Kable M L, Seiwert S D, Heidmann S, Stuart K
Seattle Biomedical Research Institute, Seattle, WA 98109, USA.
Science. 1996 Aug 30;273(5279):1189-95. doi: 10.1126/science.273.5279.1189.
In the mitochondria of trypanosomatid protozoa the precursors of messenger RNAs (pre-mRNAs) have their coding information remodeled by the site-specific insertion and deletion of uridylate (U) residues. Small trans-acting guide RNAs (gRNAs) supply the genetic information for this RNA editing. An in vitro system was developed to study the mechanism of U insertion into pre-mRNA. U-insertion editing occurs through a series of enzymatic steps that begin with gRNA-directed pre-mRNA cleavage. Inserted U's are derived from free uridine triphosphate and are added to the 3' terminus of a 5' pre-mRNA cleavage product. gRNA specifies edited RNA sequence at the subsequent ligation step by base pairing-mediated juxtaposition of the 3' cleavage product and the processed 5' cleavage product. gRNA/pre-mRNA chimeras, purported intermediates, seem to be abortive end products of the same reaction.
在锥虫原生动物的线粒体中，信使核糖核酸（pre-mRNA）前体的编码信息通过尿苷酸（U）残基的位点特异性插入和缺失进行重塑。小的反式作用引导RNA（gRNA）为这种RNA编辑提供遗传信息。开发了一种体外系统来研究U插入pre-mRNA的机制。U插入编辑通过一系列酶促步骤发生，这些步骤始于gRNA引导的pre-mRNA切割。插入的U来源于游离的三磷酸尿苷，并添加到5' pre-mRNA切割产物的3'末端。gRNA在随后的连接步骤中通过碱基配对介导的3'切割产物与加工后的5'切割产物的并列来指定编辑后的RNA序列。gRNA/pre-mRNA嵌合体，据称是中间产物，似乎是同一反应的失败终产物。
