title: Acetylation of H3 K56 is required for RNA polymerase II transcript elongation through heterochromatin in yeast.
abstract: In Saccharomyces cerevisiae SIR proteins mediate transcriptional silencing, forming heterochromatin structures at repressed loci. Although recruitment of transcription initiation factors can occur even to promoters packed in heterochromatin, it is unclear whether heterochromatin inhibits RNA polymerase II (RNAPII) transcript elongation. To clarify this issue, we recruited SIR proteins to the coding region of an inducible gene and characterized the effects of the heterochromatic structure on transcription. Surprisingly, RNAPII is fully competent for transcription initiation and elongation at the locus, leading to significant loss of heterochromatin proteins from the region. A search for auxiliary factors required for transcript elongation through the heterochromatic locus revealed that two proteins involved in histone H3 lysine 56 acetylation, Rtt109 and Asf1, are needed for efficient transcript elongation by RNAPII. The efficiency of transcription through heterochromatin is also impaired in a strain carrying the K56R mutation in histone H3. Our results show that H3 K56 modification is required for efficient transcription of heterochromatic locus by RNAPII, and we propose that transcription-coupled incorporation of H3 acetylated K56 (acK56) into chromatin is needed for efficient opening of heterochromatic loci for transcription.
authors.affiliation: Institute of Molecular and Cell Biology, University of Tartu, Riia 23, Tartu 51010, Estonia.
authors.forename: Signe
authors.initials: S
authors.lastname: Värv
authors.forename: Kersti
authors.initials: K
authors.lastname: Kristjuhan
authors.forename: Kadri
authors.initials: K
authors.lastname: Peil
authors.forename: Marko
authors.initials: M
authors.lastname: Lõoke
authors.forename: Tanel
authors.initials: T
authors.lastname: Mahlakõiv
authors.forename: Keiu
authors.initials: K
authors.lastname: Paapsi
authors.forename: Arnold
authors.initials: A
authors.lastname: Kristjuhan
mesh_terms: D000107:Acetylation; D016193:G1 Phase; D005800:Genes, Fungal / Q000235:genetics; D056426:Genetic Loci / Q000235:genetics; D006570:Heterochromatin / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism; D016366:Open Reading Frames; D012319:RNA Polymerase II / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D006570:Heterochromatin; D006657:Histones; D009707:Nucleosomes; D012333:RNA, Messenger; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D012319:RNA Polymerase II; D008239:Lysine