title: Preferential dimethylation of histone H4 lysine 20 by Suv4-20.
abstract: Post-translational modifications of histone tails direct nuclear processes including transcription, DNA repair, and chromatin packaging. Lysine 20 of histone H4 is mono-, di-, or trimethylated in vivo, but the regulation and significance of these methylations is poorly understood. The SET domain proteins PR-Set7 and Suv4-20 have been implicated in mono- and trimethylation, respectively; however, enzymes that dimethylate lysine 20 have not been identified. Here we report that Drosophila Suv4-20 is a mixed product specificity methyltransferase that dimethylates approximately 90% and trimethylates less than 5% of total H4 at lysine 20 in S2 cells. Trimethylation, but not dimethylation, is reduced in Drosophila larvae lacking HP1, suggesting that an interaction with HP1 regulates the product specificity of Suv4-20 and enrichment of trimethyllysine 20 within heterochromatin. Similar to the Drosophila enzyme, human Suv4-20h1/h2 enzymes generate di- and trimethyllysine 20. PR-Set7 and Suv4-20 are both required for normal levels of methylation, suggesting they have non-redundant functions. Alterations in the level of lysine 20 methylation following knock-down or overexpression of Suv4-20 did not affect lysine 16 acetylation, revealing that these two modifications are not competitive in vivo. Depletion of Suv4-20h1/h2 in HeLa cells impaired the formation of 53BP1 foci, suggesting dimethyllysine 20 is required for a proper DNA damage response. Collectively, the data indicate that Suv4-20 generates nearly ubiquitous dimethylation that facilitates the DNA damage response and selective trimethylation that is involved in heterochromatin formation.
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Yang
authors.forename: James J
authors.initials: JJ
authors.lastname: Pesavento
authors.forename: Taylor W
authors.initials: TW
authors.lastname: Starnes
authors.forename: Diane E
authors.initials: DE
authors.lastname: Cryderman
authors.forename: Lori L
authors.initials: LL
authors.lastname: Wallrath
authors.forename: Neil L
authors.initials: NL
authors.lastname: Kelleher
authors.forename: Craig A
authors.initials: CA
authors.lastname: Mizzen
mesh_terms: D000818:Animals; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D004249:DNA Damage; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology*; D006367:HeLa Cells; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008239:Lysine / Q000378:metabolism*; D013058:Mass Spectrometry; D008745:Methylation; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1; D000090266:Chromobox Protein Homolog 5; C487546:Hmt4-20 protein, Drosophila; D004248:DNA (Cytosine-5-)-Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D008239:Lysine