Nuclear DYW-Type PPR Gene Families Diversify with Increasing RNA Editing Frequencies in Liverwort and Moss Mitochondria
Nuclear DYW-Type PPR Gene Families Diversify with Increasing RNA Editing Frequencies in Liverwort and Moss Mitochondria
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DOI：
10.1007/s00239-012-9486-3
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发表时间：
2012-02-01
影响因子：
3.9
通讯作者：
Knoop, Volker
中科院分区：
文献类型：
--
作者：
Ruedinger, Mareike;Volkmar, Ute;Knoop, Volker
陆地植物线粒体和叶绿体中的RNA编辑通过将胞苷定点转化为尿苷来改变转录序列。不同陆生植物分支之间的RNA编辑频率差异极大，从一些苔类植物的零到石蒜中的2000多个位置不等。最近，模式植物中独特的具有可变区延伸的五肽重复(PPR)蛋白(E/E+/Dyw)被确定为特异的编辑位点识别因子。这些PPR蛋白结构域的不同功能尚不清楚，尽管已经提出了Dyw结构域的脱氨酶功能。为了阐明陆地植物进化起源中的RNA编辑和dyw蛋白的多样性，我们使用最近开发的PREPACT程序(www.prepact.de)对100多种苔藓和苔藓的线粒体NAD5、NAD4和NAD2基因的编辑模式进行了研究，并典型地证实了在选定的类群中预测的RNA编辑位点。RNA编辑频率的极端变异性在苔藓和苔藓中都可以看到。只有极少的编辑存在于苔类植物Lejeunea cavifolia或Pogonatum urnigerum中，而高达20%的胞苷在地钱植物Haplomitrium mnioids或苔藓Takaki Lepidozioides中编辑。有趣的是，后者是在各自分支中很早就分枝的分类群。针对E/E+/dyw结构域的扩增和随后的随机克隆测序表明，与被子植物相比，苔藓植物中的dyw结构域高度保守，并与RNA编辑频率的多样性密切相关。我们认为Dyw蛋白在陆地植物起源的RNA编辑中起着关键作用。
RNA editing in mitochondria and chloroplasts of land plants alters transcript sequences by site-specific conversions of cytidines into uridines. RNA editing frequencies vary extremely between land plant clades, ranging from zero in some liverworts to more than 2,000 sites in lycophytes. Unique pentatricopeptide repeat (PPR) proteins with variable domain extension (E/E+/DYW) have recently been identified as specific editing site recognition factors in model plants. The distinctive functions of these PPR protein domain additions have remained unclear, although deaminase function has been proposed for the DYW domain. To shed light on diversity of RNA editing and DYW proteins at the origin of land plant evolution, we investigated editing patterns of the mitochondrial nad5, nad4, and nad2 genes in a wide sampling of more than 100 liverworts and mosses using the recently developed PREPACT program (www.prepact.de) and exemplarily confirmed predicted RNA editing sites in selected taxa. Extreme variability in RNA editing frequency is seen both in liverworts and mosses. Only few editings exist in the liverwort Lejeunea cavifolia or the moss Pogonatum urnigerum whereas up to 20% of cytidines are edited in the liverwort Haplomitrium mnioides or the moss Takakia lepidozioides. Interestingly, the latter are taxa that branch very early within their respective clades. Amplicons targeting the E/E+/DYW domains and subsequent random clone sequencing show DYW domains among bryophytes to be highly conserved in comparison with their angiosperm counterparts and to correlate well with RNA editing frequencies regarding their diversities. We propose that DYW proteins are the key players of RNA editing at the origin of land plants.