College of Life Sciences, Shaanxi Normal University, Xi'an 710062, China.
J Integr Plant Biol. 2011 Dec;53(12):961-70. doi: 10.1111/j.1744-7909.2011.01082.x.
RNA editing is a post-transcriptional process that results in modifications of ribonucleotides at specific locations. In land plants editing can occur in both mitochondria and chloroplasts and most commonly involves C-to-U changes, especially in seed plants. Using prediction and experimental determination, we investigated RNA editing in 40 protein-coding genes from the chloroplast genome of Cycas taitungensis. A total of 85 editing sites were identified in 25 transcripts. Comparison analysis of the published editotypes of these 25 transcripts in eight species showed that RNA editing events gradually disappear during plant evolution. The editing in the first and third codon position disappeared quicker than that in the second codon position. ndh genes have the highest editing frequency while serine and proline codons were more frequently edited than the codons of other amino acids. These results imply that retained RNA editing sites have imbalanced distribution in genes and most of them may function by changing protein structure or interaction. Mitochondrion protein-coding genes have three times the editing sites compared with chloroplast genes of Cycas, most likely due to slower evolution speed.
RNA 编辑是一种转录后过程，导致特定位置的核糖核苷酸发生修饰。在陆地植物中，编辑可以发生在线粒体和叶绿体中，最常见的是 C 到 U 的变化，特别是在种子植物中。我们使用预测和实验确定的方法，研究了台湾苏铁叶绿体基因组中 40 个编码蛋白基因的 RNA 编辑。在 25 个转录本中鉴定出了 85 个编辑位点。对这 25 个转录本在 8 个物种中的已发表编辑型的比较分析表明，RNA 编辑事件在植物进化过程中逐渐消失。第一和第三个密码子位置的编辑比第二个密码子位置的编辑消失得更快。ndh 基因的编辑频率最高，而丝氨酸和脯氨酸密码子比其他氨基酸的密码子更容易被编辑。这些结果表明，保留的 RNA 编辑位点在基因中分布不平衡，其中大多数可能通过改变蛋白质结构或相互作用来发挥作用。与台湾苏铁的叶绿体基因相比，线粒体蛋白编码基因的编辑位点多出三倍，这很可能是由于进化速度较慢所致。
