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Unusual behavior exhibited by multistranded guanine-rich DNA complexes
1Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Ontario, Canada.
Biopolymers
|April 16, 1998
Summary
Oligonucleotides with uninterrupted G-rich sequences form stable, multi-stranded complexes. Telomere-like sequences form different structures, with varying stability and strand numbers, influenced by methylation and magnesium ions.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- G-rich sequences in oligonucleotides can form complex structures.
- Telomere sequences have specific G-rich motifs.
Purpose of the Study:
- Compare structural properties of oligonucleotides with different G-rich 3'-end sequences.
- Investigate the impact of sequence variations on complex formation and stability.
Main Methods:
- Methylation protection and interference assays.
- Analysis of complex stoichiometry and thermal stability.
- Investigation of magnesium ion effects on complex formation.
Main Results:
- Uninterrupted G-rich sequences (d(T15G15), d(T15G12)) form stable, multi-stranded complexes via G-G interactions, with accessible guanines.
- Telomere-like sequences (d(T15G4T2G4)) form complexes with inaccessible guanines and different stoichiometry (1, 2, 4, or multiples of four strands).
- Magnesium ions stabilize high molecular weight complexes for uninterrupted G-rich sequences, but not for telomere-like sequences.
Conclusions:
- Oligonucleotide sequence at the 3'-end dictates structural properties and complex formation.
- Uninterrupted G-runs yield highly stable complexes, distinct from telomere-like structures.
- Sequence-dependent G-methylation accessibility influences supramolecular assembly and stability.