Marhold J, Rothe N, Pauli A, Mund C, Kuehle K, Brueckner B, Lyko F
Research Group Epigenetics, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany.
Insect Mol Biol. 2004 Apr;13(2):117-23. doi: 10.1111/j.0962-1075.2004.00466.x.
DNA methylation is a central mechanism of epigenetic regulation. Whereas vertebrate DNA methylation requires at least four different DNA methyltransferases, Drosophila melanogaster only utilizes a single, Dnmt2-like enzyme. This profound difference has raised the question of the evolutionary significance of the Drosophila methylation system. We have now identified Dnmt2-like open reading frames in the genome sequences of Drosophila pseudoobscura and Anopheles gambiae. These genes represent the only candidate DNA methyltransferases in their respective genomes. Consistent with a catalytic activity of Dnmt2 proteins, we could also demonstrate low but significant levels of DNA methylation in genomic DNA from these species. Lastly, we were also able to detect highly conserved Dnmt2-like open reading frames and concomitant DNA methylation in several additional Drosophila species, which suggests that Dnmt2-mediated DNA methylation has been conserved over a considerable evolutionary distance.
DNA甲基化是表观遗传调控的核心机制。脊椎动物的DNA甲基化至少需要四种不同的DNA甲基转移酶，而黑腹果蝇仅利用一种类似Dnmt2的酶。这种显著差异引发了关于果蝇甲基化系统进化意义的问题。我们现已在拟暗果蝇和冈比亚按蚊的基因组序列中鉴定出类似Dnmt2的开放阅读框。这些基因是其各自基因组中唯一的候选DNA甲基转移酶。与Dnmt2蛋白的催化活性一致，我们还能证明这些物种的基因组DNA中存在低水平但显著的DNA甲基化。最后，我们还在其他几种果蝇物种中检测到高度保守的类似Dnmt2的开放阅读框以及相应的DNA甲基化，这表明Dnmt2介导的DNA甲基化在相当长的进化距离中得以保留。
