Biochemical characterization of maintenance DNA methyltransferase DNMT-1 from silkworm, Bombyx mori
Biochemical characterization of maintenance DNA methyltransferase DNMT-1 from silkworm, Bombyx mori
复制标题
DOI：
10.1016/j.ibmb.2015.01.008
复制
发表时间：
2015-03-01
影响因子：
3.8
通讯作者：
Kusakabe, Takahiro
中科院分区：
文献类型：
--
作者：
Mitsudome, Takumi;Mon, Hiroaki;Kusakabe, Takahiro
DNA甲基化是参与脊椎动物和无脊椎动物基因表达的重要表观遗传机制。一般来说，DNA 甲基化谱是由从头 DNA 甲基转移酶 (DNMT-3A、-3B) 和维持 DNA 甲基转移酶 (DNMT-1) 建立的。与非甲基化 DNA 相比，DNMT-1 对半甲基化 DNA 具有强烈的底物偏好。由于家蚕基因组缺乏明显的从头DNMT同源物，目前尚不清楚家蚕染色体如何建立和维持其DNA甲基化谱。作为解开这个谜团的第一步，我们使用杆状病毒表达系统纯化了重组 BmDNMT-1，并表征了其 DNA 结合和 DNA 甲基化活性。我们发现 BmDNMT-1 优先甲基化半甲基化 DNA，尽管与非甲基化和半甲基化 DNA 均结合。有趣的是，在存在或不存在甲基供体 S-腺苷甲硫氨酸 (AdoMet) 的情况下，BmDNMT-1 与 DNA 形成复合物，并且 Zn2+ 和 Mn2+ 促进了 AdoMet 依赖性复合物的形成。我们的结果提供了明确的证据，表明 BmDNMT-1 保留了维持 DNMT 的功能，但其对金属离子的敏感性与哺乳动物 DNMT-1 不同。 (C) 2015 Elsevier Ltd. 保留所有权利。
DNA methylation is an important epigenetic mechanism involved in gene expression of vertebrates and invertebrates. In general, DNA methylation profile is established by de novo DNA methyltransferases (DNMT-3A, -3B) and maintainance DNA methyltransferase (DNMT-1). DNMT-1 has a strong substrate preference for hemimethylated DNA over the unmethylated one. Because the silkworm genome lacks an apparent homologue of de novo DNMT, it is still unclear that how silkworm chromosome establishes and maintains its DNA methylation profile. As the first step to unravel this enigma, we purified recombinant BmDNMT-1 using baculovirus expression system and characterized its DNA-binding and DNA methylation activity. We found that the BmDNMT-1 preferentially methylates hemimethylated DNA despite binding to both unmethylated and hemimethylated DNA. Interestingly, BmDNMT-1 formed a complex with DNA in the presence or absence of methyl group donor, S-Adenosylmethionine (AdoMet) and the AdoMet-dependent complex formation was facilitated by Zn2+ and Mn2+. Our results provide clear evidence that BmDNMT-1 retained the function as maintenance DNMT but its sensitivity to metal ions is different from mammalian DNMT-1. (C) 2015 Elsevier Ltd. All rights reserved.