The pea mitochondrial atp6: RNA editing and similarity of presequences in the Vicieae tribe

Abstract

The atp6 gene has been identified as a single-copy sequence in the mitochondrial genome of the pea. An unexpected finding concerns the atp6 5' extension which is known to be poorly conserved at the sequence level, even between closely related plant species. We have shown that the presequences of ATP6 from the pea and other species belonging to the Vicieae tribe of Fabaceae (broad bean, hairy vetch) share a sequence similarity which extends to long 5' untranslated transcript termini. The reason for the observed conservation is not clear but may simply reflect the close phylogenetic relationship of species from the Vicieae tribe. The result of editing analysis indicates the occurrence of fully and partially edited transcripts of atp6 in the pea mitochondria. The majority of the editing sites are targeted to the last transmembrane domain of the pea ATP6, important in proton translocation and interactions with other subunits of ATP synthase.

The 5′-leader sequence of sugar beet mitochondrial atp6 encodes a novel polypeptide that is characteristic of Owen cytoplasmic male sterility

“…In the Owen mitochondria, the preSatp6 and Satp6 coding regions constitute a single continuous ORF. An in-frame ORF preceding the conserved atp6-core sequence is commonly found in higher plants Marienfeld et al 1996;Onodera et al 1999;Gibala et al 2004), but nothing further is known about the expression and function of this presequence. The present study thus provides the first evidence that the contiguous preSatp6 and Satp6 coding sequences are co-transcribed to give an RNA from which the mature preSATP6 polypeptide is actually translated.…”

“…The atp6 reading frame has a conserved core sequence (comprising 249-252 codons) that begins with the sequence SerPro-Leu (Gibala et al 2004). However, this is preceded by an in-frame ORF of varying length (5-389 codons) that shows virtually no sequence conservation between species, making it difficult to confidently infer a role for it.…”

Editing Sites in Transcript of Mitochondrial <I>atp6</I> Gene of Male Sterile Line with <I>Aegilops kotschyi</I> Cytoplasm in Wheat

“…作 物 学 报 第 36 卷 与向日葵 CMS 形成有直接关系 [3] 。水稻的 orf79 与 atp6 基因同时转录, 编码一个细胞毒素肽, 且转 orf79 的植株 能产生败育的花粉, 与水稻的 CMS 直接相关 [4] 。 Rathburn 等 [5] 发现在 T 型小麦不育系、可育系和相应的恢复系中, 线粒体 coxI 基因的上游存在一个嵌合基因 orf256, 编码 一种 7 kD 的蛋白, 仅在 T 型 CMS 系中表达 [6] 。目前, 还 缺乏 orf256/coxI 与小麦雄性不育相关的直接证据。 近年研究表明, CMS 与高等植物线粒体基因的 RNA 编辑有重要关系 [7][8] 。在 RNA 编辑中由于碱基的插入、缺 失或替代, 改变了初始模板的编码特性, 导致转录产物 的核苷酸序列不能忠实地反应模板 DNA 的一级结构, 它 是线粒体基因组产生功能蛋白必不可少的步骤。 线粒体基 因发生 RNA 编辑后, 这些非正确或不充分编辑的产物可 能会导致线粒体功能不能正常发挥而形成 CMS [9] 。目前, 在 CMS 作物中 atp6 基因编辑最为关注。在高粱花药中, 不育系线粒体 atp6 基因的编辑频率明显降低 [10] , 除了恢复 基因, 任何核背景都不能恢复 atp6 转录本的编辑频率 [11] 。 汪静等 [12] 发现玉米线粒体功能基因 atp6 和 cox2 的 RNA 编辑在可育胞质中编辑频率高于在不育胞质中。豌豆的 atp6 基因 RNA 编辑也与其 CMS 相关 [13] 。 有研究认为 atp6 和 atp9 基因位点及它们上、 下游 DNA 序列的变化与 CMS 关系密切 [14][15] 。赵婷等 [16] 通过分析烟草 atp6 基因的 SNP,…”