Covello P S, Gray M W
Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Nature. 1989 Oct 19;341(6243):662-6. doi: 10.1038/341662a0.
A basic principle of molecular biology is that the primary sequence of RNA faithfully reflects the primary sequence of the DNA from which it is transcribed. This concept has been challenged recently by the discovery of RNA editing, broadly defined as any process that changes the nucleotide sequence of an RNA molecule from that of the DNA template encoding it. Examples of RNA editing (see ref. 2 for review) include the insertion and deletion of uridine residues in mitochondrial messenger RNAs in kinetoplastid protozoa, the conversion of a cytidine to uridine in mammalian apolipoprotein-B mRNA, and the appearance of two non-templated guanosine residues in a paramyxovirus transcript. In these cases, RNA editing either re-tailors a non-functional transcript, producing a translatable mRNA, or modifies an already functional mRNA so that it generates a protein of altered amino-acid sequence. Here we report an editing phenomenon that involves the conversion of cytidine to uridine at multiple positions in the mRNA for subunit II of cytochrome c oxidase in wheat mitochondria. Such RNA editing provides an explanation for apparent coding anomalies in plant mitochondria.
分子生物学的一个基本原则是，RNA的一级序列忠实地反映了转录它的DNA的一级序列。最近，这一概念受到了RNA编辑发现的挑战，RNA编辑被广泛定义为任何改变RNA分子核苷酸序列使其不同于编码它的DNA模板序列的过程。RNA编辑的例子（综述见参考文献2）包括动质体原生动物线粒体信使RNA中尿苷残基的插入和缺失、哺乳动物载脂蛋白B mRNA中胞苷向尿苷的转变，以及副粘病毒转录本中两个非模板化鸟苷残基的出现。在这些情况下，RNA编辑要么重新改造一个无功能的转录本，产生一个可翻译的mRNA，要么修饰一个已经有功能的mRNA，使其产生一个氨基酸序列改变的蛋白质。在这里，我们报道了一种编辑现象，它涉及小麦线粒体细胞色素c氧化酶亚基II的mRNA中多个位置的胞苷向尿苷的转变。这种RNA编辑为植物线粒体中明显的编码异常提供了解释。
