Abstract
In wild-type budding yeast strains, the proteins encoded by SIR3, SIR4 and RAP1 co-localize with telomeric DNA in a limited number of foci in interphase nuclei. Immunostaining of Sir2p shows that in addition to a punctate staining that coincides with Rap1 foci, Sir2p localizes to a subdomain of the nucleolus. The presence of Sir2p at both the spacer of the rDNA repeat and at telomeres is confirmed by formaldehyde cross-linking and immunoprecipitation with anti-Sir2p antibodies. In strains lacking Sir4p, Sir3p becomes concentrated in the nucleolus, by a pathway requiring SIR2 and UTH4, a gene that regulates life span in yeast. The unexpected nucleolar localization of Sir2p and Sir3p correlates with observed effects of sir mutations on rDNA stability and yeast longevity, defining a new site of action for silent information regulatory factors.
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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Antibodies, Fungal
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Antibody Specificity
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Cell Compartmentation
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Cell Nucleolus / genetics
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Cell Nucleolus / ultrastructure*
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DNA, Ribosomal*
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / immunology
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DNA-Binding Proteins / isolation & purification*
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Fluorescent Antibody Technique
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Fungal Proteins / genetics
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Fungal Proteins / immunology
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Fungal Proteins / isolation & purification
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GTP-Binding Proteins / immunology
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GTP-Binding Proteins / isolation & purification
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Histone Deacetylases*
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Models, Biological
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Polymerase Chain Reaction
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Precipitin Tests
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / ultrastructure*
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Silent Information Regulator Proteins, Saccharomyces cerevisiae*
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Sirtuin 2
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Sirtuins
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Telomere*
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Trans-Activators / genetics
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Trans-Activators / immunology
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Trans-Activators / isolation & purification*
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rap GTP-Binding Proteins
Substances
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Antibodies, Fungal
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DNA, Ribosomal
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DNA-Binding Proteins
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Fungal Proteins
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SIR3 protein, S cerevisiae
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SIR4 protein, S cerevisiae
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Silent Information Regulator Proteins, Saccharomyces cerevisiae
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Trans-Activators
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SIR2 protein, S cerevisiae
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Sirtuin 2
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Sirtuins
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Histone Deacetylases
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GTP-Binding Proteins
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rap GTP-Binding Proteins