Abstract
Budding yeast telomeres are reversibly bound at the nuclear envelope through two partially redundant pathways that involve the Sir2/3/4 silencing complex and the Yku70/80 heterodimer. To better understand how this is regulated, we studied the role of SUMOylation in telomere anchoring. We find that the PIAS-like SUMO E3 ligase Siz2 sumoylates both Yku70/80 and Sir4 in vivo and promotes telomere anchoring to the nuclear envelope. Remarkably, loss of Siz2 also provokes telomere extension in a telomerase-dependent manner that is epistatic with loss of the helicase Pif1. Consistent with our previously documented role for telomerase in anchorage, normal telomere anchoring in siz2 Δ is restored by PIF1 deletion. By live-cell imaging of a critically short telomere, we show that telomeres shift away from the nuclear envelope when elongating. We propose that SUMO-dependent association with the nuclear periphery restrains bound telomerase, whereas active elongation correlates with telomere release.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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DNA Helicases / genetics
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DNA Helicases / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Microscopy, Fluorescence
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Mutation
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Nuclear Envelope / enzymology*
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Protein Processing, Post-Translational
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae / enzymology*
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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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Silent Information Regulator Proteins, Saccharomyces cerevisiae / genetics
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Silent Information Regulator Proteins, Saccharomyces cerevisiae / metabolism
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Sumoylation
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Telomerase / metabolism*
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Telomere / enzymology*
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Time Factors
Substances
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DNA-Binding Proteins
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Recombinant Fusion 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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Siz2 protein, S cerevisiae
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YKU70 protein, S cerevisiae
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YKU80 protein, S cerevisiae
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Telomerase
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PIF1 protein, S cerevisiae
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DNA Helicases