required to maintain repression2 Is a Novel Protein That Facilitates Locus-Specific Paramutation in Maize
required to maintain repression2 Is a Novel Protein That Facilitates Locus-Specific Paramutation in Maize
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DOI：
10.1105/tpc.112.097618
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发表时间：
2012-05-01
期刊：
影响因子：
11.6
通讯作者：
Hollick, Jay B.
中科院分区：
文献类型：
--
作者：
Barbour, Joy-El R.;Liao, Irene T.;Hollick, Jay B.
减数分裂遗传的表观遗传变化的基因调控被称为副突变，促进了知之甚少的反式同源物的相互作用。影响玉米（Zea mays）中副突变的突变鉴定了积累24-核苷酸RNA所需的组分。这些组分中的一些具有拟南芥直向同源物，其是RNA指导的DNA甲基化（RdDM）途径的一部分。目前尚不清楚小RNA是否真的介导副突变，以及迄今为止鉴定的玉米特异性分子是否定义了与RdDM不同的机制。在这里，我们确定了一种新的蛋白质所需的玉米紫色plant 1基因座的副突变。这需要保持阻遏2（RMR 2）蛋白代表预测蛋白质的植物特异性进化枝的创始成员。我们表明，RMR 2是必要的转录抑制在Pl 1-Rhoades单倍型，积累24个核苷酸的RNA种类，并维持5-甲基胞嘧啶模式不同的RNA聚合酶IV。遗传测试表明，RMR 2是不需要的paramutation发生在red 1基因座。这些结果区分在特定的单倍型的副突变型机制。蛋白质的RMR 2进化枝为理解高等植物中表观基因组控制的多样性提供了一个新的切入点。
Meiotically heritable epigenetic changes in gene regulation known as paramutations are facilitated by poorly understood trans-homolog interactions. Mutations affecting paramutations in maize (Zea mays) identify components required for the accumulation of 24-nucleotide RNAs. Some of these components have Arabidopsis thaliana orthologs that are part of an RNA-directed DNA methylation (RdDM) pathway. It remains unclear if small RNAs actually mediate paramutations and whether the maize-specific molecules identified to date define a mechanism distinct from RdDM. Here, we identify a novel protein required for paramutation at the maize purple plant1 locus. This required to maintain repression2 (RMR2) protein represents the founding member of a plant-specific clade of predicted proteins. We show that RMR2 is required for transcriptional repression at the Pl1-Rhoades haplotype, for accumulation of 24-nucleotide RNA species, and for maintenance of a 5-methylcytosine pattern distinct from that maintained by RNA polymerase IV. Genetic tests indicate that RMR2 is not required for paramutation occurring at the red1 locus. These results distinguish the paramutation-type mechanisms operating at specific haplotypes. The RMR2 clade of proteins provides a new entry point for understanding the diversity of epigenomic control operating in higher plants.