Kanno Tatsuo, Aufsatz Werner, Jaligot Estelle, Mette Michael Florian, Matzke Marjori, Matzke Antonius J M
Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, UZA2, Pharmazie Zentrum, Althanstrasse 14/2D-541, 1090 Vienna, Austria.
EMBO Rep. 2005 Jul;6(7):649-55. doi: 10.1038/sj.embor.7400446.
DRD1 is a SNF2-like protein previously identified in a screen for mutants defective in RNA-directed DNA methylation of a seed promoter in Arabidopsis. Although the initial study established a role for DRD1 in RNA-directed DNA methylation, it did not address whether DRD1 is needed for de novo or maintenance methylation, or whether it is required for methylation of other target sequences. We show here that DRD1 is essential for RNA-directed de novo methylation and acts on different target promoters. In addition, an unanticipated role for DRD1 in erasure of CG methylation was shown when investigating maintenance methylation after segregating away the silencing trigger. DRD1 is unique among known SNF2-like proteins in facilitating not only de novo methylation of target sequences in response to RNA signals, but also loss of methylation when the silencing inducer is withdrawn. The opposing roles of DRD1 could contribute to the dynamic regulation of DNA methylation.
DRD1是一种类似SNF2的蛋白质，先前在对拟南芥种子启动子RNA定向DNA甲基化缺陷突变体的筛选中被鉴定出来。尽管最初的研究确定了DRD1在RNA定向DNA甲基化中的作用，但并未探讨DRD1对于从头甲基化或维持甲基化是否必要，也未涉及它对于其他靶序列甲基化是否必需。我们在此表明，DRD1对于RNA定向从头甲基化至关重要，并且作用于不同的靶启动子。此外，在分离沉默触发因子后研究维持甲基化时，发现了DRD1在消除CG甲基化方面的一个意外作用。在已知的类似SNF2的蛋白质中，DRD1独一无二，它不仅能促进靶序列响应RNA信号的从头甲基化，还能在沉默诱导剂去除时导致甲基化缺失。DRD1的这两种相反作用可能有助于DNA甲基化的动态调控。
