Neckermann K, Zeltz P, Igloi G L, Kössel H, Maier R M
Institut für Biologie III, Universität Freiburg, Germany.
Gene. 1994 Sep 2;146(2):177-82. doi: 10.1016/0378-1119(94)90290-9.
Open reading frames (ORFs), encoded by the plastid genomes of tobacco, liverwort, rice and maize were aligned with a view to studying the conservation of translational start and stop codons created by RNA editing of homologous genes. It became evident that most of the homologous ORFs have conserved translation start and stop signals at the gene level. However, some of the ORFs show differences with respect to extensions of their 3' and 5' terminal regions. For example, the proposed N-termini of the ndhD-encoded peptides from different plant species are very variable in length and amino-acid composition. Sequence analysis of ndhD and the corresponding cDNA shows that editing of an ACG triplet in tobacco, spinach and snapdragon leads to the creation of an AUG codon, corresponding to the start codon in other species. Conservation of translational start codons of plastome-encoded genes can, therefore, be achieved by editing of transcripts, and the definition of plastome-encoded ORFs must take potential editing events into consideration.
为了研究同源基因RNA编辑产生的翻译起始和终止密码子的保守性，对烟草、地钱、水稻和玉米质体基因组编码的开放阅读框（ORF）进行了比对。很明显，大多数同源ORF在基因水平上具有保守的翻译起始和终止信号。然而，一些ORF在其3'和5'末端区域的延伸方面存在差异。例如，不同植物物种中由ndhD编码的肽的预测N末端在长度和氨基酸组成上变化很大。对ndhD和相应cDNA的序列分析表明，烟草、菠菜和金鱼草中ACG三联体的编辑导致了AUG密码子的产生，这与其他物种中的起始密码子相对应。因此，质体基因组编码基因的翻译起始密码子的保守性可以通过转录本的编辑来实现，并且质体基因组编码的ORF的定义必须考虑潜在的编辑事件。
