TABLE 4.
Some alterations in the nucleotide sequence of boxA that do not alter the TnaC amino acid sequence result in constitutive expression of the tna operona
| Strain | tnaC codons | β-Gal activity (Miller units)
|
Ratiob | |
|---|---|---|---|---|
| −Trp | +Trp | |||
| SVS1144 (wild type) | AUG.......CGC23CCU24UGA... | 520 ± 25 | 14,830 ± 1,495 | 29 |
| VK2400 | CGA23 | 360 ± 24 | 5,000 ± 995 | 14 |
| VK2500 | CGU23 | 250 ± 19 | 4,260 ± 720 | 17 |
| PDG1178 | CGG23 | 1,730 ± 85 | 17,860 ± 557 | 10 |
| VK3000 | AGA23 | 3,335 ± 260 | 10,080 ± 1,533 | 3 |
| VK3100 | AGG23 | 1,560 ± 231 | 8,520 ± 879 | 5 |
| VK2600 | CCA24 | 710 ± 66 | 5,670 ± 979 | 8 |
| VK2700 | CCG24 | 570 ± 112 | 5,970 ± 1,035 | 10 |
| PDG1172 | ACU24(Thr) | 150 ± 19 | 1,320 ± 245 | 9 |
| PDG1173 | UCU24(Ser) | 265 ± 25 | 1,250 ± 214 | 5 |
a
Cultures were grown as for Table 2. More than five cultures of each type were assayed in each case. CGA, CGU, CGG, AGA, and AGG are all Arg codons. CCA and CCG are Pro codons. The nucleotide changes introduced are underlined.
b
Ratio of activities for cultures grown with Trp and without Trp.