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Updated: May 15, 2025
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Chemical Dimerization-Induced Protein Condensates on Telomeres
Published on: April 12, 2021
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Dimerization of Cdc13 is essential for dynamic DNA exchange on telomeric DNA
David G Nickens1, Spencer J Gray1, Robert H Simmons1
1Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA.
Biorxiv : the Preprint Server for Biology
|April 8, 2025
Summary
Cdc13, a single-stranded DNA binding protein, is crucial for telomere protection. We found that Cdc13 dimerization is essential for its dynamic DNA exchange, a process vital for maintaining telomere length homeostasis in yeast.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Single-stranded DNA binding proteins (ssBPs) protect eukaryotic telomeres.
- Cdc13 is an essential ssBP in *Saccharomyces cerevisiae*, regulating telomere length and end protection, often within the CST complex.
- Cdc13 exhibits high affinity and slow off-rate for telomeric ssDNA, yet dynamically exchanges on telomeres.
Purpose of the Study:
- To investigate the role of Cdc13 dimerization in its dynamic DNA exchange (DDE) process.
- To characterize the dimerization mutant Cdc13-L91R and its effect on ssDNA binding and exchange.
Main Methods:
- Mass photometry to assess Cdc13 dimerization.
- Gel-based assays to evaluate ssDNA exchange.
- Biolayer interferometry to analyze ssDNA binding kinetics.
Main Results:
- The Cdc13-L91R mutant protein failed to dimerize in solution, even with ssDNA present.
- Cdc13-L91R exhibited a complete loss of ssDNA exchange capability compared to wild-type Cdc13.
- ssDNA binding kinetics were not significantly altered in the dimerization mutant.
Conclusions:
- Cdc13 dimerization is indispensable for dynamic DNA exchange on telomeric ssDNA.
- This finding provides insights into the mechanism of telomere maintenance and regulation by Cdc13 *in vivo*.
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