Table 3.
Active FNR concentrations and apparent dimerization rate constants (β22), as predicted by the model, for the FNR mutants constructed by Moore et al. (2006). Mutant strains contain amino acid substitutions in position 154, 152, 150, or 150/154. Experimental characterization of the mutants included an indirect assay for FNR activity using a narG-lacZ reporter construct under both aerobic and anaerobic conditions, and western blot analysis confirmed that FNR protein levels in these mutants are similar to wild-type. Activity was reported as the percentage of β-galactosidase activity in each mutant relative to the wild-type anaerobic β-galactosidase activity of FNR.
| FNR | % Activity (aerobic) |
% Activity (anaerobic) |
Active FNR (μM) |
Dimerization Rate Constant (β22 min−1 μM−2) |
|---|---|---|---|---|
| Wild-type | 4 | 100 | 0.072 ± 0.001 | 2.6 ± 0.63 |
| K152E | 4 ± 1 | 70 ± 7 | 0.0003 ± 0.0001 | 0.01 ± 0.004 |
| E150K-D154K | 6 ± 1 | 143 ± 14 | 0.1 ± 0.006 | 3.8 ± 0.3 |
| E150A | 15 ± 1 | 103 ± 10 | 0.26 ± 0.01 | 16 ± 2 |
| D154V | 15 ± 1 | 111 ± 11 | 0.27 ± 0.01 | 16 ± 2 |
| E150A-D154A | 16 ± 2 | 96 ± 10 | 0.28 ± 0.02 | 18 ± 2 |
| E150Q | 20 ± 2 | 100 ± 10 | 0.35 ± 0.02 | 27 ± 3 |
| E150K | 23 ± 2 | 112 ± 11 | 0.41 ± 0.02 | 39 ± 5 |
| D154G | 28 ± 3 | 116 ± 12 | 0.49 ± 0.03 | 64 ± 10 |
| D154C | 28 ± 3 | 115 ± 11 | 0.45 ± 0.03 | 65 ± 10 |
| D154L | 29 ± 3 | 103 ± 10 | 0.51 ± 0.03 | 72 ± 12 |
| D154N | 30 ± 3 | 140 ± 14 | 0.53 ± 0.03 | 80 ± 14 |
| D154A | 37 ± 4 | 102 ± 10 | 0.66 ± 0.04 | 181 ± 43 |
| E150K-D154A | 38 ± 4 | 115 ± 11 | 0.67 ± 0.04 | 206 ± 51 |
| D154K | 50 ± 5 | 109 ± 11 | 0.9 ± 0.04 | 2266 ± 1051 |