SRA- and SET-domain-containing proteins link RNA polymerase V occupancy to DNA methylation.
SRA- and SET-domain-containing proteins link RNA polymerase V occupancy to DNA methylation.
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作者：
拟南芥中RNA指导的DNA甲基化（RdDM）依赖于RNA聚合酶IV（Pol IV）上游合成24个核苷酸的小干扰RNA（siRNA）和Pol V下游合成非编码转录物。Pol V转录物被认为与siRNA相互作用，然后募集结构域重排甲基转移酶2（DRM 2）使DNA甲基化。SU（VAR）3-9同系物SUVH 2和SUVH 9在该下游步骤中起作用，但其作用机制尚不清楚。在这里，我们表明，全基因组Pol V与染色质的关联冗余地需要，SUV H2和SUV H9。尽管SUV H2和SUV H9类似于组蛋白甲基转移酶，但晶体结构揭示SUV H9缺乏肽-底物结合裂缝，并且缺乏正常催化所必需的适当形成的S-腺苷甲硫氨酸（SAM）结合口袋，这与这些蛋白质缺乏甲基转移酶活性一致。SUV H2和SUV H9都含有能够结合甲基化DNA的SET-和RING-相关（SRA）结构域，表明它们通过DNA甲基化来募集Pol V。与该模型一致，DNA甲基转移酶1（MET 1）的突变导致DNA甲基化丧失，Pol V在其正常位置几乎完全丧失，并且Pol V重新分布到变得高度甲基化的位点。此外，用锌指将SUV H2拴系到未甲基化位点足以募集Pol V并建立DNA甲基化和基因沉默。这些结果表明，Pol V通过甲基-DNA结合SUVH 2和SUVH 9蛋白被招募到DNA甲基化，并且我们的机制发现表明了一种选择性靶向植物基因组区域进行表观遗传沉默的方法。
RNA-directed DNA methylation (RdDM) in Arabidopsis thaliana depends on the upstream synthesis of 24-nucleotide small interfering RNAs (siRNAs) by RNA POLYMERASE IV (Pol IV) and downstream synthesis of non-coding transcripts by Pol V. Pol V transcripts are thought to interact with siRNAs which then recruit DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2) to methylate DNA. The SU(VAR)3-9 homologs SUVH2 and SUVH9 act in this downstream step but the mechanism of their action is unknown. Here we show that genome-wide Pol V association with chromatin redundantly requires, SUVH2 and SUVH9. Although SUVH2 and SUVH9 resemble histone methyltransferases a crystal structure reveals that SUVH9 lacks a peptide-substrate binding cleft and lacks a properly formed S-adenosyl methionine (SAM) binding pocket necessary for normal catalysis, consistent with a lack of methyltransferase activity for these proteins. SUVH2 and SUVH9 both contain SET- and RING-ASSOCIATED (SRA) domains capable of binding methylated DNA, suggesting that they function to recruit Pol V through DNA methylation. Consistent with this model, mutation of DNA METHYLTRANSFERASE 1 (MET1) causes loss of DNA methylation, a nearly complete loss of Pol V at its normal locations, and redistribution of Pol V to sites that become hypermethylated. Furthermore, tethering SUVH2 with a zinc finger to an unmethylated site is sufficient to recruit Pol V and establish DNA methylation and gene silencing. These results suggest that Pol V is recruited to DNA methylation through the methyl-DNA binding SUVH2 and SUVH9 proteins, and our mechanistic findings suggest a means for selectively targeting regions of plant genomes for epigenetic silencing.
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影响因子：
4.5
作者：
Johnson LM;Law JA;Khattar A;Henderson IR;Jacobsen SE
通讯作者：
Jacobsen SE
影响因子：
5.8
作者：
Gouet, P;Courcelle, E;Métoz, F
通讯作者：
Métoz, F
将RNA定向DNA甲基化的两步募集到串联重复序列。
影响因子：
9.8
作者：
Chan, Simon W-L;Zhang, Xiaoyu;Bernatavichute, Yana V;Jacobsen, Steven E
通讯作者：
Jacobsen, Steven E
DOI：
10.1107/s0907444909052925
发表时间：
2010-02
期刊：
Acta crystallographica. Section D, Biological crystallography
影响因子：
--
作者：
Adams PD;Afonine PV;Bunkóczi G;Chen VB;Davis IW;Echols N;Headd JJ;Hung LW;Kapral GJ;Grosse-Kunstleve RW;McCoy AJ;Moriarty NW;Oeffner R;Read RJ;Richardson DC;Richardson JS;Terwilliger TC;Zwart PH
通讯作者：
Zwart PH
影响因子：
4.5
作者：
Greenberg MV;Deleris A;Hale CJ;Liu A;Feng S;Jacobsen SE
通讯作者：
Jacobsen SE