Price D H, Gray M W
Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada.
Curr Genet. 1999 Feb;35(1):23-9. doi: 10.1007/s002940050428.
In the amoeboid protozoon Acanthamoeba castellanii 13 of the 16 mtDNA-encoded tRNA sequences have mis-matches at one or more of the first three positions in the acceptor stem. A previous study had indicated that these mis-matches are corrected by a form of RNA editing. In the present study, the pattern of editing was further investigated by sequence analysis of both halves of the acceptor stem of 11 mtDNA-encoded tRNAs. The results confirm all of the remaining editing sites predicted on the basis of the secondary structure modelling of A. castellanii mitochondrial tRNAs, and identify two unexpected edits. We also investigated the expression and editing of transcripts of an unusual trnX gene specifying an eight-nucleotide anticodon loop sequence. Although no mature 3'-CCAOH-containing tRNAX products were detected, editing was observed in some circularized tRNAX clones. The implications of these results with respect to the mechanism of editing and the evolutionary origin of this process are discussed.
在变形虫类原生动物卡氏棘阿米巴中，16个线粒体DNA编码的tRNA序列中有13个在受体茎的前三个位置中的一个或多个位置存在错配。先前的一项研究表明，这些错配通过一种RNA编辑形式得到校正。在本研究中，通过对11个线粒体DNA编码的tRNA受体茎的两半进行序列分析，进一步研究了编辑模式。结果证实了基于卡氏棘阿米巴线粒体tRNA二级结构模型预测的所有剩余编辑位点，并确定了两个意外的编辑。我们还研究了一个不寻常的trnX基因转录本的表达和编辑，该基因指定了一个八核苷酸反密码子环序列。尽管未检测到成熟的含3'-CCAOH的tRNAX产物，但在一些环化的tRNAX克隆中观察到了编辑。讨论了这些结果对编辑机制和该过程进化起源的影响。
