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Conformational polymorphism in G-tetraplex structures: strand reversal by base flipover or sugar flipover
Nucleic Acids Research
|April 25, 1993
Summary
Guanine-rich sequences form G-quadruplexes with varied structures. A parallel, all-anti conformation is favored for short G-stretches, while antiparallel structures exhibit alternating syn-anti conformations.
Area of Science:
- Biochemistry
- Structural Biology
- Computational Chemistry
Background:
- Guanine-rich sequences can form G-quadruplexes, four-stranded DNA structures stabilized by Hoogsteen hydrogen-bonded guanine tetrads.
- These G-quadruplexes exhibit diverse strand orientations and glycosidic bond conformations.
Purpose of the Study:
- To investigate various possible conformations of guanines within a strand and their orientations in G-quadruplex structures.
- To provide a theoretical basis for observed structural features in G-quadruplexes.
Main Methods:
- Detailed molecular model building.
- Molecular mechanics calculations.
Main Results:
- A parallel, all-anti guanine conformation is favored for oligo G stretches.
- Alternating syn-anti guanine arrangements occur in folded-back, antiparallel G-quadruplex structures.
- Molecular mechanics elucidated stabilizing interactions and the effect of counterions on groove width.
Conclusions:
- The study provides a theoretical rationale for structural variations in G-quadruplexes, including glycosidic conformation and base stacking.
- Different strand orientations lead to distinct structural features.
- Counterion screening significantly impacts G-quadruplex groove dimensions.
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