Abstract
Telomeric TG-rich repeats and their associated proteins protect the termini of eukaryotic chromosomes from end-to-end fusions. Associated with the cap structure at yeast telomeres is a subtelomeric domain of heterochromatin, containing the silent information regulator (SIR) complex. The Ku70/80 heterodimer (yKu) is associated both with the chromosome end and with subtelomeric chromatin. Surprisingly, both yKu and the chromatin-associated Rap1 and SIR proteins are released from telomeres in a RAD9-dependent response to DNA damage. yKu is recruited rapidly to double-strand cuts, while low levels of SIR proteins are detected near cleavage sites at later time points. Consistently, yKu- or SIR-deficient strains are hypersensitive to DNA-damaging agents. The release of yKu from telomeric chromatin may allow efficient scanning of the genome for DNA strand breaks.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Antigens, Nuclear*
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Bleomycin / pharmacology
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Cell Cycle Proteins / metabolism
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DNA Damage*
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DNA Helicases*
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DNA Repair*
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DNA-Binding Proteins / metabolism*
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Deoxyribonucleases, Type II Site-Specific / biosynthesis
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Dimerization
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Enzyme Induction
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Fungal Proteins / metabolism*
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GTP-Binding Proteins / metabolism
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Genotype
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Ku Autoantigen
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Nuclear Proteins / metabolism*
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Polymerase Chain Reaction
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Saccharomyces cerevisiae / cytology
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Saccharomyces cerevisiae / drug effects
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae Proteins*
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Silent Information Regulator Proteins, Saccharomyces cerevisiae*
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Telomere / genetics
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Telomere / physiology
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Transcription Factors / metabolism
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rap GTP-Binding Proteins
Substances
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Antigens, Nuclear
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Cell Cycle Proteins
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DNA-Binding Proteins
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Fungal Proteins
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Nuclear Proteins
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SIR4 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Silent Information Regulator Proteins, Saccharomyces cerevisiae
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Transcription Factors
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high affinity DNA-binding factor, S cerevisiae
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Bleomycin
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rad9 protein
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SCEI protein, S cerevisiae
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Deoxyribonucleases, Type II Site-Specific
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GTP-Binding Proteins
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DNA Helicases
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XRCC5 protein, human
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Xrcc6 protein, human
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rap GTP-Binding Proteins
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Ku Autoantigen