n nnnIn mitochondria of higher plants, the majority of 5' terminiof mature mRNAs are generated posttranscriptionally. To gaininsight into this process, we analyzed a natural 5' end polymorphismin the species Arabidopsis thaliana. This genetic approach identifiedthe nuclear gene At1g62670, encoding a pentatricopeptide repeatprotein. The functional importance of this mitochondrial restorerof fertility-like protein, designated RNA PROCESSING FACTOR2(RPF2), is confirmed by the analysis of a respective T-DNA knockoutmutant and its functional restoration by in vivo complementation.RPF2 fulfills two functions: it is required for the generationof a distinct 5' terminus of transcripts of subunit 9 of theNADH DEHYDROGENASE complex (nad9) and it determines the efficiencyof 5' end formation of the mRNAs for subunit 3 of the CYTOCHROMEC OXIDASE (cox3), the latter also being influenced by mitochondrialDNA sequences. Accordingly, recombinant RPF2 protein directlybinds to a nad9 mRNA fragment in vitro. Two-dimensional gelelectrophoresis and immunodetection analyses reveal that altered5' processing does not influence accumulation of the nad9 andcox3 polypeptides. In accessions C24, Oystese-1, and Yosemite-0,different inactive RPF2 alleles exist, demonstrating the variabilityof this gene in Arabidopsis. The identification of RPF2 is amajor step toward the characterization of 5' mRNA processingin mitochondria of higher plants.展开▼
机译：ABSTRACTn n
n TOP n <字体颜色= 464c53>抽象 n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n n nnn在高等植物的线粒体中，大部分5'末端 re mRNA在转录后产生。为了了解此过程，我们分析了拟南芥（Arabidopsis thaliana）物种的天然5'端多态性 。这种遗传方法鉴定了 核基因At1g62670，该基因编码五肽重复序列 蛋白。通过分析相应的T-DNA敲除，证实了这种可育性蛋白的线粒体恢复子 的功能重要性，命名为RNA PROCESSING FACTOR2 （RPF2）。 突变体及其通过体内互补的功能恢复。 RPF2具有两个功能：它是生成亚基9转录本的独特5'末端的 所必需的SUP> NADH脱氢酶复合物（ nad9 ）的合成，并确定CYTOCHROME > C氧化酶（ cox3 ），后者也受到线粒体 DNA序列的影响。因此，重组RPF2蛋白直接 在体外与 nad9 mRNA片段结合。二维凝胶 电泳和免疫检测分析表明，改变的 5'处理不会影响 nad9 和 的积累 cox3 多肽。在保藏号C24，Oystese-1和Yosemite-0中，存在 个不同的非活性 RPF2 等位基因，证明了该基因在中的变异性 。拟南芥 RPF2 的鉴定是 表征高等植物线粒体中5'mRNA加工 的重要步骤。展开▼
