The RNA moiety of ribonuclease P is the catalytic subunit of the enzyme.
The RNA moieties of ribonuclease P purified from both E. coli (M1 RNA) and B. subtilis (P-RNA) can cleave tRNA precursor molecules in buffers containing either 60 mM Mg2+ or 10 mM Mg2+ plus 1 mM spermidine. The RNA acts as a true catalyst under these conditions whereas the protein moieties of the enzymes alone show no catalytic activity. However, in buffers containing 5-10 mM Mg2+ (in the absence of spermidine) both kinds of subunits are required for enzymatic activity, as shown previously. In the presence of low concentrations of Mg2+, in vitro, the RNA and protein subunits from one species can complement subunits from the other species in reconstitution experiments. When the precursor to E. coli 4.5S RNA is used as a substrate, only the enzyme complexes formed with M1 RNA from E. coli and the protein moieties from either bacterial species are active.
D001412:Bacillus subtilis / Q000201:enzymology; D002384:Catalysis; D004722:Endoribonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D007700:Kinetics; D008274:Magnesium / Q000502:physiology; D012329:RNA, Bacterial / Q000502:physiology*; D043262:Ribonuclease P; D013045:Species Specificity; D013329:Structure-Activity Relationship
D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D004722:Endoribonucleases; D043262:Ribonuclease P; C470865:ribonuclease P, E coli; D008274:Magnesium