A Novel Non-SET Domain Multi-subunit Methyltransferase Required for Sequential Nucleosomal Histone H3 Methylation by the Mixed Lineage Leukemia Protein-1 (MLL1) Core Complex
A Novel Non-SET Domain Multi-subunit Methyltransferase Required for Sequential Nucleosomal Histone H3 Methylation by the Mixed Lineage Leukemia Protein-1 (MLL1) Core Complex
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DOI：
10.1074/jbc.m110.174524
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发表时间：
2011-02-04
影响因子：
4.8
通讯作者：
Cosgrove, Michael S.
中科院分区：
文献类型：
--
作者：
Patel, Anamika;Vought, Valarie E.;Cosgrove, Michael S.
真核细胞染色质内的基因表达受催化组蛋白赖氨酸甲基化的酶调控。组蛋白赖氨酸甲基转移酶具有进化上保守的SET或Dot1样结构域。我们以前报道了一个新的多亚基组蛋白H3赖氨酸4甲基转移酶缺乏同源性组蛋白赖氨酸甲基转移酶的SET或Dot1家族的鉴定。这种酶活性需要包括WRAD（WDR 5、RbBP 5、Ash2L和DPY-30）的复合物，该复合物是MLL1（混合谱系白血病蛋白-1）核心复合物的一部分，但也独立于MLL1存在于细胞中。在这里，我们报告说，WRAD酶活性所需的最小复合物包括WDR 5，RbBP 5，和阿什2L和DPY-30，虽然不需要酶活性，增加组蛋白底物特异性的WRAD复合物。我们还表明，WRAD需要锌的催化活性，显示米氏动力学，并抑制S-腺苷同型半胱氨酸。此外，我们证明，WRAD优先甲基化组蛋白H3的赖氨酸4的上下文内的H3/H4四聚体，但不甲基化核小体组蛋白H3本身。相比之下，我们发现MLL1和WRAD是核小体组蛋白H3甲基化所必需的，我们提供的证据表明，每个在核小体底物的识别和甲基化中起着不同的结构和催化作用。我们的研究结果表明，WRAD是一种新的H3K4甲基转移酶，其功能包括调节MLL1核心复合物的底物和产物特异性。
Gene expression within the context of eukaryotic chromatin is regulated by enzymes that catalyze histone lysine methylation. Histone lysine methyltransferases that have been identified to date possess the evolutionarily conserved SET or Dot1-like domains. We previously reported the identification of a new multi-subunit histone H3 lysine 4 methyltransferase lacking homology to the SET or Dot1 family of histone lysine methyltransferases. This enzymatic activity requires a complex that includes WRAD (WDR5, RbBP5, Ash2L, and DPY-30), a complex that is part of the MLL1 (mixed lineage leukemia protein-1) core complex but that also exists independently of MLL1 in the cell. Here, we report that the minimal complex required for WRAD enzymatic activity includes WDR5, RbBP5, and Ash2L and that DPY-30, although not required for enzymatic activity, increases the histone substrate specificity of the WRAD complex. We also show that WRAD requires zinc for catalytic activity, displays Michaelis-Menten kinetics, and is inhibited by S-adenosylhomocysteine. In addition, we demonstrate that WRAD preferentially methylates lysine 4 of histone H3 within the context of the H3/H4 tetramer but does not methylate nucleosomal histone H3 on its own. In contrast, we find that MLL1 and WRAD are required for nucleosomal histone H3 methylation, and we provide evidence suggesting that each plays distinct structural and catalytic roles in the recognition and methylation of a nucleosome substrate. Our results indicate that WRAD is a new H3K4 methyltransferase with functions that include regulating the substrate and product specificities of the MLL1 core complex.