Methylation of a Histone Mimic within the Histone Methyltransferase G9a Regulates Protein Complex Assembly

Sampath, Srihari C.; Marazzi, Ivan; Yap, Kyoko L.; Sampath, Srinath C.; Krutchinsky, Andrew N.; Mecklenbräuker, Ingrid; Viale, Agnès; Rudensky, Eugene; Zhou, Ming‐Ming; Chait, Brian T.; Tarakhovsky, Alexander

doi:10.1016/j.molcel.2007.06.026

Cited by 218 publications

(236 citation statements)

References 47 publications

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“…1A and Dataset S1). Validating our approach, G9a and GLP themselves were identified, as well as a number of previously known G9a-interacting partners, including Wiz (20), DNMT1 (21), and HP1γ (22,23). In addition, several previously unknown G9a-GLP interacting proteins, including both coactivators and corepressors, were identified, which is consistent with the dual role of G9a in regulating transcription (Fig.…”

Section: Resultssupporting

confidence: 75%

Maintenance of gene silencing by the coordinate action of the H3K9 methyltransferase G9a/KMT1C and the H3K4 demethylase Jarid1a/KDM5A

Chaturvedi

Somasundaram

Singh

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Chromatin remodeling is essential for controlling the expression of genes during development. The histone-modifying enzyme G9a/KMT1C can act both as a coactivator and a corepressor of transcription. Here, we show that the dual function of G9a as a coactivator vs. a corepressor entails its association within two distinct protein complexes, one containing the coactivator Mediator and one containing the corepressor Jarid1a/KDM5A. Functionally, G9a is important in stabilizing the Mediator complex for gene activation, whereas its repressive function entails a coordinate action with the histone H3 lysine 4 (H3K4) demethylase Jarid1a for the maintenance of gene repression. The essential nature of cross-talk between the histone methyltransferase G9a and the demethylase Jarid1a is demonstrated on the embryonic E y -globin gene, where the concurrent introduction of repressive histone marks (dimethylated H3K9 and dimethylated H3K27) and removal of activating histone mark (trimethylated H3K4) is required for maintenance of gene silencing. Taken together with our previous demonstration of cross-talk between UTX and MLL2 to mediate activation of the adult β maj -globin gene, these data suggest a model where “active” and “repressive” cross-talk between histone-modifying enzymes coexist on the same multigene locus and play a crucial role in the precise control of developmentally regulated gene expression.

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Section: Resultssupporting

confidence: 75%

Maintenance of gene silencing by the coordinate action of the H3K9 methyltransferase G9a/KMT1C and the H3K4 demethylase Jarid1a/KDM5A

Chaturvedi

Somasundaram

Singh

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…To date, we have not detected these modifications by MS analysis, but we cannot exclude the possibility that these PTMs exist in low abundance (Ͻ0.1% of total mH2A) or take place only during certain cell cycle phases. Interestingly, a ''methyl/phos histone mimic'' corresponding to the above motif has recently been identified in the histone methyltransferase G9a, suggesting a broader role for this motif (43).…”

Section: Discussionmentioning

confidence: 99%

A phosphorylated subpopulation of the histone variant macroH2A1 is excluded from the inactive X chromosome and enriched during mitosis

Bernstein

Muratore-Schroeder²,

Diaz

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Histone variants play an important role in numerous biological processes through changes in nucleosome structure and stability and possibly through mechanisms influenced by posttranslational modifications unique to a histone variant. The family of histone H2A variants includes members such as H2A.Z, the DNA damageassociated H2A.X, macroH2A (mH2A), and H2ABbd (Barr bodydeficient). Here, we have undertaken the challenge to decipher the posttranslational modification-mediated ''histone code'' of mH2A, a variant generally associated with certain forms of condensed chromatin such as the inactive X chromosome in female mammals. By using female human cells as a source of mH2A, endogenous mH2A was purified and analyzed by mass spectrometry. Although mH2A is in low abundance compared with conventional histones, we identified a phosphorylation site, S137ph, which resides within the ''hinge'' region of mH2A. This lysine-rich hinge is an Ϸ30-aa stretch between the H2A and macro domains, proposed to bind nucleic acids. A specific antibody to S137ph was raised; by using this reagent, S137 phosphorylation was found to be present in both male and female cells and on both splice variants of the mH2A1 gene. Although mH2A is generally enriched on the inactive X chromosome in female cells, mH2AS137ph is excluded from this heterochromatic structure. Thus, a phosphorylated subpopulation of mH2A appears to play a unique role in chromatin regulation beyond X inactivation. We provide evidence that S137ph is enriched in mitosis, suggestive of a role in the regulation of mH2A posttranslational modifications throughout the cell cycle.macroH2A ͉ histone modifications ͉ phosphorylation

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“…We detected strong methylation-specific binding of HP1β to the automethylation site of G9a (as seen in ref. 16 ), and to the peptides derived from H3, CDYL1 and WIZ (Fig. 3b).…”

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confidence: 99%

Protein lysine methyltransferase G9a acts on non-histone targets

et al. 2008

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By methylation of peptide arrays, we determined the specificity profile of the protein methyltransferase G9a. We show that it mostly recognizes an Arg-Lys sequence and that its activity is inhibited by methylation of the arginine residue. Using the specificity profile, we identified new non-histone protein targets of G9a, including CDYL1, WIZ, ACINUS and G9a (automethylation), as well as peptides derived from CSB. We demonstrate potential downstream signaling pathways for methylation of non-histone proteins.Epigenetic regulation of gene expression by covalent modification of histone proteins and methylation of DNA controls development and disease processes 1 . Post-translational modification of histone proteins includes acetylation, phosphorylation and methylation. Many of these modifications occur on the N-terminal tails of the histone proteins that protrude from the nucleosome. Methylation of lysine residues in histone tails has been identified in histone H3 lysine residues 4, 9, 27 and 36; in histone H4 lysine 20; and in histone H1b lysine 25. Each of these methylations has different biological functions 1 .The first histone lysine methyltransferase was identified in 2000 (ref.2), and today about 30 different enzymes are known in different species 1 . Most protein lysine methyltransferases (PKMTs) contain a SET domain, which harbors the active center of the enzymes 3 . Here, we investigate the substrate sequence specificity of the human G9a PKMT, which is important for the euchromatic histone H3K9 methylation that is essential for early embryogenesis 4 , the propagation of imprints 5 and control of DNA methylation 6 . Knockout of G9a results in a decrease of global H3K9me1 and H3K9me2 levels 7 . In vitro G9a generates mainly H3K9me1 and H3K9me2 (ref. 8), as well as H3K9me3 after long incubation 9 . In contrast to the Dim-5 and Suv39H1 H3K9 methyltransferases, G9a methylates not only H3K9 but also H3K27 (ref. 10), which implicates different specificities in peptide recognition. To analyze the substrate specificity of PKMTs, we prepared peptide arrays on functionalized cellulose membranes using the first 21 residues of histone H3 as template 11 (Supplementary Methods online). The membranes were incubated with G9a in the presence of radioactively labeled [methyl-3 H]-S-adenosyl-L-methionine ( 3 H-AdoMet, 1), and the transfer of methyl groups to the immobilized peptides was detected by autoradiography ( Supplementary Fig. 1 online). To quantify the contribution of each amino acid to the recognition of the substrate and display it graphically, the discrimination factor of G9a at each position was calculated (Fig. 1a). The results showed that G9a interacts with H3 residues 6-11, which agrees with a report describing a heptapeptide of the histone H3 tail (TARKSTG) as the minimal substrate methylated by G9a (ref. 12). In addition to Lys9 (the target of methylation), Arg8 is the most important specificity determinant for G9a. Any other amino acid substituted at that position completely abolished the activity...

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Methylation of a Histone Mimic within the Histone Methyltransferase G9a Regulates Protein Complex Assembly

Cited by 218 publications

References 47 publications

Maintenance of gene silencing by the coordinate action of the H3K9 methyltransferase G9a/KMT1C and the H3K4 demethylase Jarid1a/KDM5A

Maintenance of gene silencing by the coordinate action of the H3K9 methyltransferase G9a/KMT1C and the H3K4 demethylase Jarid1a/KDM5A

A phosphorylated subpopulation of the histone variant macroH2A1 is excluded from the inactive X chromosome and enriched during mitosis

Protein lysine methyltransferase G9a acts on non-histone targets

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