Table 1.
Calculated kinetic parameters for wild type SecA in the context of various translocation partners
| Mg2+ | SecYEG (soluble in 0.1% C12E9) | SecYEG (proteoliposomes) | proOmpA | Kd,app[SecA·ligand], μM |
|---|---|---|---|---|
| + | Ligand titrated | − | − | 3.88 ± 0.31 |
| + | − | Ligand titrated | − | 0.52 ± 0.11* |
| + | − | +1 μM | Ligand titrated | 0.047 ± 0.017 |
The steady-state ATPase activity of purified wild type SecA was measured with increasing concentrations of translocation ligand, and fitted according to a 1-site ligand binding equation (Eqs. 1 or 3 in SI Equations) to determine values for Kd,app.
*, the Kd,app for SecA binding to SecYEG proteoliposomes is 0.26 μM assuming a 50% right-side out reconstitution.