Abstract
The Sir3 protein helps form telomeric heterochromatin by interacting with hypoacetylated histone H4 lysine 16 (H4-Lys16). The molecular nature of the heterochromatin boundary is still unknown. Here we show that the MYST-like acetyltransferase Sas2p is required for the acetylation (Ac) of H4-Lys16 in euchromatin. In a sas2Delta strain or a phenocopy Lys16Arg mutant, Sir3p spreads from roughly 3 kb to roughly 15 kb, causing hypoacetylation and repression of adjacent chromatin. We also found that disruption of Sir3p binding in a deacetylase-deficient Sir 2Delta strain can be suppressed by sas2Delta. These data indicate that opposing effects of Sir2p and Sas2p on acetylation of H4-Lys16 maintain the boundary at telomeric heterochromatin.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acetylation
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Acetyltransferases / metabolism
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Acetyltransferases / physiology*
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Arginine
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Chromatin / metabolism
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Heterochromatin / chemistry
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Heterochromatin / metabolism*
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Histone Acetyltransferases
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Histone Deacetylases / metabolism
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Histone Deacetylases / physiology*
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Histones / metabolism*
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Lysine / metabolism*
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Mutation
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Precipitin Tests
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Promoter Regions, Genetic
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Protein Binding
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Protein Structure, Tertiary
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RNA, Messenger / metabolism
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Reverse Transcriptase Polymerase Chain Reaction
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Saccharomyces cerevisiae Proteins / metabolism
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Saccharomyces cerevisiae Proteins / physiology*
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Silent Information Regulator Proteins, Saccharomyces cerevisiae / metabolism
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Silent Information Regulator Proteins, Saccharomyces cerevisiae / physiology*
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Sirtuin 2
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Sirtuins / metabolism
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Sirtuins / physiology*
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Telomere / ultrastructure
Substances
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Chromatin
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Heterochromatin
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Histones
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RNA, Messenger
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Saccharomyces cerevisiae Proteins
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Silent Information Regulator Proteins, Saccharomyces cerevisiae
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Arginine
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Acetyltransferases
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Histone Acetyltransferases
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Sas2 protein, S cerevisiae
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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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Lysine