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Author Spotlight: Advanced Single-Molecule Techniques for Investigating Telomeric Protein-DNA Interactions
Published on: August 30, 2024
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A sharp Pif1-dependent threshold separates DNA double-strand breaks from critically short telomeres.
Jonathan Strecker1,2, Sonia Stinus3, Mariana Pliego Caballero3
1Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.
Elife
|August 23, 2017
Summary
DNA double-strand breaks (DSBs) and short telomeres have different fates. A minimum of 34 base pairs of telomeric repeats signal DNA ends to avoid Pif1 helicase, allowing telomerase extension and distinguishing telomeres from DSBs.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- DNA double-strand breaks (DSBs) and short telomeres share structural similarities but have distinct cellular outcomes.
- Cells must differentiate between DSBs requiring repair and telomeres needing telomerase extension.
Purpose of the Study:
- To investigate the critical length threshold that distinguishes telomeres from DSBs in Saccharomyces cerevisiae.
- To understand the role of Pif1 helicase and Cdc13 in regulating telomere length and end fate.
Main Methods:
- Utilizing Pif1 helicase as a sensor for DNA end recognition.
- Experimentally manipulating telomeric repeat lengths (TG1-3)n to determine Pif1 insensitivity.
- Analyzing telomerase extension efficiency at different telomere lengths.
Main Results:
- A transition point of 34 base pairs (bp) of telomeric repeats was identified, rendering DNA ends insensitive to Pif1 helicase.
- Telomeres shorter than approximately 40 bp showed inefficient telomerase extension.
- Cdc13 protein is proposed to confer Pif1 insensitivity to telomeric ends with at least 34 bp.
Conclusions:
- The Pif1 activity threshold, defined by ~34 bp of telomeric repeats, acts as a critical determinant between DSBs and functional telomeres.
- This length-dependent mechanism ensures proper telomere maintenance and prevents aberrant processing of chromosome ends.
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