Characterization of RNA-based and protein-only RNases P from bacteria encoding both enzyme types

Pre-tRNA processing activity of P RNAs from E. coli (Eco), A. ehrlichii (Aehr), H. halophila (Hhal), M. infernorum (Minf), T. indicus (Tind), and T. nitratireducens (Tnit) under single turnover conditions. (A) RNA-alone reaction containing 25 nM P RNA and <1 nM of 5′-³²P-endlabeled pre-tRNA^Gly were conducted at 25°C in the presence of 100 mM Mg²⁺. (B) For the holoenzyme reaction, 50 nM B. subtilis P protein was added to 10 nM P RNA, and substrate (<1 nM of 5′-³²P-endlabeled pre-tRNA^Gly) processing was analyzed in the presence of 4.5 mM Mg²⁺ at 25°C. The rate constants k_obs (min⁻¹) obtained under these conditions are given for each P RNA in the RNA-alone or holoenzyme reaction, based on three or more independent experiments for each enzyme. Error bars are standard deviations (SD). For more details, see Materials and Methods.