Eukaryotic RNase P RNA mediates cleavage in the absence of protein.
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 (k(obs)) was five to six orders of magnitude lower, whereas the affinity for the substrate (appK(d)) was reduced approximately 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.
Kikovska
Ema
E
Department of Cell and Molecular Biology, Uppsala University, Box 596, Biomedical Centre, SE-751 24 Uppsala, Sweden.
Svärd
Staffan G
SG
Kirsebom
Leif A
LA
D000818:Animals; D002384:Catalysis; D017124:Conserved Sequence; D005057:Eukaryotic Cells; D019143:Evolution, Molecular; D016829:Giardia lamblia; D006801:Humans; D007700:Kinetics; D009690:Nucleic Acid Conformation; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism; D012343:RNA, Transfer; D043262:Ribonuclease P / Q000235:genetics* / Q000378:metabolism*
D015800:Protozoan Proteins; D012322:RNA Precursors; D012313:RNA; D012343:RNA, Transfer; D043262:Ribonuclease P