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Eukaryotic RNase P RNA mediates cleavage in the absence of protein
- Kikovska, Ema, Svärd, Staffan G., Kirsebom, Leif A.
- Proceedings of the National Academy of Sciences of the United States of America 2007 v.104 no.7 pp. 2062-2067
- Giardia lamblia, RNA precursors, catalytic activity, eukaryotic cells, evolution, humans, protein subunits, ribonucleases, ribonucleoproteins, transfer RNA
- The universally conserved ribonucleoprotein RNase P is involved in the processing of tRNA precursor transcripts. RNase P consists of one RNA and, depending on its origin, a variable number of protein subunits. Catalytic activity of the RNA moiety so far has been demonstrated only for bacterial and some archaeal RNase P RNAs but not for their eukaryotic counterparts. Here, we show that RNase P RNAs from humans and the lower eukaryote Giardia lamblia mediate cleavage of four tRNA precursors and a model RNA hairpin loop substrate in the absence of protein. Compared with bacterial RNase P RNA, the rate of cleavage (kobs) was five to six orders of magnitude lower, whereas the affinity for the substrate (appKd) was reduced [almost equal to]20- to 50-fold. We conclude that the RNA-based catalytic activity of RNase P has been preserved during evolution. This finding opens previously undescribed ways to study the role of the different proteins subunits of eukaryotic RNase P.