Automethylation of G9a and its implication in wider substrate specificity and HP1 binding.
Automethylation of G9a and its implication in wider substrate specificity and HP1 binding.
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G9a的自甲基化及其对更广泛的底物特异性和HP1结合的影响。
DOI：
10.1093/nar/gkm726
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发表时间：
2007
影响因子：
14.9
通讯作者：
Pradhan, Sriharsa
中科院分区：
文献类型：
--
作者：
Chin, Hang Gyeong;Esteve, Pierre-Olivier;Pradhan, Mihika;Benner, Jack;Patnaik, Debasis;Carey, Michael F;Pradhan, Sriharsa
组蛋白上赖氨酸残基的甲基化参与转录基因调控。组蛋白 H3 的赖氨酸 9 甲基化是一种转录抑制信号，由包含 AdoMet 依赖性酶的 SET 结构域家族介导。 G9a 甲基转移酶是一种常染色质组蛋白 H3 赖氨酸 9 甲基转移酶。此处，G9a 显示除组蛋白 H3 之外的其他细胞蛋白甲基化，包括 K239 残基的自动甲基化。 G9a 的自动甲基化不会损害或激活体外酶活性。 G9a 侧翼靶标 K239 (ARKT) 的自动甲基化基序与组蛋白 H3 赖氨酸 9 区 (ARKS) 相似，并且与 EuHMT (ARKT) 和 mAM (ARKT) 中的氨基酸残基相同。在稳态动力学测定条件下，全长 G9a 可以有效地甲基化代表 H3、G9a、mAM 和 EuHMT 的 ARKS/T 基序的肽。 ARKT 基序上 G9a 的自动甲基化为 HP1 类蛋白质创建了一个结合位点，基序中赖氨酸的突变会损害这种结合。在 COS-7 细胞中，野生型 G9a 的 GFP 融合与 HP1α 和 HP1γ 同种型共定位，而 G9a 突变体与 K239A 的共定位较差。因此，除了赖氨酸甲基化的转录抑制和调节作用之外，非组蛋白甲基化可能为细胞蛋白质-蛋白质相互作用创造结合位点。
Methylation of lysine residues on histones participates in transcriptional gene regulation. Lysine 9 methylation of histone H3 is a transcriptional repression signal, mediated by a family of SET domain containing AdoMet-dependent enzymes. G9a methyltransferase is a euchromatic histone H3 lysine 9 methyltransferase. Here, G9a is shown to methylate other cellular proteins, apart from histone H3, including automethylation of K239 residue. Automethylation of G9a did not impair or activate the enzymatic activity in vitro. The automethylation motif of G9a flanking target K239 (ARKT) has similarity with histone H3 lysine 9 regions (ARKS), and is identical to amino acids residues in EuHMT (ARKT) and mAM (ARKT). Under steady-state kinetic assay conditions, full-length G9a methylates peptides representing ARKS/T motif of H3, G9a, mAM and EuHMT efficiently. Automethylation of G9a at ARKT motif creates a binding site for HP1 class of protein and mutation of lysine in the motif impairs this binding. In COS-7 cells GFP fusion of the wild-type G9a co-localized with HP1α and HP1γ isoforms whereas the G9a mutant with K239A displayed poor co-localization. Thus, apart from transcriptional repression and regulatory roles of lysine methylation, the non-histone protein methylation may create binding sites for cellular protein–protein interactions.