Abstract

Beyond their key role in translation, cytosolic transfer RNAs (tRNAs) are involved in a wide range of other biological processes. Nuclear tRNA genes (tDNAs) are transcribed by the RNA polymerase III (RNAP III) and cis-elements, trans-factors as well as genomic features are known to influence their expression. In Arabidopsis, besides a predominant population of dispersed tDNAs spread along the 5 chromosomes, some clustered tDNAs have been identified. Here, we demonstrate that these tDNA clusters are transcriptionally silent and that pathways involved in the maintenance of DNA methylation play a predominant role in their repression. Moreover, we show that clustered tDNAs exhibit repressive chromatin features whilst their dispersed counterparts contain permissive euchromatic marks. This work demonstrates that both genomic and epigenomic contexts are key players in the regulation of tDNAs transcription. The conservation of most of these regulatory processes suggests that this pioneering work in Arabidopsis can provide new insights into the regulation of RNA Pol III transcription in other organisms, including vertebrates.

中文翻译：

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拟南芥中聚集的tRNA基因的表观遗传沉默。

摘要

除了它们在翻译中的关键作用之外，胞质转移RNA（tRNA）还参与了许多其他生物学过程。核tRNA基因（tDNA）被RNA聚合酶III（RNAP III）和顺式元素转录已知-因子和基因组特征会影响它们的表达。在拟南芥中，除了主要的沿5条染色体分布的分散tDNA群体外，还发现了一些成簇的tDNA。在这里，我们证明了这些tDNA簇在转录上是沉默的，并且参与维持DNA甲基化的途径在其抑制中起主要作用。此外，我们表明，聚簇的tDNA表现出抑制性染色质特征，而其分散的对应物包含允许的常染色体标记。这项工作表明，基因组和表观基因组环境都是tDNA转录调控的关键因素。