TABLE 5.
In vivo termination activity in nutL-ΔrIII mutanta
| Strain | Presence of sequence
|
Addition of arabinose | β-Galactosidase activity (Miller units) | % Readthrough | |
|---|---|---|---|---|---|
| rIII | nun | ||||
| N9478 | + | − | − | 2,000 ± 440 | 100 |
| N9482 | + | + | − | 60 ± 30 | 3.0 |
| N9482 | + | + | + | 12 ± 0.6 | 0.6 |
| N9479 | − | − | − | 2,000 ± 220 | 100 |
| N9483 | − | + | − | 130 ± 24 | 6.5 |
| N9483 | − | + | + | 26 ± 5 | 1.3 |
a
All strains carry either pL-nutL-rIII-N-lacZ (rIII+) or pL-nutL-ΔrIII-N-lacZ (rIII mutant) under the control of the λ cI857 ts repressor. Nun was expressed from plasmid pBAD-NunK107A. Arabinose was added to 0.05%, where indicated, to induce Nun. Strains were grown at 32°C to mid-log phase, shifted to 42°C for 1.5 h to induce pL, and assayed for β-galactosidase activity. Values are given in Miller units and represent the averages ± standard deviations for three or more experiments.