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Updated: Jun 25, 2026

Analyzing Telomeric Protein-DNA Interactions Using Single-Molecule Magnetic Tweezers
Published on: August 30, 2024
Rif1 and rif2 inhibit localization of tel1 to DNA ends
Yukinori Hirano1, Kenzo Fukunaga, Katsunori Sugimoto
1Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA.
Abstract:
Chromosome ends, known as telomeres, have to be distinguished from DNA double-strand breaks (DSBs) that activate the DNA-damage checkpoint. In budding yeast, the ATM homolog Tel1 associates preferentially with short telomeres and promotes telomere addition. Here, we show that the telomeric proteins Rif1 and Rif2 attenuate Tel1 recruitment to DNA ends through distinct mechanisms. Both Rif1 and Rif2 inhibit the localization of Tel1, but not the Mre11-Rad50-Xrs2 (MRX) complex, to adjacent DNA ends. Rif1 function is weaker at short telomeric repeats compared with Rif2 function and is partly dependent on Rif2. Rif2 competes with Tel1 for binding to the C terminus of Xrs2. Once Tel1 is delocalized, MRX does not associate efficiently with Rap1-covered DNA ends. These results reveal a mechanism by which telomeric DNA sequences mask DNA ends from Tel1 recognition for the regulation of telomere length.
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