TABLE 4.
Effect of mutations in possible GntR-binding sequences on the expression of a multicopy gntK-lacZ fusion in LB medium
| Gnt-lacZ fusion plasmid in YU577 | β-Galactosidase activity (Miller units)a
|
|||||
|---|---|---|---|---|---|---|
| No addition
|
GAb addition
|
|||||
| pYY2c | pGNTR1c | pGNTHc | pYY2 | pGNTR1 | pGNTH | |
| pGNTK-LAC | 480 ± 84 | 42 ± 4.8 | 260 ± 29 | 450 ± 166 | 120 ± 23 | 220 ± 1.4 |
| pGNTK-LACMR1 | 530 ± 72 | 280 ± 47 | 510 ± 9.9 | 470 ± 48 | 480 ± 55 | 530 ± 45 |
| pGNTK-LACMR2 | 390 ± 14 | 41 ± 2.7 | 240 ± 36 | 470 ± 1.5 | 260 ± 35 | 220 ± 20 |
| pGNTK-LACMR12 | 530 ± 28 | 300 ± 2.3 | 390 ± 15 | 410 ± 12 | 490 ± 53 | 430 ± 41 |
a
Cells were incubated at 37°C for 4 h, and β-galactosidase activity was measured as described in Materials and Methods. Reported values are means and standard deviations of more than two independent experiments performed in triplicate.
b
0.5% gluconate (GA) was added after a 2-h incubation.
c
pYY2 as the control plasmid, pGNTR1 bearing gntR, or pGNTH bearing gntH was cointroduced into YU577.