The RNR motif of B. subtilis RNase P protein interacts with both PRNA and pre-tRNA to stabilize an active conformer

Mutations in P protein affect RNase P-catalyzed cleavage of pre-tRNA in magnesium. (A) Time courses for single turnover cleavage of pre-tRNA^Asp catalyzed by R60A RNase P at pH 6.0 (circles, dashed line) and pH 8.0 (diamonds, solid line) in 10 mM MgCl₂ and buffer. (B) pH dependence of single turnover rate constants catalyzed by wild-type (squares, solid line), R60A (triangles, dotted line), and R62A (circles, dashed line) RNase P in 10 mM MgCl₂ (pH 5–8) and buffer. The values of the pH-independent single turnover rate constant and observed pK_a, determined from a fit of a single ionization to these data, are listed in Table 2.