TABLE 3.
ilvBΔT-lacZ fusion activity in codY point mutantsa
| Growth medium | Strain (genotype or substitution in CodY) | Μean β-galactosidase sp act ± SD (fold derepression)b | % of codY null activity |
|---|---|---|---|
| With BCAAs | PJB14 (Wild-type) | 46 ± 15 (1) | 6 |
| PJB15 (codY) | 722 ± 77 (15.7) | 100 | |
| BB2611 (R61A) | 490 ± 67 (10.7) | 68 | |
| BB2613 (R61E) | 649 ± 52 (14.1) | 90 | |
| BB2619 (R61K) | 436 ± 77 (9.5) | 60 | |
| BB2614 (F71A) | 199 ± 39 (4.3) | 28 | |
| BB2615 (F71R) | 649 ± 101 (14.1) | 90 | |
| BB2616 (F71E) | 685 ± 67 (14.9) | 95 | |
| LH12 (F40A) | 671 ± 35 (14.6) | 93 | |
| LH7 (F98A) | 609 ± 33 (13.2) | 84 | |
| Without BCAAs | PJB14 (Wild-type) | 482 ± 43 (1) | 66 |
| PJB15 (codY) | 728 ± 55 (1.5) | 100 | |
| BB2611 (R61A) | 628 ± 64 (1.3) | 86 | |
| BB2613 (R61E) | 683 ± 49 (1.4) | 94 | |
| BB2619 (R61K) | 658 ± 45 (1.3) | 90 | |
| BB2614 (F71A) | 494 ± 34 (1) | 68 | |
| BB2615 (F71R) | 663 ± 99 (1.3) | 91 | |
| BB2616 (F71E) | 702 ± 43 (1.4) | 96 | |
| LH12 (F40A) | 661 ± 34 (1.4) | 91 | |
| LH7 (F98A) | 629 ± 33 (1.3) | 86 |
a
Cells were grown to mid-exponential phase in TSS minimal medium supplemented with glucose, glutamine, and a 13-amino-acid mixture with or without added BCAAs.
b
β-Galactosidase activities (in Miller units) represent the averages of three samples taken during subsequent exponential growth at OD600 values ranging from 0.2 to 0.9 in three independent cultures. The change in derepression (fold derepression) represents the β-galactosidase activity in a mutant strain divided by the activity in the wild-type strain.