An RNA-dependent RNA polymerase is required for paramutation in maize
An RNA-dependent RNA polymerase is required for paramutation in maize
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DOI：
10.1038/nature04884
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发表时间：
2006-07-20
期刊：
影响因子：
64.8
通讯作者：
Chandler, Vicki L.
中科院分区：
文献类型：
--
作者：
Alleman, Mary;Sidorenko, Lyudmila;Chandler, Vicki L.
Paramutation是表观遗传信息的等位基因依赖性转移，其导致一个等位基因被另一个等位基因遗传沉默（1）。玉米b1基因座的平行突变是由独特的串联重复序列介导的，这些串联重复序列以反式方式进行通信，以建立和维持减数分裂遗传的转录沉默（2）。mop 1（副突变介体1）基因是副突变所必需的（3），mop 1突变会重新激活沉默的Mutator元件（4）。携带mop 1基因突变的植物也表现出多效性发育表型（3）。在这里，我们报告了mop 1的图位克隆，mop 1是一种RNA依赖性RNA聚合酶基因（RDRP），与植物中的RDRP最相似，与靶向染色质的短干扰RNA（siRNA）的产生有关（5，6）。核运行的分析表明，所需的串联重复b1 paramutation转录从两条链，但siRNA没有检测到。我们建议，mop 1 RDRP是必需的，以维持一个阈值水平的重复RNA，其功能在反式建立和维持与副突变相关的遗传染色质状态。
Paramutation is an allele-dependent transfer of epigenetic information, which results in the heritable silencing of one allele by another(1). Paramutation at the b1 locus in maize is mediated by unique tandem repeats that communicate in trans to establish and maintain meiotically heritable transcriptional silencing(2). The mop1 ( mediator of paramutation1) gene is required for paramutation(3), and mop1 mutations reactivate silenced Mutator elements(4). Plants carrying mutations in the mop1 gene also stochastically exhibit pleiotropic developmental phenotypes(3). Here we report the map-based cloning of mop1, an RNA-dependent RNA polymerase gene (RDRP), most similar to the RDRP in plants that is associated with the production of short interfering RNA ( siRNA) targeting chromatin(5,6). Nuclear run-on assays reveal that the tandem repeats required for b1 paramutation are transcribed from both strands, but siRNAs were not detected. We propose that the mop1 RDRP is required to maintain a threshold level of repeat RNA, which functions in trans to establish and maintain the heritable chromatin states associated with paramutation.