Table 2.
Properties of wild-type and β′::σ70 fusion strains in various conditions
| Phenotype | Required factor | Wild-type σ70 levela | β′::σ70, no add. σ70a | β′::σ70, plus σ70a |
|---|---|---|---|---|
| λ growthb | NusA, B, E, G | 1 | 0.8 ± 0.2 | 1.0 ± 0.4 |
| Growth at 45°Cc | σ32, σE | 1.0 ± 0.2 | 1.0 ± 0.1 | 1.0 ± 0.1 |
| Growth on Arg/Glnd | σN | 1.2 ± 0.3 | 1.3 ± 0.1 | 1.0 ± 0.4 |
| Motilitye | σF | 1 | 1.0 ± 0.1 | 1.0 ± 0.1 |
| Catalase productionf | σS | + | + | + |
The strains for the wild-type σ70 level were RL301 or C600 K-. The β′::σ70, no additional σ70 strain was RL1094 (chromosomally encoded σ70 not expressed). The β′::σ70, plus σ70 strains were RL1374 or RL1390 (both contain additional, chromosomally encoded σ70). All measurements are the averages of at least three determinations. The methods for determining phenotypes and plating efficiencies are in the Supplemental Material
The number of plaques formed by λcIc17 (requires E. coli nus functions; Friedman et al. 1976) on β′::σ70 strains divided by the number of plaques formed on a wild-type strain
EOP on rich medium of β′::σ70 strains at 45°C divided by EOP at 37°C
EOP on minimal medium containing Arg (requires σN-directed transcription of glnA) divided by EOP on Gln-containing medium (allows σN-independent growth)
The swarm diameter of β′::σ70 strains on motility agar plates divided by the swarm diameter of a wild-type strain. Flagella synthesis requires σF function
Observation of O2 evolution upon addition of 3% H2O2 to stationary-phase cultures; requires σS-dependent expression of catalase from kat