Harris M, Decker C, Sollner-Webb B, Hajduk S
Department of Biochemistry, School of Medicine, University of Alabama, Birmingham 35294.
Mol Cell Biol. 1992 Jun;12(6):2591-8. doi: 10.1128/mcb.12.6.2591-2598.1992.
RNA editing in Trypanosoma brucei is a posttranscriptional processing event that results in the addition and deletion of uridine residues within several mitochondrial mRNAs. We have examined reactions involving pre-edited precursor RNAs in vitro. In this study, we report specific cleavage of pre-edited cytochrome b (CYb), cytochrome oxidase subunit II (COII), and cytochrome oxidase subunit III (COIII) mRNAs when incubated with T. brucei mitochondrial extracts. The pre-edited CYb RNA was cleaved near the 3'-most uridine addition sites, within the region where editing would be expected to commence. Pre-edited COII mRNA was similarly cleaved adjacent to its small editing domain, while pre-edited COIII RNA was cleaved at multiple sites in the region where uridine addition and deletion occurs in vivo. In contrast, edited versions of CYb, COII, and COIII RNAs were not cleaved within the editing domains. Such differential cleavage of the edited and pre-edited forms of these mRNAs suggests either a direct involvement in RNA editing or involvement in another aspect of mitochondrial gene expression requiring cleavage of pre-edited RNAs.
布氏锥虫中的RNA编辑是一种转录后加工事件，会导致几种线粒体mRNA中尿苷残基的添加和缺失。我们已经在体外研究了涉及预编辑前体RNA的反应。在本研究中，我们报告了预编辑的细胞色素b（CYb）、细胞色素氧化酶亚基II（COII）和细胞色素氧化酶亚基III（COIII）mRNA与布氏锥虫线粒体提取物一起孵育时会发生特异性切割。预编辑的CYb RNA在最靠近3'端的尿苷添加位点附近、预期编辑开始的区域内被切割。预编辑的COII mRNA在其小编辑结构域附近同样被切割，而预编辑的COIII RNA在体内发生尿苷添加和缺失的区域的多个位点被切割。相比之下，CYb、COII和COIII RNA的编辑版本在编辑结构域内未被切割。这些mRNA的编辑形式和预编辑形式的这种差异切割表明，要么直接参与RNA编辑，要么参与线粒体基因表达的另一个需要切割预编辑RNA的方面。
