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Single-Molecule Fluorescence Visualization of DNA Polymerase Dynamics at G-Quadruplexes
Published on: April 4, 2025
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Cockayne Syndrome B Protein Selectively Resolves and Interact with Intermolecular DNA G-Quadruplex Structures
Denise Liano1,2, Souroprobho Chowdhury1,2, Marco Di Antonio1,2,3
1Chemistry Department, Imperial College London, Molecular Science Research Hub, 82 Wood Lane, London W12 0BZ, United Kingdom.
Journal of the American Chemical Society
|December 2, 2021
Summary
Cockayne Syndrome B (CSB) protein selectively binds and resolves intermolecular G-quadruplexes (G4s) in rDNA. This interaction is crucial for maintaining cellular homeostasis and may impact premature aging phenotypes.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Guanine-rich DNA forms G-quadruplexes (G4s), which can be intramolecular or intermolecular.
- Research has primarily focused on intramolecular G4s due to the perceived low abundance of intermolecular G4s in genomic DNA.
Purpose of the Study:
- To identify endogenous proteins that interact with intermolecular G-quadruplexes.
- To investigate the functional role of such interactions in cellular processes.
Main Methods:
- Protein binding assays to determine affinity for different G4 structures.
- G4 resolution assays to assess protein activity.
- Immunostaining in cell lines with varying CSB levels.
- G4-specific antibody (BG4) staining in nucleoli.
Main Results:
- Cockayne Syndrome B (CSB) protein exhibits picomolar affinity for intermolecular G4s within rDNA, with minimal binding to intramolecular G4s.
- CSB selectively resolves intermolecular G4s over intramolecular ones.
- CSB depletion in cells leads to altered G4 staining in the nucleolus, which is restored by CSB expression.
Conclusions:
- CSB is the first identified endogenous protein with high selectivity for intermolecular G4s in rDNA.
- Intermolecular G4s form in rDNA and serve as a substrate for CSB.
- The CSB-intermolecular G4 interaction in rDNA is potentially linked to cellular homeostasis and aging phenotypes.
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