Perrotta G, Regina T M, Ceci L R, Quagliariello C
Dipartimento di Biologia Cellulare, Università della Calabria, Arcavacata di Rende, Italy.
Mol Gen Genet. 1996 Jun 12;251(3):326-37. doi: 10.1007/BF02172523.
The organization of the genes nad3 and rps12 has been investigated in the mitochondrial genome of two dicotyledonous plants - Helianthus and Magnolia - and one monocotyledonous plant (Allium). These plants all contain a complete rps12 gene downstream of the nad3 gene. This arrangement is thus highly conserved within angiosperms. The two genes are co-transcribed and the transcript is modified at several positions by RNA editing of the C to U-type, thus confirming that both genes encode functional proteins. Some 26, 35 and 27 editing events have been identified in the PCR-derived nad3-rps12 cDNA population from sunflower, Magnolia and onion, respectively. Editing of the nad3-rps12 transcript is thus more extensive in Magnolia than in the other angiosperms so far investigated and radically changes the genomically encoded polypeptide sequence. A novel species-specific codon modification was observed in Magnolia. Several homologous sites show differences in editing pattern among plant species. A C-to-U alteration is also found in the non-coding region separating the nad3 and rps12 genes in sunflower. The PCR-derived cDNA populations from the nad3-rps12 loci analysed were found to be differently edited. In addition the plant species show marked variations in the completeness of RNA editing, with only the Magnolia nad3 mRNA being edited fully.
在两种双子叶植物——向日葵和木兰，以及一种单子叶植物（葱属）的线粒体基因组中，对基因nad3和rps12的组织情况进行了研究。这些植物在nad3基因下游均含有完整的rps12基因。因此，这种排列在被子植物中高度保守。这两个基因共同转录，转录本在几个位置通过C到U型的RNA编辑进行修饰，从而证实这两个基因都编码功能蛋白。分别在来自向日葵、木兰和洋葱的PCR扩增得到的nad3 - rps12 cDNA群体中，鉴定出约26、35和27个编辑事件。因此，木兰中nad3 - rps12转录本的编辑比迄今为止研究的其他被子植物更为广泛，并且从根本上改变了基因组编码的多肽序列。在木兰中观察到一种新的物种特异性密码子修饰。几个同源位点在不同植物物种间的编辑模式存在差异。在向日葵中，分隔nad3和rps12基因的非编码区也发现了C到U的改变。分析发现，来自nad3 - rps12位点的PCR扩增得到的cDNA群体编辑方式不同。此外，不同植物物种在RNA编辑的完整性方面表现出显著差异，只有木兰的nad3 mRNA被完全编辑。
