Dnmt3a and Dnmt1 functionally cooperate during de novo methylation of DNA
Dnmt3a and Dnmt1 functionally cooperate during de novo methylation of DNA
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DOI：
10.1046/j.1432-1033.2002.03198.x
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发表时间：
2002-10-01
期刊：
影响因子：
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通讯作者：
Jeltsch, A
中科院分区：
文献类型：
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作者：
Fatemi, M;Hermann, A;Jeltsch, A
Dnmt3a是一种从头DNA甲基转移酶，修饰未甲基化的DNA。相反，Dnmt 1显示高度偏好半甲基化DNA。然而，Dnmt 1可以被激活用于未修饰DNA的甲基化。我们在这里表明，Dnmt3a和Dnmt1 DNA甲基转移酶在功能上合作的DNA从头甲基化，因为一个五倍的刺激甲基化活性观察到，如果这两种酶都存在。如果在Dnmt 1之前使用Dnmt 3a，则观察到刺激，但如果在Dnmt 3a之前与Dnmt 1孵育，则观察不到刺激，这表明Dnmt 3a对DNA的甲基化刺激Dnmt 1，并且不需要Dnmt 1和Dnmt 3a的物理相互作用。如果将Dnmt 1和Dnmt 3a一起孵育，则观察到轻微增加的刺激，这可能是由于这些酶的直接相互作用。此外，我们表明，Dnmt 1是刺激未修饰的DNA的甲基化，如果DNA已经携带一些甲基。我们的结论是，在Dnmt 3a启动DNA的从头甲基化后，Dnmt 1被预先存在的甲基基团激活并进一步甲基化DNA。我们的数据表明，Dnmt 1也在DNA的从头甲基化中发挥作用。该模型与这些酶的生物化学性质一致，并为不同DNA MTases在体内也观察到的DNA从头甲基化中的功能合作提供了机制基础。
Dnmt3a is a de novo DNA methyltransferase that modifies unmethylated DNA. In contrast Dnmt1 shows high preference for hemimethylated DNA. However, Dnmt1 can be activated for the methylation of unmodified DNA. We show here that the Dnmt3a and Dnmt1 DNA methyltransferases functionally cooperate in de novo methylation of DNA, because a fivefold stimulation of methylation activity is observed if both enzymes are present. Stimulation is observed if Dnmt3a is used before Dnmt1, but not if incubation with Dnmt1 precedes Dnmt3a, demonstrating that methylation of the DNA by Dnmt3a stimulates Dnmt1 and that no physical interaction of Dnmt1 and Dnmt3a is required. If Dnmt1 and Dnmt3a were incubated together a slightly increased stimulation is observed that could be due to a direct interaction of these enzymes. In addition, we show that Dnmt1 is stimulated for methylation of unmodified DNA if the DNA already carries some methyl groups. We conclude that after initiation of de novo methylation of DNA by Dnmt3a, Dnmt1 becomes activated by the pre-existing methyl groups and further methylates the DNA. Our data suggest that Dnmt1 also has a role in de novo methylation of DNA. This model agrees with the biochemical properties of these enzymes and provides a mechanistic basis for the functional cooperation of different DNA MTases in de novo methylation of DNA that has also been observed in vivo .