TABLE 4.
Influence of CRP binding site position on CRP coactivation of rhaSR
| Φ(rhaS-lacZ) promoter truncation | Avg β-galactosidase activity (Miller units) in straina: |
||
|---|---|---|---|
| ΔrhaSR | ΔrhaS rhaR+ | Δ(rhaSR) prhaS+ | |
| Φ(rhaS-lacZ)Δ85 | 0.20 | 6.9 | 7.4 |
| Φ(rhaS-lacZ)Δ128 | 0.38 | 216 | 31 |
| Φ(rhaS-lacZ)CRP−2 | 0.40 | 4.3 | 1.1 |
| Φ(rhaS-lacZ)CRP−3 | 0.15 | 7.1 | 26 |
a
β-Galactosidase activity was measured from single-copy lacZ fusion strains grown in MOPS-buffered minimal growth medium containing ampicillin and l-rhamnose. The CRP−2 and CRP−3 constructs replaced the native CRP site (20 bp upstream of the RhaR binding site) with the same sequence 2 or 3 bp upstream as described in the text. The standard errors were less than 23% of the average activities. The strain background was either ΔrhaS rhaR+zih-35::Tn10 or Δ(rhaSR)::kan. Each strain was transformed with empty vector, pHG165 (26), or plasmid pSE289, which is pHG165 rhaS+ [Δ(rhaSR)prhaS+] (17).