title: NoRC-dependent nucleosome positioning silences rRNA genes.
abstract: Previous studies have established that the Snf2h-containing chromatin remodeling complex NoRC mediates epigenetic silencing of a subset of rRNA genes (rDNA) by recruiting enzymatic activities that modify histones and methylate DNA. Here we have analyzed nucleosome positions at the murine rDNA promoter and show that active and silent rDNA copies are characterized not only by specific epigenetic marks but also by differently positioned nucleosomes. At active genes the promoter-bound nucleosome covers nucleotides from -157 to -2, whereas at silent genes the nucleosome is positioned 25 nucleotides further downstream. We provide evidence that NoRC is the molecular machine that shifts the promoter-bound nucleosome downstream of the transcription start site into a translational position that is unfavorable for transcription complex formation.
authors.affiliation: Division of Molecular Biology of the Cell II, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
authors.forename: Junwei
authors.initials: J
authors.lastname: Li
authors.forename: Gernot
authors.initials: G
authors.lastname: Längst
authors.forename: Ingrid
authors.initials: I
authors.lastname: Grummt
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology; D000818:Animals; D002454:Cell Differentiation; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D045584:Chromosome Positioning; D020868:Gene Silencing; D020459:Genes, rRNA; D051379:Mice; D041681:NIH 3T3 Cells; D009707:Nucleosomes / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D014158:Transcription, Genetic; D000092468:Bromodomain Containing Proteins
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D009707:Nucleosomes; C499051:Baz2a protein, mouse; D000092468:Bromodomain Containing Proteins