Abstract
It is well established that acetylation of histone and nonhistone proteins is intimately linked to transcriptional activation. However, loss of acetyltransferase activity has also been shown to cause silencing defects, implicating acetylation in gene silencing. The something about silencing (Sas) 2 protein of Saccharomyces cerevisiae, a member of the MYST (MOZ, Ybf2/Sas3, Sas2, and TIP60) acetyltransferase family, promotes silencing at HML and telomeres. Here we identify a ~450-kD SAS complex containing Sas2p, Sas4p, and the tf2f-related Sas5 protein. Mutations in the conserved acetyl-CoA binding motif of Sas2p are shown to disrupt the ability of Sas2p to mediate the silencing at HML and telomeres, providing evidence for an important role for the acetyltransferase activity of the SAS complex in silencing. Furthermore, the SAS complex is found to interact with chromatin assembly factor Asf1p, and asf1 mutants show silencing defects similar to mutants in the SAS complex. Thus, ASF1-dependent chromatin assembly may mediate the role of the SAS complex in silencing.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acetyltransferases / chemistry*
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Acetyltransferases / genetics
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Acetyltransferases / isolation & purification
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Acetyltransferases / metabolism*
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Amino Acid Sequence
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Blotting, Western
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Chromatin / chemistry
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Chromatin / metabolism*
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Crosses, Genetic
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DNA Damage / genetics
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DNA Replication
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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Gene Expression Regulation, Fungal
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Gene Silencing
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Histone Acetyltransferases
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Macromolecular Substances
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Mass Spectrometry
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Molecular Chaperones
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Molecular Sequence Data
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Molecular Weight
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Mutagenesis / genetics
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Protein Binding
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Protein Structure, Tertiary
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Saccharomyces cerevisiae / chemistry
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Saccharomyces cerevisiae / enzymology*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins / chemistry
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / isolation & purification
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Saccharomyces cerevisiae Proteins / metabolism
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Silent Information Regulator Proteins, Saccharomyces cerevisiae*
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Trans-Activators / genetics
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Trans-Activators / metabolism
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Transformation, Genetic
Substances
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ASF1 protein, S cerevisiae
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Cell Cycle Proteins
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Chromatin
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Fungal Proteins
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Macromolecular Substances
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Molecular Chaperones
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SIR1 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Silent Information Regulator Proteins, Saccharomyces cerevisiae
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Trans-Activators
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Acetyltransferases
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Histone Acetyltransferases