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A sharp Pif1-dependent threshold separates DNA double-strand breaks from critically short telomeres

Strecker, J., Stinus, S., Caballero, M. P., Szilard, R. K., Chang, M. & Durocher, D. 3-Aug-2017 In : eLife. 6, 59 p.

Research output: Scientific - peer-reviewArticle

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DOI

DNA double-strand breaks (DSBs) and short telomeres are structurally similar, yet have diametrically opposed fates. Cells must repair DSBs while blocking the action of telomerase on these ends. Short telomeres must avoid recognition by the DNA damage response while promoting telomerase recruitment. In Saccharomyces cerevisiae, the Pif1 helicase, a telomerase inhibitor, lies at the interface of these end-fate decisions. Using Pif1 as a sensor, we uncover a transition point in which 34 bp of telomeric (TG(1-3))(n) repeat sequence renders a DNA end insensitive to Pif1 action, thereby enabling extension by telomerase. A similar transition point exists at natural chromosome ends, where telomeres shorter than similar to 40 bp are inefficiently extended by telomerase. This phenomenon is not due to known Pif1 modifications and we instead propose that Cdc13 renders TG(34+) ends insensitive to Pif1 action. We contend that the observed threshold of Pif1 activity defines a dividing line between DSBs and telomeres.

Original languageEnglish
Number of pages59
JournaleLife
Volume6
StatePublished - 3-Aug-2017

    Keywords

  • SACCHAROMYCES-CEREVISIAE TELOMERES, LENGTH REGULATION, REPEAT DIVERGENCE, CHROMOSOME ENDS, CDC13 PROTEIN, IN-VIVO, YEAST, BINDING, ELONGATION, SEQUENCES

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