Substitutional editing of Heterocapsa triquetra chloroplast transcripts and a folding model for its divergent chloroplast 16S rRNA
Substitutional editing of Heterocapsa triquetra chloroplast transcripts and a folding model for its divergent chloroplast 16S rRNA
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DOI：
10.1016/j.gene.2009.04.006
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发表时间：
2009-08-01
期刊：
影响因子：
3.5
通讯作者：
Green, Beverley R.
中科院分区：
文献类型：
--
作者：
Dang, Yunkun;Green, Beverley R.
替代编辑通过在RNA水平上改变或修改碱基来增加基因组的可塑性。在这项研究中，我们对甲藻的10个成熟叶绿体mRNAs、叶绿体16S rRNA和部分叶绿体23S rRNA进行了测序，发现了多种类型的替代编辑，其中以A-G编辑为主。对mRNAs的A-G编辑将两个不寻常的AUA起始密码子转化为常规的AUG起始密码子，但三个AUA起始密码子没有被编辑，这表明这个甲藻类叶绿体有三个可能的起始密码子：AUG、AUA和UUG。为了分析编辑对rRNA的影响，我们基于大肠杆菌模型对16S rRNA的二级结构进行了计算预测。在二级结构保存完好的区域有20个编辑点，其中11个用其他模式恢复了保护。此外，A-to-G编辑位点经常出现在环区而不是双链区，这表明甲藻类叶绿体中的A-to-G编辑机制不同于动物核A-to-I(G)编辑机制。通过比较方法得到的编辑后的16S rRNA模型与其他16S rRNA具有保守的二级结构元素，尽管其一级序列非常不同，支持其作为叶绿体核糖体功能成分的作用。(C)2009爱思唯尔B.V.保留所有权利。
Substitutional editing increases genomic plasticity by changing or modifying bases at the RNA level. In this study we sequenced 10 mature chloroplast mRNAs, the chloroplast 16S rRNA and a partial chloroplast 23S rRNA from the dinoflagellate Heterocapsa triquetra, and found multiple types of substitutional editing, with A-to-G editing predominating. A-to-G editing of mRNAs converts two unusual AUA start codons into conventional AUG start codons, but three AUA start codons are not edited, showing that this dinoflagellate chloroplast has three possible start codons: AUG, AUA and UUG. To analyze the editing effects on rRNAs, we computationally predicted the secondary structure of the 16S rRNA based on the E coli model. There are twenty editing sites in well-conserved regions of the secondary structure and eleven out of them restore conservation with other models. Moreover, A-to-G editing sites are frequently found in loop regions rather than double-stranded regions, suggesting that the A-to-G editing mechanism in dinoflagellate chloroplasts is different from that responsible for animal nuclear A-to-I(G) editing. The model of the edited 16S rRNA derived by the comparative method shares conserved secondary structural elements with other 16S rRNAs in spite of its very divergent primary sequence, supporting its role as a functional component of the chloroplast ribosome. (C) 2009 Elsevier B.V. All rights reserved.