Tandem repeats upstream of the Arabidopsis endogene SDC recruit non-CG DNA methylation and initiate siRNA spreading
Tandem repeats upstream of the Arabidopsis endogene SDC recruit non-CG DNA methylation and initiate siRNA spreading
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DOI：
10.1101/gad.1667808
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发表时间：
2008-06-15
影响因子：
10.5
通讯作者：
Jacobsen, Steven E.
中科院分区：
文献类型：
--
作者：
Henderson, Ian R.;Jacobsen, Steven E.
植物使用siRNAs来针对对称的CG和非对称的(CHG和CHH)序列背景下的胞嘧啶DNA甲基化。DNA甲基化和siRNA簇最常与拟南芥基因组中的转座子重叠。然而，相当数量的蛋白质编码基因也显示出启动子DNA甲基化，这可以用来抑制它们的表达。在drm1、drm2、cmt3三个突变体中，大多数非CG DNA甲基化缺失导致发育表型。我们鉴定了导致这些表型的基因是drm1drm2 cmt3(SDC)的抑制子，它编码一个F-box蛋白，具有7个启动子串联重复序列。SDC重复序列显示了组蛋白甲基化和siRNAs冗余指导的非CG DNA甲基化的独特沉默要求，并显示了siRNAs的扩散和甲基化超出重复区域。除了揭示拟南芥DNA甲基化控制的复杂性外，SDC还对植物基因组如何利用基因沉默来抑制内源基因具有重要的意义。
Plants use siRNAs to target cytosine DNA methylation to both symmetrical CG and nonsymmetrical (CHG and CHH) sequence contexts. DNA methylation and siRNA clusters most frequently overlap with transposons in the Arabidopsis thaliana genome. However, a significant number of protein-coding genes also show promoter DNA methylation, and this can be used to silence their expression. Loss of the majority of non-CG DNA methylation in drm1 drm2 cmt3 triple mutants leads to developmental phenotypes. We identified the gene responsible for these phenotypes as SUPPRESSOR OF drm1 drm2 cmt3 (SDC), which encodes an F-box protein and possesses seven promoter tandem repeats. The SDC repeats show a unique silencing requirement for non-CG DNA methylation directed redundantly by histone methylation and siRNAs, and display spreading of siRNAs and methylation beyond the repeated region. In addition to revealing the complexity of DNA methylation control in A. thaliana, SDC has important implications for how plant genomes utilize gene silencing to repress endogenous genes.