TABLE 2.
Histidine-induced expression of the hutU-G operon in different genetic backgrounds
| Fusion strain | Genetic background | β-Galactosidase activitya
|
||
|---|---|---|---|---|
| Ammonium | Histidine | Histidine + Gln | ||
| PBR813 | Wild type | 1.04 ± 0.13 (a) | 25.67 ± 5.84 (c) | 20.71 ± 1.64 (c) |
| PBR833 | ΔntrC | 0.90 ± 0.18 (a) | 22.20 ± 1.15 (c) | |
| PBR834 | ΔcbrB | 0.63 ± 0.08 (a) | 8.29 ± 3.72 (b) | |
| PBR835 | ΔntrC ΔcbrB | 0.76 ± 0.37 (a) | 0.68 ± 0.18 (a) | 0.96 ± 0.26 (a) |
| PBR836 | Δpflu4026 | 1.20 ± 0.14 (a) | 23.23 ± 2.83 (c) | |
| PBR837 | ΔrpoN | 0.43 ± 0.13 (a) | 0.25 ± 0.02 (a) | 0.26 ± 0.01 (a) |
a
β-Galactosidase activities (amol 4MU min−1 cell−1) were measured for cells growing in MSM supplemented with glucose (as C) and different N source: ammonium, histidine (15 mm), or histidine (15 mm) and glutamine (Gln, 1 mm). Data are means and standard errors of three independent cultures. Two-way ANOVA revealed a highly significant difference among means [F5,23 = 13.02, P < 0.0001]. Activities identified by different letters in parentheses are significantly different (P < 0.05) by Tukey's HSD test.