TABLE 2.
Strain
|
Activator controlled by lac promoter | No treatment with 2,2′-dipyridyl
|
Treatment with 5 mM 2,2′-dipyridyl
|
|||||
---|---|---|---|---|---|---|---|---|
β-Galactosidase activity (MU)
|
Ratiob | β-Galactosidase activity (MU)
|
Ratiob | |||||
tolC+ | tolC | tolC+ strain | tolC strain | tolC+ strain | tolC strain | |||
M4110 | M4114 | None | 6.1 (0.42)c | 11 (1.6) | 1.8 | 12 (0.6) | 16 (1.8) | 1.3 |
M4111 | M4115 | MarA | 85 (15) | 84 (17) | 1.0 | 63 (17) | 53 (7.4) | 0.84 |
M4112 | M4116 | SoxS | 80 (24) | 81 (20) | 1.0 | 72 (18) | 61 (9.2) | 0.85 |
M4113 | M4117 | Rob | 42 (10) | 209 (58) | 5.0 | 675 (139) | 919 (154) | 1.4 |
Strains were grown in LB broth at 32°C to an A600 of 0.1, diluted twofold into LB broth with or without 2,2′-dipyridyl, and aerated for 1 h at 32°C. Cells were placed on ice, and an assay was performed to determine the β-galactosidase activity, which was expressed in Miller units (MU). All strains have chromosomal lacIZYA, marRAB, soxS, and rob null mutations.
Ratio of the activity in the tolC mutant to the activity in the tolC+ strain.
The standard errors of the means are indicated in parentheses.