TABLE 3.
Sensitivities of E. coli FhuA loop deletion mutants to antibiotics
| Strain or mutation | Deleted residues | Sensitivity toa:
|
|||
|---|---|---|---|---|---|
| Novobiocin (30 μg; 634 Da) | Erythromycin (15 μg; 734 Da) | Rifamycin (5 μg; 823 Da) | Bacitracin (30 μg; 1,421 Da) | ||
| Vector | no FhuA | 10 | 7 | − | − |
| Wild type | 10 | 7 | − | − | |
| ΔLoop 3 | 243-273 | 14 | 11 | 14 | − |
| ΔLoop 4 | 318-339 | 12 | 8 | 7 | − |
| ΔLoop 5 | 394-419 | 12 | 8 | 10 | − |
| ΔLoop 7 | 502-515 | 12 | 8 | 10 | − |
| ΔLoop 8 | 552-558 | 11 | 7 | 6 | − |
| ΔLoop 9 | 598-611 | 12 | 11 | 8 | − |
| ΔLoop 10 | 640-654 | 12 | 9 | 9 | − |
| ΔLoop 11 | 689-701 | 15 | 11 | 13 | 8 |
a
Sensitivities to the ligands were tested using E. coli MB98 ΔfhuA freshly transformed with the plasmids listed in Table 1 expressing the indicated FhuA derivatives cloned into pT7-6. Sensitivities were tested by placing filter disks containing the various inhibitors onto TY agar plates overlaid with TY soft agar containing the strain to be tested. The size of the inhibition zone (in millimeters) is given without subtraction of the size of the paper disk (6 mm) used to supply the inhibitors at the concentration given. The molecular masses of the inhibitors are indicated. Numbers in parentheses indicate turbid zones of growth inhibition. −, no sensitivity.