TABLE 2.
Responses of czc promoters to heavy metals
| CBA system | Inducer | Growth |
Development |
||||
|---|---|---|---|---|---|---|---|
| Metal concn (mM) | Avg β-galactosidase activity ± SDb | Fold inductiona | Metal concn (mM) | Avg β-galactosidase activity ± SDb | Fold inductiona | ||
| czc1 | None | 1 ± 0.1 | 0.7 ± 0.1 | ||||
| CuSO4 | 0.3 | ND | 0.060 | ND | |||
| Ni(NO3)2 | 1.0 | 483 ± 48 | 483 | 2.0 | ND | ||
| Zn(NO3)2 | 0.25 | ND | 0.1 | ND | |||
| Co(NO3)2 | 0.5 | 618 ± 42 | 618 | 1.0 | 624 ± 37 | 891 | |
| Cd(NO3)2 | 0.1 | 133 ± 3 | 133 | 0.025 | 221 ± 5 | 316 | |
| FeSO4 | 4.0 | 576 ± 36 | 576 | 6.0 | 38 ± 0.4 | 54 | |
| MnSO4 | 0.6 | 458 ± 43 | 458 | 0.8 | 565 ± 19 | 807 | |
| AgNO3 | 0.1 | ND | 0.01 | ND | |||
| AuCl3 | 1.0 | ND | 0.25 | ND | |||
| czc2 | None | 4 ± 0.3 | 18 ± 0.3c | ||||
| CuSO4 | 0.3 | 46 ± 4 | 12 | 0.060 | 20 ± 1 | 1 | |
| Ni(NO3)2 | 1.0 | ND | 2.0 | ND | |||
| Zn(NO3)2 | 0.25 | 19 ± 1 | 5 | 0.1 | ND | ||
| Co(NO3)2 | 0.5 | ND | 1.0 | ND | |||
| Cd(NO3)2 | 0.1 | 27 ± 0.4 | 7 | 0.025 | 55 ± 2 | 3 | |
| FeSO4 | 6.0 | ND | 6.0 | ND | |||
| MnSO4 | 0.6 | ND | 0.8 | ND | |||
| AgNO3 | 0.1 | ND | 0.01 | ND | |||
| AuCl3 | 1.0 | ND | 0.25 | ND | |||
| czc3 | None | 27 ± 1 | 642 ± 9 | ||||
| CuSO4 | 0.3 | 21 ± 1 | 1 | 0.060 | 56 ± 3 | 0.1 | |
| Ni(NO3)2 | 1.0 | 5 ± 1 | 0.2 | 2.0 | 97 ± 1 | 0.2 | |
| Zn(NO3)2 | 0.25 | 9 ± 1 | 0.3 | 0.1 | 48 ± 0.1 | 0.1 | |
| Co(NO3)2 | 0.5 | 5 ± 1 | 0.2 | 1.0 | 36 ± 1 | 0.1 | |
| Cd(NO3)2 | 0.1 | 12 ± 1 | 0.4 | 0.025 | 74 ± 5 | 0.1 | |
| FeSO4 | 6.0 | 11 ± 1 | 0.4 | 6.0 | 70.1 ± 0.3 | 0.1 | |
| MnSO4 | 0.6 | 5 ± 1 | 0.2 | 0.8 | 138 ± 6 | 0.2 | |
| AgNO3 | 0.1 | 8 ± 3 | 0.3 | 0.01 | 56 ± 1 | 0.1 | |
| AuCl3 | 1.0 | 11 ± 0.5 | 0.4 | 0.25 | 127 ± 2 | 0.2 | |
a
Fold induction was calculated by dividing the means of the respective β-galactosidase activities by the average values for the uninduced cells (none).
b
ND, not detectable. β-Galactosidase activity was not quantified when blue color was not detected during the qualitative assay.
c
The maximum level of expression of czc2 in the absence of copper is reached at 8 h. The presence of copper delayed the maximum up to 24 h (Fig. 4). For comparison, we used samples obtained at 8 h as controls for the assay in the absence of copper and at 24 h when copper was added.