Abstract
Double-strand breaks (DSBs) are potentially lethal DNA lesions that can be repaired by either homologous recombination (HR) or nonhomologous end-joining (NHEJ). We show that DSBs induced by ionizing radiation (IR) are efficiently processed for HR and bound by Rfa1 during G1, while endonuclease-induced breaks are recognized by Rfa1 only after the cell enters S phase. This difference is dependent on the DNA end-binding Yku70/Yku80 complex. Cell-cycle regulation is also observed in the DNA damage checkpoint response. Specifically, the 9-1-1 complex is required in G1 cells to recruit the Ddc2 checkpoint protein to damaged DNA, while, upon entry into S phase, the cyclin-dependent kinase Cdc28 and the 9-1-1 complex both serve to recruit Ddc2 to foci. Together, these results demonstrate that the DNA repair machinery distinguishes between different types of damage in G1, which translates into different modes of checkpoint activation in G1 and S/G2 cells.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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CDC28 Protein Kinase, S cerevisiae / genetics
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CDC28 Protein Kinase, S cerevisiae / metabolism
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism
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DNA Breaks, Double-Stranded*
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DNA Damage*
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DNA Repair*
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DNA* / genetics
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DNA* / metabolism
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DNA* / radiation effects
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Deoxyribonucleases, Type II Site-Specific / metabolism
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Endodeoxyribonucleases / genetics
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Endodeoxyribonucleases / metabolism
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Endonucleases
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Exodeoxyribonucleases / genetics
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Exodeoxyribonucleases / metabolism
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G1 Phase / physiology*
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Genes, cdc
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Humans
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Phosphoproteins / genetics
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Phosphoproteins / metabolism
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Radiation, Ionizing
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Recombination, Genetic
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Replication Protein A
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S Phase / physiology
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Saccharomyces cerevisiae / cytology
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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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Transcription Factors / genetics
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Transcription Factors / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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Cell Cycle Proteins
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DNA-Binding Proteins
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Ddc1 protein, S cerevisiae
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LCD1 protein, S cerevisiae
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MEC3 protein, S cerevisiae
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Phosphoproteins
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RFA1 protein, S cerevisiae
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Recombinant Fusion Proteins
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Replication Protein A
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SAE2 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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YKU70 protein, S cerevisiae
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DNA
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CDC28 Protein Kinase, S cerevisiae
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Endodeoxyribonucleases
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Endonucleases
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Exodeoxyribonucleases
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MRE11 protein, S cerevisiae
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SCEI protein, S cerevisiae
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Deoxyribonucleases, Type II Site-Specific