Atypical RNA polymerase subunits required for RNA-directed DNA methylation
Atypical RNA polymerase subunits required for RNA-directed DNA methylation
复制标题
DOI：
10.1038/ng1580
复制
发表时间：
2005-07-01
期刊：
影响因子：
30.8
通讯作者：
Matzke, AJM
中科院分区：
文献类型：
--
作者：
Kanno, T;Huettel, B;Matzke, AJM
RNA定向DNA甲基化是细胞核中几种RNA干扰介导的途径之一(1)，已在植物（2,3）和人类细胞（4,5）中得到证实。尽管在鉴定DNA甲基化所需的DNA甲基化酶、组蛋白修饰酶和RNA干扰蛋白方面取得了进展(1)，但其机制仍不完全清楚。我们筛选了拟南芥中RNA定向DNA甲基化和转基因启动子沉默缺陷的突变体，并鉴定了三个drd互补基团(6)。DRD1是一种SNF2样蛋白(6)，是RNA定向从头甲基化所必需的。我们在此报道，DRD2和DRD3分别对应于植物特有的第四类DNA依赖性RNA聚合酶（聚合酶IV）的第二大亚基和最大亚基。DRD3是NRPD1a或SDE4的功能多样化同源物，在转录后基因沉默缺陷突变体的单独筛选中发现（7,8）。在所有三种drd突变体中观察到的相同的DNA甲基化模式表明，drd蛋白合作为RNA定向的从头甲基化创造了一个底物。
RNA- directed DNA methylation, one of several RNA interference - mediated pathways in the nucleus(1), has been documented in plants(2,3) and in human cells(4,5). Despite progress in identifying the DNA methyltransferases, histone-modifying enzymes and RNA interference proteins needed for RNA- directed DNA methylation(1), the mechanism remains incompletely understood. We screened for mutants defective in RNA- directed DNA methylation and silencing of a transgene promoter in Arabidopsis thaliana and identified three drd complementation groups(6). DRD1 is a SNF2- like protein(6) required for RNA- directed de novo methylation. We report here that DRD2 and DRD3 correspond to the second- largest subunit and largest subunit, respectively, of a fourth class of DNA- dependent RNA polymerase ( polymerase IV) that is unique to plants. DRD3 is a functionally diversified homolog of NRPD1a or SDE4, identified in a separate screen for mutants defective in post- transcriptional gene silencing(7,8). The identical DNA methylation patterns observed in all three drd mutants suggest that DRD proteins cooperate to create a substrate for RNA- directed de novo methylation.