TABLE 1.
Regulation of trp leader transcription in vivo
| TRAP | Trpa | β-Galactosidase activity (U)b | Fold regulationc |
|---|---|---|---|
| No pHYp59mtrB | − | 312 ± 56 | |
| + | 286 ± 33 | 1.1 | |
| WT | + | 7 ± 1 | 45 |
| E60K mutant | + | 23 ± 2 | 14 |
| E60R mutant | + | 19 ± 1 | 16 |
| E60D mutant | + | 7 ± 1 | 45 |
a
−, absence of exogenous l-tryptophan; +, presence of 50 μg/ml l-tryptophan.
b
Values are the averages ± standard deviations for two or three independent experiments, each performed in triplicate.
c
Fold regulation of TRAP in response to tryptophan-activated TRAP, calculated by dividing the value for no pHYp59mtrB plasmid with no added Trp (312 U) by each value for TRAP with added Trp.