Abstract
In many organisms, telomere DNA consists of simple sequence repeat tracts that are required to protect the chromosome end. In the yeast Saccharomyces cerevisiae, tract maintenance requires two checkpoint kinases of the ATM family, Tel1p and Mec1p. Previous work has shown that Tel1p is recruited to functional telomeres with shorter repeat tracts to promote telomerase-mediated repeat addition, but the role of Mec1p is unknown. We found that Mec1p telomere association was detected as cells senesced when telomere function was compromised by extreme shortening due to either the loss of telomerase or the double-strand break binding protein Ku. Exonuclease I effects the removal of the 5' telomeric strand, and eliminating it prevented both senescence and Mec1p telomere association. Thus, in contrast to Tel1p, Mec1p associates with short, functionally compromised telomeres.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Cell Proliferation
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Exodeoxyribonucleases / genetics
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Exodeoxyribonucleases / metabolism
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism*
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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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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Saccharomyces cerevisiae Proteins
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high affinity DNA-binding factor, S cerevisiae
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MEC1 protein, S cerevisiae
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Protein Serine-Threonine Kinases
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TEL1 protein, S cerevisiae
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Exodeoxyribonucleases
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exodeoxyribonuclease I