Dimerization of Sir3 via its C-terminal winged helix domain is essential for yeast heterochromatin formation
| Autor: | Mariano Oppikofer, Susan M. Gasser, Markus Hassler, Andreas G. Ladurner, Jeremy J. Keusch, Heinz Gut, Stephanie Kueng |
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| Rok vydání: | 2013 |
| Předmět: |
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Molecular Chromatin Immunoprecipitation Protein Conformation Heterochromatin Molecular Sequence Data Saccharomyces cerevisiae Winged Helix Biology Polymerase Chain Reaction Article General Biochemistry Genetics and Molecular Biology Evolution Molecular Histone H4 03 medical and health sciences Transcription (biology) Immunoprecipitation Nucleosome Amino Acid Sequence Gene Silencing ORC1 Molecular Biology Silent Information Regulator Proteins Saccharomyces cerevisiae DNA Primers 030304 developmental biology Genetics 0303 health sciences General Immunology and Microbiology General Neuroscience Genetic Complementation Test 030302 biochemistry & molecular biology SIR proteins Chromatin Nucleosomes Cell biology Mutagenesis Crystallization Dimerization Sequence Alignment |
| Zdroj: | The EMBO journal |
| DOI: | 10.1038/emboj.2012.343 |
| Popis: | Gene silencing in budding yeast relies on the binding of the Silent Information Regulator (Sir) complex to chromatin, which is mediated by extensive interactions between the Sir proteins and nucleosomes. Sir3, a divergent member of the AAA+ ATPase-like family, contacts both the histone H4 tail and the nucleosome core. Here, we present the structure and function of the conserved C-terminal domain of Sir3, comprising 138 amino acids. This module adopts a variant winged helix-turn-helix (wH) architecture that exists as a stable homodimer in solution. Mutagenesis shows that the self-association mediated by this domain is essential for holo-Sir3 dimerization. Its loss impairs Sir3 loading onto nucleosomes in vitro and eliminates silencing at telomeres and HM loci in vivo. Replacing the Sir3 wH domain with an unrelated bacterial dimerization motif restores both HM and telomeric repression in sir3Δ cells. In contrast, related wH domains of archaeal and human members of the Orc1/Sir3 family are monomeric and have DNA binding activity. We speculate that a dimerization function for the wH evolved with Sir3's ability to facilitate heterochromatin formation. |
| Databáze: | OpenAIRE |
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