Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany.
Plant J. 2010 Feb 1;61(3):446-55. doi: 10.1111/j.1365-313X.2009.04076.x. Epub 2009 Nov 16.
Post-transcriptional RNA editing in flowering plant mitochondria alters several hundred nucleotides from cytidine to uridine, mostly in mRNAs. To characterize the factors involved in RNA editing in plant mitochondria, we initiated a screen for nuclear mutants defective in RNA editing at specific sites. Here we identify the nuclear-encoded gene MEF11, which is involved in RNA editing of the three sites cox3-422, nad4-124 and ccb203-344 in Arabidopsis thaliana. A T-DNA insertion line of this gene was previously characterized as showing enhanced tolerance to the compound lovastatin, an inhibitor of the mevalonate pathway of isoprenoid biosynthesis. The mef11-1 mutant described here shows similar tolerance to lovastatin. Identification of the function of the MEF11 protein in site-specific mitochondrial RNA editing suggests indirect effects of retrograde signalling from mitochondria to the cytoplasm to evoke alteration of the mevalonate pathway. The editing sites cox3-422 and ccb203-344 each alter amino acids that are conserved in the respective proteins, while the nad4-124 site is silent. The single amino acid change in the mef11-1 mutant occurs in the second pentatricopeptide repeat, suggesting that this motif is required for site-specific RNA editing.
植物线粒体中转录后 RNA 编辑将几百个核苷酸从胞嘧啶变为尿嘧啶，主要发生在 mRNA 中。为了鉴定参与植物线粒体 RNA 编辑的因子，我们开始筛选特定位点 RNA 编辑缺陷的核突变体。在这里，我们鉴定了一个核编码基因 MEF11，该基因参与拟南芥 cox3-422、nad4-124 和 ccb203-344 三个位点的 RNA 编辑。该基因的 T-DNA 插入系先前被表征为对 lovastatin（异戊烯基生物合成的甲羟戊酸途径的抑制剂）表现出增强的耐受性。这里描述的 mef11-1 突变体表现出对 lovastatin 的类似耐受性。MEF11 蛋白在特定线粒体 RNA 编辑位点的功能鉴定表明，线粒体到细胞质的逆行信号的间接影响，引发甲羟戊酸途径的改变。cox3-422 和 ccb203-344 两个编辑位点都改变了各自蛋白中保守的氨基酸，而 nad4-124 位点是沉默的。mef11-1 突变体中的单个氨基酸变化发生在第二个五肽重复序列中，表明该基序是特异性 RNA 编辑所必需的。
