Abstract
SMC proteins constitute the core members of the Smc5/6, cohesin and condensin complexes. We demonstrate that Smc5/6 is present at telomeres throughout the cell cycle and its association with chromosome ends is dependent on Nse3, a subcomponent of the complex. Cells harboring a temperature sensitive mutant, nse3-1, are defective in Smc5/6 localization to telomeres and have slightly shorter telomeres. Nse3 interacts physically and genetically with two Rap1-binding factors, Rif2 and Sir4. Reduction in telomere-associated Smc5/6 leads to defects in telomere clustering, dispersion of the silencing factor, Sir4, and a loss in transcriptional repression for sub-telomeric genes and non-coding telomeric repeat-containing RNA (TERRA). SIR4 recovery at telomeres is reduced in cells lacking Smc5/6 functionality and vice versa. However, nse3-1/ sir4 Δ double mutants show additive defects for telomere shortening and TPE indicating the contribution of Smc5/6 to telomere homeostasis is only in partial overlap with SIR factor silencing. These findings support a role for Smc5/6 in telomere maintenance that is separate from its canonical role(s) in HR-mediated events during replication and telomere elongation.
MeSH terms
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Adenosine Triphosphatases / genetics
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Adenosine Triphosphatases / metabolism
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Cell Cycle Proteins / genetics*
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Cell Cycle Proteins / metabolism
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Chromosomal Proteins, Non-Histone / genetics
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Chromosomal Proteins, Non-Histone / metabolism
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Chromosomes / genetics
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Cohesins
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DNA Replication / genetics
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Multiprotein Complexes / genetics
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Multiprotein Complexes / metabolism
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Mutation
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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 / genetics
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Telomere / genetics*
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Telomere-Binding Proteins / genetics
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Transcription, Genetic*
Substances
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Cell Cycle Proteins
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Chromosomal Proteins, Non-Histone
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DNA-Binding Proteins
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Multiprotein Complexes
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RIF2 protein, S cerevisiae
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SIR4 protein, S cerevisiae
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SMC5 protein, S cerevisiae
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SMC6 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Silent Information Regulator Proteins, Saccharomyces cerevisiae
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Telomere-Binding Proteins
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condensin complexes
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Adenosine Triphosphatases