Hunt M D, Newton K J
Department of Biological Sciences, University of Missouri, Columbia 65211.
EMBO J. 1991 May;10(5):1045-52. doi: 10.1002/j.1460-2075.1991.tb08043.x.
A deletion eliminating part of a transcribed region of mitochondrial DNA (mtDNA) has been found in the maize nonchromosomal stripe 3 (NCS3) mutant. This results in the specific loss of a set of three mitochondrial RNAs consisting, in normal plants, of a 4.9 kb transcript, its 1.8 kb intron and the resulting processed mRNA of approximately 2.9 kb. In the NCS3 mitochondrial genome the DNA encoding the putative promoter and 5' end of the affected RNAs is missing. This transcribed region of normal maize mtDNA has been sequenced and the intron splice junction has been determined. The 2.9 kb processed mRNA carries two overlapping open reading frames (ORFs) with predicted amino acid sequences that show similarity to two Escherichia coli ribosomal proteins, S3 (rps3) and L16 (rpl16). The presence of severe stunting and striping in NCS3 plants correlates absolutely with the molecular changes described here. This fact and the impaired ability for mitochondrial protein synthesis by NCS3 plants indicate that one or both of these reading frames are translated to functional ribosomal proteins in normal maize mitochondria.
在玉米非染色体条纹3（NCS3）突变体中发现了一个缺失，该缺失消除了线粒体DNA（mtDNA）转录区域的一部分。这导致一组三条线粒体RNA特异性缺失，在正常植物中，这组RNA由一个4.9 kb的转录本、其1.8 kb的内含子以及产生的约2.9 kb的加工mRNA组成。在NCS3线粒体基因组中，编码受影响RNA的假定启动子和5'端的DNA缺失。已对正常玉米mtDNA的该转录区域进行了测序，并确定了内含子剪接位点。2.9 kb的加工mRNA携带两个重叠的开放阅读框（ORF），其预测的氨基酸序列与两种大肠杆菌核糖体蛋白S3（rps3）和L16（rpl16）相似。NCS3植物中严重的发育迟缓和平行条纹与这里描述的分子变化完全相关。这一事实以及NCS3植物线粒体蛋白质合成能力受损表明，在正常玉米线粒体中，这些阅读框中的一个或两个被翻译成功能性核糖体蛋白。
