title: The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae.
abstract: Transcriptional silencing in Saccharomyces cerevisiae occurs at several genomic sites including the silent mating-type loci, telomeres, and the ribosomal DNA (rDNA) tandem array. Epigenetic silencing at each of these domains is characterized by the absence of nearly all histone modifications, including most prominently the lack of histone H4 lysine 16 acetylation. In all cases, silencing requires Sir2, a highly-conserved NAD(+)-dependent histone deacetylase. At locations other than the rDNA, silencing also requires additional Sir proteins, Sir1, Sir3, and Sir4 that together form a repressive heterochromatin-like structure termed silent chromatin. The mechanisms of silent chromatin establishment, maintenance, and inheritance have been investigated extensively over the last 25 years, and these studies have revealed numerous paradigms for transcriptional repression, chromatin organization, and epigenetic gene regulation. Studies of Sir2-dependent silencing at the rDNA have also contributed to understanding the mechanisms for maintaining the stability of repetitive DNA and regulating replicative cell aging. The goal of this comprehensive review is to distill a wide array of biochemical, molecular genetic, cell biological, and genomics studies down to the "nuts and bolts" of silent chromatin and the processes that yield transcriptional silencing.
authors: Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854.
authors: Marc R
authors: MR
authors: Gartenberg
authors: Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia 22908 jss5y@virginia.edu.
authors: Jeffrey S
authors: JS
authors: Smith
mesh_terms: D002843:Chromatin / Q000235:genetics*; D044127:Epigenesis, Genetic / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D006570:Heterochromatin / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000235:genetics*; D056565:Sirtuin 2 / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D006570:Heterochromatin; C084121:SIR1 protein, S cerevisiae; C084122:SIR3 protein, S cerevisiae; C061573:SIR4 protein, S cerevisiae; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; C087778:SIR2 protein, S cerevisiae; D056565:Sirtuin 2
keywords: Sir2; chromatin; histone deacetylation; silencing; yeast