Schock I, Maréchal-Drouard L, Marchfelder A, Binder S
Allgemeine Botanik, Universität Ulm, Germany.
Mol Gen Genet. 1998 Mar;257(5):554-60. doi: 10.1007/s004380050681.
The genes encoding pea and potato mitochondrial tRNAGly and pea mitochondrial tRNASer(GCU) were analyzed with particular respect to their expression. Secondary-structure models deduced from the identical potato and pea tRNAGly gene sequences revealed A7:C66 mismatches in the seventh base pair at the base of the acceptor stems of both tRNAs. Sequence analyses of tRNAGly cDNA clones showed that these mispairings are not corrected by C66 to U66 conversions, as observed in plant mitochondrial tRNAPhe. Likewise, a U6:C67 mismatch identified in the acceptor stem of the pea tRNASer(GCU) is not altered by RNA editing to a mismatched U:U pair, which is created by RNA editing in Oenothera mitochondrial tRNACys. In vitro processing reactions with the respective tRNAGly and tRNASer(GCU) precursors show that such conversions are not necessary for 5' and 3' end maturation of these tRNAs. These results demonstrate that not all C:A (A:C) or U:C (C:U) mismatches in double-stranded regions of tRNAs are altered by RNA editing. An RNA editing event in plant mitochondrial tRNAs is thus not generally indicated by the presence of a mismatch but may depend on additional parameters.
对编码豌豆和马铃薯线粒体甘氨酸tRNA以及豌豆线粒体丝氨酸tRNA（GCU）的基因进行了分析，特别关注它们的表达情况。从相同的马铃薯和豌豆甘氨酸tRNA基因序列推导出来的二级结构模型显示，两种tRNA的受体茎基部的第七个碱基对中存在A7:C66错配。甘氨酸tRNA cDNA克隆的序列分析表明，这些错配并未像在植物线粒体苯丙氨酸tRNA中观察到的那样通过C66到U66的转换得到校正。同样，在豌豆丝氨酸tRNA（GCU）的受体茎中鉴定出的U6:C67错配也没有通过RNA编辑改变为错配的U:U对，而这种错配的U:U对是在月见草线粒体半胱氨酸tRNA中通过RNA编辑产生的。用各自的甘氨酸tRNA和丝氨酸tRNA（GCU）前体进行的体外加工反应表明，这种转换对于这些tRNA的5'和3'末端成熟并非必需。这些结果表明，并非tRNA双链区域中的所有C:A（A:C）或U:C（C:U）错配都会通过RNA编辑改变。因此，植物线粒体tRNA中的RNA编辑事件通常并非由错配的存在所表明，而是可能取决于其他参数。
