Jiang Taijiao, Altman Sidney
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5295-300. doi: 10.1073/pnas.072083699. Epub 2002 Apr 2.
The processing of precursor tRNAs at their 5' and 3' termini is a fundamental event in the biosynthesis of tRNA. RNase P is generally responsible for endonucleolytic removal of a leader sequence of precursor tRNA to generate the mature 5' terminus. However, much less is known about the RNase P counterparts or other proteins that are active at the tRNA 3' terminus. Here we show that one of the human RNase P subunits, Rpp14, together with one of its interacting protein partners, OIP2, is a 3'-->5' exoribonuclease with a phosphorolytic activity that processes the 3' terminus of precursor tRNA. Immunoprecipitates of a crude human RNase P complex can process both ends of precursor tRNA by hydrolysis, but purified RNase P has no exonuclease activity. Rpp14 and OIP2 may be part of an exosome activity.
前体tRNA在其5'和3'末端的加工是tRNA生物合成中的一个基本事件。核糖核酸酶P通常负责内切去除前体tRNA的前导序列以产生成熟的5'末端。然而，对于在tRNA 3'末端起作用的核糖核酸酶P对应物或其他蛋白质，我们了解得要少得多。在这里，我们表明人类核糖核酸酶P亚基之一Rpp14与其相互作用的蛋白质伙伴之一OIP2是一种具有磷酸解活性的3'→5'外切核糖核酸酶，可加工前体tRNA的3'末端。粗制的人类核糖核酸酶P复合物的免疫沉淀物可通过水解加工前体tRNA的两端，但纯化的核糖核酸酶P没有外切核酸酶活性。Rpp14和OIP2可能是外切体活性的一部分。
