Maloney A P, Traynor P L, Levings C S, Walbot V
Department of Biological Sciences, Stanford University, CA 94305.
Curr Genet. 1989 Mar;15(3):207-12. doi: 10.1007/BF00435507.
By direct RNA mapping, we have identified the precise 5' end of the maize mitochondrial 26S rRNA. The 5' termini of the 26S rRNA are 17 and 18 nt downstream from the 5' end predicted by Dale et al. (1984) from homology between the maize rRNA and E. coli large subunit ribosomal RNA. In addition, we have discovered a larger 26S species, presumably a 26S precursor, and precisely mapped its 5' end. The maize mitochondrial rRNA genes are probably regulated by control regions that differ from those already characterized in other genomes: the maize mitochondrial 26S, 18S and 5S rRNAs lack sequences that resemble the promoter regions of genes from other mitochondria and bacteria. However, the mature and precursor rRNAs all contain a tetranucleotide, AAUC, at their 5' ends (AAAC in the 5S rRNA). The sequence is also seen in the same position in several other plant mitochondrial mRNAs. We propose therefore that AAUC is a transcription or processing signal which is possibly unique to plant mitochondria.
通过直接RNA定位，我们确定了玉米线粒体26S rRNA精确的5'末端。26S rRNA的5'末端位于戴尔等人（1984年）根据玉米rRNA与大肠杆菌大亚基核糖体RNA之间的同源性预测的5'末端下游17和18个核苷酸处。此外，我们发现了一种更大的26S种类，可能是26S前体，并精确地定位了其5'末端。玉米线粒体rRNA基因可能受与其他基因组中已鉴定的调控区域不同的调控区域调控：玉米线粒体26S、18S和5S rRNA缺乏类似于其他线粒体和细菌基因启动子区域的序列。然而，成熟和前体rRNA在其5'末端均含有一个四核苷酸AAUC（5S rRNA中为AAAC）。该序列在其他几种植物线粒体mRNA的相同位置也可见。因此，我们提出AAUC是一种转录或加工信号，可能是植物线粒体所特有的。
