TABLE 2.
β-Galactosidase levels of lacZ fusions in wild-type and mutant strains grown in minimal medium
| lacZ fusiona | Relevant genotype | β-Galactosidase sp act (U/mg of protein) in cells grown onb:
|
Glucose repression ratioc | |
|---|---|---|---|---|
| Glucose | Citrate | |||
| HUT646 | Wild type | 0.9 | 11.6 | 13 |
| ptsH1 | 0.7 | 11.4 | 16 | |
| crh | 1.0 | 19.4 | 19 | |
| crh ptsH1 | 15.4 | 19.0 | 1.2 | |
| glcK | 1.2 | 12.0 | 10 | |
| HUT924 | Wild type | 2.2 | 28.8 | 13 |
| ptsH1 | 3.1 | 29.1 | 9.4 | |
| crh | 2.5 | 39.9 | 16 | |
| crh ptsH1 | 27.1 | 41.9 | 1.5 | |
| BGL2 | Wild type | 1.3 | 22.7 | 17 |
| ptsH1 | 4.2 | 20.7 | 4.9 | |
a
All strains were derivatives of strain 168 and had the indicated lacZ fusion integrated as a single copy at the amyE locus.
b
Data are the averages of three or more determinations, which did not vary by more than 15%. Cultures were grown in MOPS minimal medium containing glutamine as the nitrogen source and the indicated carbon source.
c
The glucose repression ratio was calculated by dividing the enzyme activity found in the culture grown with citrate by the enzyme activity found in the culture grown with glucose.