TABLE 5.
Combining a deletion of the presumed rut site with a point mutation in the boxA-like region results in near-maximum expression of the tna operon; tnaC translation is required for constitutive expressiona
| Strain | tnaC codon and spacer region nt | β-Gal activity (Miller units)
|
Ratiob | |
|---|---|---|---|---|
| −Trp | +Trp | |||
| (nt 101–123) | ||||
| SVS1144 (wild type) | AUG1...CGC23CCU24UGAU(UU..CC...CC...C..CCA)... | 410 ± 32 | 12,890 ± 1,268 | 31 |
| VK1800 | Δ(nt 101–123) | 3,450 ± 312 | 4,420 ± 698 | |
| VK1800 + bicyclomycin | 3,120 ± 630 | 3,880 ± 330 | ||
| VK2000 | AGC23 Δ(nt 101–123) | 8,970 ± 766 | 9,640 ± 1,027 | |
| VK1900 | UAG1 Δ(nt 101–123) | 480 ± 57 | 480 ± 72 | |
| VK1900 + bicyclomycin | 2,360 ± 65 | 2,320 ± 44 | ||
| VK2100 | UAG1...AGC23 Δ(nt 101–123) | 2,365 ± 154 | 2,320 ± 243 | |
| VK2100 + bicyclomycin | 3,075 ± 200 | 3,100 ± 560 | ||
a
Cultures were grown as for Table 2. More than five cultures of each type were assayed in each case. The nucleotide changes introduced are underlined.
b
Ratio of activities for cultures grown with Trp and without Trp.