TABLE 2.
Effect of nmrA deletions on nitrogen metabolite repression of nitrate reductase expression
| Nitrogen sourcea | Nitrate reductase level (mU/min/mg of protein)b
|
|||
|---|---|---|---|---|
| nmrA | % Dere- pressionc | ΔnmrA::argB | % Dere- pressionc | |
| NO3 | 66.5 ± 16.1 | 63.6 ± 11.2 | ||
| NO3 + NH4 | 6.2 ± 2.8 | 9 | 27.5 ± 6.3 | 43 |
| NO3 + Gln | 4.7 ± 0.5 | 7 | 28.7 ± 4.6 | 45 |
a
Mycelium was grown for 16 h at 37°C in glucose minimal medium (9) containing in each case the following nitrogen sources: 10 mM ammonium tartrate (NH4) and sodium nitrate (NO3).
b
Nitrate reductase levels were assayed by the method of Cove (9) and are expressed as means ± standard errors.
c
The percentage of derepression is calculated as the level of enzyme activity under repressed conditions relative to that under nonrepressed conditions: NO3 plus NH4 and NO3 plus Gln relative to NO3.