Chromatin targeting of de novo DNA methyltransferases by the PWWP domain
Chromatin targeting of de novo DNA methyltransferases by the PWWP domain
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PWWP 结构域对从头 DNA 甲基转移酶的染色质靶向
DOI：
10.1074/jbc.m312296200
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发表时间：
2004-06-11
影响因子：
4.8
通讯作者：
Xu, GL
中科院分区：
文献类型：
--
作者：
Ge, YZ;Pu, MT;Xu, GL
哺乳动物基因组的DNA甲基化模式在配子发生和早期胚胎发育中产生。两种从头DNA甲基转移酶Dnmt 3a和Dnmt 3b负责该过程。这两种酶都含有一个长的N-末端调控区连接到一个保守的C-末端结构域负责催化活性。虽然N-末端区域的PWWP结构域已被证明在体外结合DNA，但尚不清楚DNA甲基转移酶如何在体内进入染色质中的底物。我们在这里表明，这两种蛋白质与染色质，包括哺乳动物细胞中的有丝分裂染色体，和PWWP结构域是必不可少的染色质靶向的酶。PWWP介导的染色质靶向的功能意义由以下事实提出：人DNMT 3B的该结构域中的错义突变引起免疫缺陷、着丝粒异染色质不稳定性、面部异常（ICF）综合征，其特征在于卫星DNA中的甲基化丧失、着丝粒周围不稳定性和免疫缺陷。我们证明了突变蛋白完全失去了其染色质靶向能力。我们的数据建立PWWP域作为一种新的染色质/染色体靶向模块，并建议PWWP介导的染色质协会是必不可少的从头甲基转移酶在发展过程中的功能。
DNA methylation patterns of mammalian genomes are generated in gametogenesis and early embryonic development. Two de novo DNA methyltransferases, Dnmt3a and Dnmt3b, are responsible for the process. Both enzymes contain a long N-terminal regulatory region linked to a conserved C-terminal domain responsible for the catalytic activity. Although a PWWP domain in the N-terminal region has been shown to bind DNA in vitro, it is unclear how the DNA methyltransferases access their substrate in chromatin in vivo. We show here that the two proteins are associated with chromatin including mitotic chromosomes in mammalian cells, and the PWWP domain is essential for the chromatin targeting of the enzymes. The functional significance of PWWP-mediated chromatin targeting is suggested by the fact that a missense mutation in this domain of human DNMT3B causes immunodeficiency, centromeric heterochromatin instability, facial anomalies (ICF) syndrome, which is characterized by loss of methylation in satellite DNA, pericentromeric instability, and immunodeficiency. We demonstrate that the mutant protein completely loses its chromatin targeting capacity. Our data establish the PWWP domain as a novel chromatin/chromosome-targeting module and suggest that the PWWP-mediated chromatin association is essential for the function of the de novo methyltransferases during development.