Morales M J, Wise C A, Hollingsworth M J, Martin N C
Department of Biochemistry, University of Louisville School of Medicine, KY 40292.
Nucleic Acids Res. 1989 Sep 12;17(17):6865-81. doi: 10.1093/nar/17.17.6865.
We have previously described a mitochondrial activity that removes 5' leaders from yeast mitochondrial precursor tRNAs and suggested that it is a mitochondrial RNase P. Here we demonstrate that the cleavage reaction results in a 5' phosphate on the tRNA product and thus the activity is analogous to that of other RNase Ps. A mitochondrial gene called the tRNA synthesis locus encodes an A + U-rich RNA required for this activity in vivo. Two regions of this RNA display sequence similarity to conserved sequences in bacterial RNase P RNAs. This sequence similarity coupled with the analogous activities of the enzymes has led us to conclude that the RNAs are homologous and that the tRNA synthesis locus does code for the mitochondrial RNase P RNA subunit. The smallest and most abundant transcript of the tRNA synthesis locus is 490 nucleotides long. However, during purification of the holoenzyme, RNA is degraded and pieces of the original RNA are sufficient to support RNase P activity in vitro.
我们之前描述过一种线粒体活性，它能从酵母线粒体前体tRNA上去除5'端前导序列，并认为它是一种线粒体核糖核酸酶P。在此我们证明，切割反应会使tRNA产物产生一个5'磷酸基团，因此该活性与其他核糖核酸酶P的活性类似。一个名为tRNA合成位点的线粒体基因编码一种富含A + U的RNA，该RNA在体内是此活性所必需的。这种RNA的两个区域与细菌核糖核酸酶P RNA中的保守序列具有序列相似性。这种序列相似性以及酶的类似活性使我们得出结论，这些RNA是同源的，并且tRNA合成位点确实编码线粒体核糖核酸酶P RNA亚基。tRNA合成位点最小且最丰富的转录本长度为490个核苷酸。然而，在全酶纯化过程中，RNA会被降解，原始RNA的片段就足以在体外支持核糖核酸酶P的活性。
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