title: The Arabidopsis SUVR4 protein is a nucleolar histone methyltransferase with preference for monomethylated H3K9.
abstract: Proteins containing the evolutionarily conserved SET domain are involved in regulation of eukaryotic gene expression and chromatin structure through their histone lysine methyltransferase (HMTase) activity. The Drosophila SU(VAR)3-9 protein and related proteins of other organisms have been associated with gene repression and heterochromatinization. In Arabidopsis there are 10 SUVH and 5 SUVR genes encoding proteins similar to SU(VAR)3-9, and 4 SUVH proteins have been shown to control heterochromatic silencing by its HMTase activity and by directing DNA methylation. The SUVR proteins differ from the SUVH proteins in their domain structure, and we show that the closely related SUVR1, SUVR2 and SUVR4 proteins contain a novel domain at their N-terminus, and a SUVR specific region preceding the SET domain. Green fluorescent protein (GFP)-fusions of these SUVR proteins preferably localize to the nucleolus, suggesting involvement in regulation of rRNA expression, in contrast to other SET-domain proteins studied so far. A novel HMTase specificity was demonstrated for SUVR4, in that monomethylated histone H3K9 is its preferred substrate in vitro.
authors.affiliation: Department of Molecular Biosciences, University of Oslo, P.O. Box 1041 Blindern, N-0316 Oslo, Norway.
authors.forename: Tage
authors.initials: T
authors.lastname: Thorstensen
authors.forename: Andreas
authors.initials: A
authors.lastname: Fischer
authors.forename: Silje V
authors.initials: SV
authors.lastname: Sandvik
authors.forename: Sylvia S
authors.initials: SS
authors.lastname: Johnsen
authors.forename: Paul E
authors.initials: PE
authors.lastname: Grini
authors.forename: Gunter
authors.initials: G
authors.lastname: Reuter
authors.forename: Reidunn B
authors.initials: RB
authors.lastname: Aalen
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002466:Cell Nucleolus / Q000201:enzymology*; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D011496:Protein Methyltransferases; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D006657:Histones; D021382:Protein Sorting Signals; C515571:SUVR1 protein, Arabidopsis; C515572:SUVR2 protein, Arabidopsis; D000076983:Histone Methyltransferases; D011496:Protein Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; C515570:SUVR4 protein, Arabidopsis; D008239:Lysine