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Transcriptional silencing functions of the yeast protein Orc1/Sir3 subfunctionalized after gene duplication
- Publication Year :
- 2010
- Publisher :
- National Academy of Sciences, 2010.
-
Abstract
- The origin recognition complex (ORC) defines origins of replication and also interacts with heterochromatin proteins in a variety of species, but how ORC functions in heterochromatin assembly remains unclear. The largest subunit of ORC, Orc1, is particularly interesting because it contains a nucleosome-binding BAH domain and because it gave rise to Sir3, a key silencing protein in Saccharomyces cerevisiae , through gene duplication. We examined whether Orc1 possessed a Sir3-like silencing function before duplication and found that Orc1 from the yeast Kluyveromyces lactis, which diverged from S. cerevisiae before the duplication, acts in conjunction with the deacetylase Sir2 and the histone-binding protein Sir4 to generate heterochromatin at telomeres and a mating-type locus. Moreover, the ability of KlOrc1 to spread across a silenced locus depends on its nucleosome-binding BAH domain and the deacetylase Sir2. Interestingly, KlOrc1 appears to act independently of the entire ORC, as other subunits of the complex, Orc4 and Orc5, are not strongly associated with silenced domains. These findings demonstrate that Orc1 functioned in silencing before duplication and suggest that Orc1 and Sir2, both of which are broadly conserved among eukaryotes, may have an ancient history of cooperating to generate chromatin structures, with Sir2 deacetylating histones and Orc1 binding to these deacetylated nucleosomes through its BAH domain.
- Subjects :
- Genetics
Multidisciplinary
Binding Sites
Saccharomyces cerevisiae Proteins
Heterochromatin
Origin Recognition Complex
Acetylation
Biology
Biological Sciences
Chromatin
Nucleosomes
Fungal Proteins
Histones
Kluyveromyces
Histone
Gene Duplication
Gene duplication
biology.protein
Origin recognition complex
Gene Silencing
Heterochromatin assembly
ORC1
BAH domain
Silent Information Regulator Proteins, Saccharomyces cerevisiae
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....867ddd4648c821229e43aa4fc192183b