Abstract
In Saccharomyces cerevisiae, telomere replication occurs in late S phase and is accompanied by dynamic remodeling of its protein components. Here, we show that MRX (Mre11-Rad50-Xrs2), an evolutionarily conserved protein complex involved in DNA double-strand break (DSB) repair, is recruited to the telomeres in late S phase. MRX is required for the late S phase-specific recruitment of ATR-like kinase Mec1 to the telomeres. Mec1, in turn, contributes to the assembly of the telomerase regulators Cdc13 and Est1 at the telomere ends. Our results provide a model for the hierarchical assembly of telomere-replication proteins in late S phase; this involves triggering by the loading of MRX onto the chromosome termini. The recruitment of DNA repair-related proteins to the telomeres at particular times in the cell cycle suggests that the normal terminus of a chromosome is recognized as a DSB during the course of replication.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Chromatin Immunoprecipitation
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DNA / genetics
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DNA Repair*
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DNA Replication*
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Endodeoxyribonucleases / genetics*
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Endodeoxyribonucleases / metabolism
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Exodeoxyribonucleases / genetics*
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Exodeoxyribonucleases / metabolism
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Intracellular Signaling Peptides and Proteins
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Phenotype
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Protein Serine-Threonine Kinases
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S Phase*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / genetics*
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Saccharomyces cerevisiae Proteins / metabolism
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Telomere / genetics*
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Telomere / metabolism
Substances
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DNA-Binding Proteins
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Intracellular Signaling Peptides and Proteins
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RAD50 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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XRS2 protein, S cerevisiae
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DNA
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MEC1 protein, S cerevisiae
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Protein Serine-Threonine Kinases
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Endodeoxyribonucleases
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Exodeoxyribonucleases
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MRE11 protein, S cerevisiae