TABLE 1.
Nucleotide binding affinities of WT MsbA are maintained in the MsbA mutants
| MsbA protein | TNP-ATP binding, KdTNP-ATP (μm)a | TNP-ATP displacement |
|||
|---|---|---|---|---|---|
| by ADP |
by ATP |
||||
| IC50 (mm)b | KdADP (mm)b | IC50 (μm)b | KdATP (μm)b | ||
| WT | 0.6 ± 0.1 | 43.9 ± 11.5 | 2.2 ± 0.7 | 261 ± 40 | 13.1 ± 3.0 |
| E208A | 0.8 ± 0.1 | 43.7 ± 12.9 | 2.9 ± 0.9 | 197 ± 40 | 12.9 ± 3.2 |
| K212A | 1.2 ± 0.1 | 66.3 ± 26.1 | 6.3 ± 3.6 | –c | – |
| A281C | 0.6 ± 0.0 | 29.9 ± 9.4 | 1.5 ± 0.5 | – | – |
| E208A/A281C | 0.6 ± 0.1 | 48.3 ± 7.7 | 2.4 ± 0.6 | – | – |
a KdTNP-ATP values were obtained from the main data in Fig. 5 by nonlinear regression analysis with Equation 1 under “Binding Assays.”
b IC50 values were obtained from the data in Fig. 5, inset, by nonlinear regression analysis with Equation 2 under “Binding Assays” and were used for calculation of KdADP and KdATP in Equation 3.
c – means not determined.