title: Arabidopsis histone deacetylase HDA6 is required for maintenance of transcriptional gene silencing and determines nuclear organization of rDNA repeats.
abstract: Histone acetylation and deacetylation are connected with transcriptional activation and silencing in many eukaryotic organisms. Gene families for enzymes that accomplish these modifications show a surprising multiplicity in sequence and expression levels, suggesting a high specificity for different targets. We show that mutations in Arabidopsis (Arabidopsis thaliana) HDA6, a putative class I histone deacetylase gene, result in loss of transcriptional silencing from several repetitive transgenic and endogenous templates. Surprisingly, total levels of histone H4 acetylation are only slightly affected, whereas significant hyperacetylation is restricted to the nucleolus organizer regions that contain the rDNA repeats. This switch coincides with an increase of histone 3 methylation at Lys residue 4, a modified DNA methylation pattern, and a concomitant decondensation of the chromatin. These results indicate that HDA6 might play a role in regulating activity of rRNA genes, and this control might be functionally linked to silencing of other repetitive templates and to its previously assigned role in RNA-directed DNA methylation.
authors.affiliation: Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland. aline.probst@bioveg.unige.ch
authors.forename: Aline V
authors.initials: AV
authors.lastname: Probst
authors.forename: Mathilde
authors.initials: M
authors.lastname: Fagard
authors.forename: Florence
authors.initials: F
authors.lastname: Proux
authors.forename: Philippe
authors.initials: P
authors.lastname: Mourrain
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Boutet
authors.forename: Keith
authors.initials: K
authors.lastname: Earley
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lawrence
authors.forename: Craig S
authors.initials: CS
authors.lastname: Pikaard
authors.forename: Jane
authors.initials: J
authors.lastname: Murfett
authors.forename: Ian
authors.initials: I
authors.lastname: Furner
authors.forename: Hervé
authors.initials: H
authors.lastname: Vaucheret
authors.forename: Ortrun
authors.initials: O
authors.lastname: Mittelsten Scheid
mesh_terms: D000107:Acetylation; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins; D001483:Base Sequence; D019175:DNA Methylation; D018744:DNA, Plant / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D020868:Gene Silencing; D006655:Histone Deacetylases / Q000235:genetics*; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D004275:DNA, Ribosomal; D006657:Histones; C432452:AT5G63110 protein, Arabidopsis; D006655:Histone Deacetylases