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Updated: May 20, 2026
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Single-Molecule Fluorescence Visualization of DNA Polymerase Dynamics at G-Quadruplexes
Published on: April 4, 2025
d(TG(n)T) DNA sequences do not necessarily form tetramolecular G-quadruplexes
Laure Joly1, Frédéric Rosu, Valérie Gabelica
1Physical Chemistry and Mass Spectrometry Laboratory, Department of Chemistry, University of Liège, B-4000 Liège, Belgium.
Chemical Communications (Cambridge, England)
|July 17, 2012
Summary
DNA sequences with TG repeats typically form G-quadruplex structures. Contrary to expectations, longer G-tracts lead to smaller assemblies, forming trimers, dimers, and monomers, influenced by ion concentration.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- DNA sequences containing guanine (G) tracts are known to form G-quadruplex structures.
- The d(TG(n)T) motif is a specific type of G-rich sequence implicated in G-quadruplex formation.
- Tetramolecular G-quadruplexes are commonly hypothesized for certain G-rich DNA sequences.
Purpose of the Study:
- To investigate the actual G-quadruplex assembly structures formed by d(TG(n)T) DNA sequences.
- To determine how G-tract length influences the folding and assembly of these DNA sequences.
- To assess the role of ionic strength in the final G-quadruplex structure.
Main Methods:
- Utilized mass spectrometry to analyze the structures formed by d(TG(n)T) DNA sequences.
- Varied the G-tract length (n) in the DNA sequences.
- Adjusted ionic strength conditions during the experiments.
Main Results:
- Observed that d(TG(n)T) sequences predominantly form G-quadruplex trimers, dimers, and monomers.
- Found that increasing G-tract length favors smaller G-quadruplex assemblies (trimers, dimers, monomers).
- Demonstrated that ionic strength is a critical factor affecting the final G-quadruplex conformation.
Conclusions:
- The common belief that d(TG(n)T) sequences form tetramolecular G-quadruplexes is challenged.
- G-quadruplex assembly size is inversely correlated with G-tract length for these sequences.
- Environmental factors like ionic strength significantly modulate G-quadruplex structural outcomes.
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