Table 1. RNase P protein activity and crosslink data.
| Protein | Percent wt activity (%) | Percent RNase P RNA crosslinked (%) | RNase P RNA site crosslinked | |
| |
Unmodified |
Azido |
|
|
| F18C/C113A | 30 | 60 | 2.9 | C228, U231 |
| H78C/C113A | 90 | 179 | 1.0 | C131, U167, C168, C228, U231, G246, C247 |
| R99C/C113A |
174 |
242 |
1.0 |
C228, U231 |
| C113 (wt) | 100 | 134 | 0.05 | n.d.a |
Activity measurements: initial velocity measurements of protein holoenzyme pre-tRNA cleavage activity for wild-type P protein (C113, wt) and mutants F18C/C113A, H78C/C113A and R99C/C113A are shown. Maximum percent cleaved was 26%. Percent crosslinking efficiencies: efficiencies were calculated from duplicate experiments using 20 nM each RNase P protein and RNA. Protein–RNA crosslinks were resolved on 4% acrylamide/8 M urea/ TBE gels similar to that in Figure 3. RNA site crosslinked: crosslink sites for F18C/C113A, H78C/C113A and R99C/C113A to RNase P RNA.
aThe crosslink site for C113 was not determined due to low efficiency of crosslinking.