title: RNA polymerase I propagates unidirectional spreading of rDNA silent chromatin.
abstract: The ribosomal DNA (rDNA) tandem array in Saccharomyces cerevisiae induces transcriptional silencing of RNA polymerase II-transcribed genes. This SIR2-dependent form of repression (rDNA silencing) also functions to limit rDNA recombination and is involved in life span control. In this report, we demonstrate that rDNA silencing spreads into the centromere-proximal unique sequence located downstream of RNA polymerase I (Pol I) transcription, but fails to enter the upstream telomere-proximal sequences. The spreading of silencing correlates with SIR2-dependent histone H3 and H4 deacetylation and can be extended by SIR2 overexpression. Surprisingly, rDNA silencing required transcription by RNA polymerase I and the direction of spreading was controlled by the direction of Pol I transcription.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Buck
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Sandmeier
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Smith
mesh_terms: D024509:3' Flanking Region / Q000235:genetics; D024506:5' Flanking Region / Q000235:genetics; D001483:Base Sequence / Q000235:genetics; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism; D004256:DNA Polymerase I / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D020868:Gene Silencing / Q000502:physiology*; D017930:Genes, Reporter / Q000235:genetics; D006655:Histone Deacetylases / Q000235:genetics; D006657:Histones / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012318:RNA Polymerase I / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000235:genetics; D056565:Sirtuin 2; D037761:Sirtuins / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics*
chemical_list: D002843:Chromatin; D004275:DNA, Ribosomal; D006657:Histones; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D012318:RNA Polymerase I; D004256:DNA Polymerase I; C087778:SIR2 protein, S cerevisiae; D056565:Sirtuin 2; D037761:Sirtuins; D006655:Histone Deacetylases