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Analyzing Telomeric Protein-DNA Interactions Using Single-Molecule Magnetic Tweezers
Published on: August 30, 2024
Rap1 binds single-stranded DNA at telomeric double- and single-stranded junctions and competes with Cdc13 protein
Cecilia Gustafsson1, Jenny Rhodin Edsö, Marita Cohn
1Department of Biology, Genetics Group, Lund University, SE-223 62 Lund, Sweden.
The Journal of Biological Chemistry
|November 15, 2011
Summary
Saccharomyces castellii Rap1 and Cdc13 proteins bind to telomere DNA junctions. Rap1 exhibits dual binding modes, switching between sequence-specific and non-specific interactions to protect chromosome ends.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Eukaryotic chromosome ends (telomeres) are protected by specialized chromatin structures.
- Rap1 and Cdc13 are crucial for telomere chromatin formation in budding yeast, binding double-stranded and single-stranded DNA, respectively.
Purpose of the Study:
- To analyze the binding properties of Saccharomyces castellii Rap1 and Cdc13 at the double-stranded/single-stranded (ds-ss) DNA junction of telomeres.
- To determine optimal DNA configurations for simultaneous Rap1 and Cdc13 binding.
Main Methods:
- Analysis of Rap1 and Cdc13 binding to partially single-stranded oligonucleotides mimicking telomeric ds-ss junctions.
- Determination of optimal and minimal DNA structures for simultaneous protein binding.
Main Results:
- Rap1 can bind to partially single-stranded sites spanning the ds-ss junction, utilizing a sequence-specific interaction with a double-stranded hemi-site and a sequence-independent interaction with the single-stranded overhang.
- Rap1 demonstrates a switchable binding mode between sequence-specific and non-specific interactions at a single hemi-site.
- Rap1 and Cdc13 compete for binding when their respective sites at the ds-ss junction partially overlap.
Conclusions:
- Rap1 and Cdc13 cooperate to ensure the protection of both 3' and 5' DNA ends at telomeres.
- These findings provide insights into telomere end protection mechanisms mediated by Rap1 and Cdc13.
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