Table 2.
K d values for repressor‐DNA bindinga
| Assay | Filter binding | BLI | Fold‐change | ||||
|---|---|---|---|---|---|---|---|
| Repressor | DNA | Avg (M) | Error | Avg (M) | Error | Avg (M) | Error |
| LacI | lacO 1 | 4.5 × 10−11 | 2.8 × 10−11 | n.d | — | — | — |
| lacO 2 | 5.2 × 10−10 | 0.3 × 10−10 | 2.7 × 10‐11 b | 1.6 × 10−11 | 0.05 | 0.14 | |
| lacO 3 | ≥10−7 | — | 0.5 × 10−7 | 0.2 × 10−7 | — | — | |
| LLhF | lacO 1 | 0.4 × 10−8 | 0.1x10−8 | 1.8x10−8 | 0.3 × 10−8 | 4.80 | 0.54 |
| lacO 2 | 4.1 × 10−8 | 3.2 × 10−8 | 4.8 × 10−8 | 1.9 × 10−8 | 1.15 | 0.94 | |
| lacO 3 | ≥10−6 | — | ≥10−5 | — | — | — | |
Abbreviations: BLI, biolayer interferometry; n.d., not determined.
All values are reported in M dimeric repressor. Average (Avg) values were determined using at least three independent determinations comprising at least two independent protein purifications. Reported errors represent one standard deviation of the mean. Fold‐change values were determined by dividing the BLI value by the filter binding value, and errors were propagated from the experimental data. All filter binding assays used a fixed DNA concentration of ~3 × 10−12 M DNA; all BLI assays used 80 nM of the indicated DNA for the immobilization step.
Estimated from simultaneous fits of replicate assays in the intermediate binding regime (Figure S7); the error shown is the standard error of the fit; as described in the text, the 95% lower confidence limit was unbounded, the upper limit was 7.2 × 10−11 M.