Ion dependence of the Bacillus subtilis RNase P reaction.
The properties of the Bacillus subtilis RNase P are characterized with regard to the types and concentrations of monovalent and divalent ions required to potentiate precursor tRNA cleavage by the protein-RNA holoenzyme and the catalytic RNA alone. The ionic dependence of the RNase P RNA-catalyzed reaction in part seems due to a requirement for ion shielding between substrate and catalytic RNAs. The RNase P protein, which binds to RNA nonspecifically and tightly, likely serves, in part, as a cation screen. However, the character of the ion dependence of the RNA catalysis, the inhibition by high SO2-4 concentration, and potentiation by solvents suggest that RNA conformational transition may be involved in the reaction. It is proposed that the reason for catalysis by RNA in the RNase P reaction may be a requirement for fluidity in the structure of the catalyst, so that it can accommodate many tRNA substrates, which vary in their structural details.
D001412:Bacillus subtilis / Q000201:enzymology*; D002412:Cations / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D043262:Ribonuclease P; D013431:Sulfates / Q000494:pharmacology
D002412:Cations; D013431:Sulfates; D000431:Ethanol; D008345:Manganese; D004722:Endoribonucleases; D043262:Ribonuclease P; D008274:Magnesium