Lu M Z, Szmidt A E, Wang X R
Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå.
Plant Mol Biol. 1998 May;37(2):225-34. doi: 10.1023/a:1005972513322.
Sequence analysis of the mitochondrial coxI gene in eight gymnosperm species revealed a high rate of nonsynonymous nucleotide substitutions with a strong (98%) predominance of C-T substitutions. Further analysis of the corresponding coxI cDNA sequences showed that all the non-synonymous C-T changes in the coxI genomic DNA sequences were eliminated by RNA editing resulting in nearly identical mRNA (amino acid) sequences among the species. Pronounced variation in the number and location of edited sites was found among species. Most species had a relatively large number of edited sites (from 25 to 34). However, no RNA editing of the coxI sequence was found in Gingko biloba or Larix sibirica. The sequence composition of the investigated coxI fragment suggests that the coxI gene in G. biloba and L. sibirica originated from edited mitochondrial coxI transcripts by reverse transcription followed by insertion into the nuclear genome or back into the mitochondrial genome. Our results also demonstrate that where there are a large number of edited sites, RNA editing can accelerate the divergence of nucleotide sequences among species.
对八个裸子植物物种的线粒体细胞色素氧化酶亚基I（coxI）基因进行序列分析发现，非同义核苷酸替换率很高，其中C-T替换占主导地位（98%）。对相应的coxI cDNA序列进行进一步分析表明，coxI基因组DNA序列中所有非同义C-T变化都通过RNA编辑消除，导致这些物种之间的mRNA（氨基酸）序列几乎相同。在不同物种中发现编辑位点的数量和位置存在显著差异。大多数物种有相对较多的编辑位点（25到34个）。然而，在银杏或西伯利亚落叶松中未发现coxI序列的RNA编辑。所研究的coxI片段的序列组成表明，银杏和西伯利亚落叶松中的coxI基因起源于经过编辑的线粒体coxI转录本，通过逆转录，随后插入核基因组或回到线粒体基因组中。我们的结果还表明，在存在大量编辑位点的情况下，RNA编辑可以加速物种间核苷酸序列的分化。
