Liu M H, Yuan Y, Reddy R
Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030.
Mol Cell Biochem. 1994 Jan 12;130(1):75-82. doi: 10.1007/BF01084270.
RNase P in both prokaryotes and eukaryotes is a ribonucleoprotein that cleaves tRNA precursors to generate the 5' termini of the mature tRNAs. Many patients with autoimmune diseases produce antibodies against a 40 kDa protein (designated To or Th antigen) which is an integral component of eukaryotic RNaseP as well as nucleolar 7-2 RNP which is identical to the mitochondrial RNA processing (MRP) RNP. Interestingly, the To antigen found in human cells and the C5 protein, the only protein component of E. coli RNaseP, are antigenically related. In this study, we show that a 56 nucleotide-long sequence, corresponding to nucleotides 20-75 near the 5' end of human RNaseP RNA, is sufficient to bind the To antigen. We previously showed that the human To antigen binds to a short distinct structural domain near the 5' end of human 7-2/MRP RNA. There is no obvious primary sequence homology between the To antigen binding sites in RNaseP RNA and 7-2/MRP RNA; however, these sequences are capable of assuming a similar secondary structure which corresponds to the recently proposed 'cage' structure for RNaseP RNAs and 7-2/MRP RNA (Forster and Altman (1989) Cell 62: 407-409). These data are supportive of the idea that these two RNAs may have evolved from a common progenitor molecule.
原核生物和真核生物中的核糖核酸酶P都是一种核糖核蛋白，它能切割tRNA前体以产生成熟tRNA的5'末端。许多自身免疫性疾病患者会产生针对一种40 kDa蛋白（称为To或Th抗原）的抗体，该蛋白是真核核糖核酸酶P以及核仁7 - 2 RNP的一个组成部分，而核仁7 - 2 RNP与线粒体RNA加工（MRP）RNP相同。有趣的是，在人类细胞中发现的To抗原与大肠杆菌核糖核酸酶P的唯一蛋白质成分C5蛋白在抗原性上相关。在本研究中，我们表明一段56个核苷酸长的序列，对应于人类核糖核酸酶P RNA 5'端附近的核苷酸20 - 75，足以结合To抗原。我们之前表明人类To抗原与人类7 - 2/MRP RNA 5'端附近一个短的独特结构域结合。核糖核酸酶P RNA和7 - 2/MRP RNA中的To抗原结合位点之间没有明显的一级序列同源性；然而，这些序列能够呈现出相似的二级结构，这与最近提出的核糖核酸酶P RNA和7 - 2/MRP RNA的“笼状”结构相对应（福斯特和阿尔特曼（1989年）《细胞》62卷：407 - 409页）。这些数据支持了这两种RNA可能从一个共同的祖先进化而来的观点。
