E. coli RNAase P has a required RNA component in vivo

RNAase P has been partially purified from three thermosensitive strains of E. coli and the thermal inactivation characteristics of each preparation have been determined. The RNAase P preparations from two of these mutant strains, ts241 and ts709, and the wild-type strain have been separated into RNA and protein components. Various mixtures of the reconstituted components have been checked in vitro for complementation of their thermal sensitivity properties. The protein component of RNAase P from ts241 and the RNA component of RNAase P from ts709, respectively, account for the thermal sensitivity of the RNAase P from the two strains. The amount of the RNA component of RNAase P is lower in ts709 than in ts241 or the wild-type parent, 4273. RNAase P partially purified from a revertant of the third mutant strain, A49, which maps at or near the ts241 mutation, has an altered charge when compared to the RNAase P from the parent strain, BF265. We conclude that mutations which affect either the protein or RNA component of RNAase P can confer thermal sensitivity on the enzyme both in vivo and in vitro.