Analyses of SUM1-1-Mediated Long-Range Repression

In Saccharomyces cerevisiae, local repression is promoter specific and localized to a small region on the DNA, while silencing is promoter nonspecific, encompasses large domains of chromatin, and is stably inherited for multiple generations. Sum1p is a local repressor protein that mediates repressio...

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Bibliographic Details
Published in:Genetics (Austin) 2006-01, Vol.172 (1), p.99-112
Main Authors: Valenzuela, Lourdes, Gangadharan, Sunil, Kamakaka, Rohinton T
Format: Article
Language:English
Subjects:
Binding Sites
DNA polymerase
Gene Expression Regulation, Fungal
Gene Silencing
Genes
Genetics
Investigations
Mutation
Mutation - genetics
Nuclear Proteins - genetics
Nuclear Proteins - metabolism
Nucleosomes - genetics
Nucleosomes - metabolism
Promoter Regions, Genetic
Proteins
Repressor Proteins - genetics
Repressor Proteins - metabolism
Saccharomyces cerevisiae
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae Proteins - genetics
Saccharomyces cerevisiae Proteins - metabolism
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Summary:In Saccharomyces cerevisiae, local repression is promoter specific and localized to a small region on the DNA, while silencing is promoter nonspecific, encompasses large domains of chromatin, and is stably inherited for multiple generations. Sum1p is a local repressor protein that mediates repression of meiosis-specific genes in mitotic cells while the Sir proteins are long-range repressors that stably silence genes at HML, HMR, and telomeres. The SUM1-1 mutation is a dominant neomorphic mutation that enables the mutant protein to be recruited to the HMR locus and repress genes, even in the absence of the Sir proteins. In this study we show that the mutation in Sum1-1p enabled it to spread, and the native HMR barrier blocked it from spreading. Thus, like the Sir proteins, Sum1-1p was a long-range repressor, but unlike the Sir proteins, Sum1-1p-mediated repression was more promoter specific, repressing certain genes better than others. Furthermore, repression mediated by Sum1-1p was not stably maintained or inherited and we therefore propose that Sum1-1p-mediated long-range repression is related but distinct from silencing.
ISSN:0016-6731
1943-2631
1943-2631
DOI:10.1534/genetics.105.050427