding triplex formation is crucial for applications in gene regulation and therapeutics.
Purpose of the Study:
- To investigate the formation of stable PyPuPu intermolecular DNA triplexes.
- To identify specific bivalent cations that stabilize these triplexes under neutral pH.
- To determine the influence of cations on different triplex sequences.
Main Methods:
- Utilized photo- and DMS footprinting assays.
- Tested a range of bivalent cations (Mg, Ca, Mn, Co, Ni, Cu, Zn, Cd, Ba).
- Analyzed the stabilization of d(C)n.d(G)n.d(G)n and d(TC)n.d(GA)n.d(AG)n triplexes.
Main Results:
- Zinc ions (Zn++) stabilized both d(C)n.d(G)n.d(G)n and d(TC)n.d(GA)n.d(AG)n triplexes.
- Magnesium ions (Mg++) stabilized d(C)n.d(G)n.d(G)n but not d(TC)n.d(GA)n.d(AG)n triplexes.
- Arbitrary purine sequences formed PyPuPu triplexes with Zn++.
Conclusions:
- Specific bivalent cations, particularly Zn++, are key for forming stable PyPuPu DNA triplexes.
- The purine third strand in these triplexes is antiparallel to the purine strand within the duplex.
- Findings provide insights into DNA structural dynamics and cation interactions for potential biotechnological applications.