Mutations in the Nucleosome Core Enhance Transcriptional Silencing
Open Access
- 1 March 2005
- journal article
- Published by Informa UK Limited in Molecular and Cellular Biology
- Vol. 25 (5), 1846-1859
- https://doi.org/10.1128/mcb.25.5.1846-1859.2005
Abstract
Transcriptional silencing in Saccharomyces requires specific nucleosome modifications promoted in part by a complex of Sir proteins that binds to the modified nucleosomes. Recent evidence suggests that modifications of both the histone amino termini and the core domain of nucleosomes contribute to silencing. We previously identified histone H4 mutations affecting residues in the core of the nucleosome that yield enhanced silencing at telomeres. Here we show that enhanced silencing induced by these mutations increases the proportion of cells in which telomeres and silent mating-type loci are in the silent state. One H4 mutation affects the expression of a subset of genes whose expression is altered by deletion of HTZ1, which encodes the histone variant H2A.Z, suggesting that the mutation may antagonize H2A.Z incorporation into nucleosomes. A second mutation causes the spread of silencing into subtelomeric regions that are not normally silenced in wild-type cells. Mechanistically, this mutation does not significantly accelerate the formation of silent chromatin but, rather, reduces the rate of decay of the silenced state. We propose that these mutations use distinct mechanisms to affect the dynamic interplay between activation and repression at the boundary between active and silent chromatin.Keywords
This publication has 42 references indexed in Scilit:
- A Protein Complex Containing the Conserved Swi2/Snf2-Related ATPase Swr1p Deposits Histone Variant H2A.Z into EuchromatinPLoS Biology, 2004
- Blockers and barriers to transcription: competing activities?Current Opinion in Cell Biology, 2002
- Transcript Abundance in Yeast Varies over Six Orders of MagnitudeJournal of Biological Chemistry, 2002
- Highly Specific Antibodies Determine Histone Acetylation Site Usage in Yeast Heterochromatin and EuchromatinMolecular Cell, 2001
- The Origin Recognition Complex, SIR1 , and the S Phase Requirement for SilencingScience, 1997
- An unusual form of transcriptional silencing in yeast ribosomal DNA.Genes & Development, 1997
- New heterologous modules for classical or PCR‐based gene disruptions in Saccharomyces cerevisiaeYeast, 1994
- Transcriptional silencing in yeast is associated with reduced nucleosome acetylation.Genes & Development, 1993
- Extremely conserved histone H4 N terminus is dispensable for growth but essential for repressing the silent mating loci in yeastCell, 1988
- Role of DNA replication in the repression of silent mating type loci in yeastNature, 1984