TABLE 4.
Effect of deletion of CodY binding site on ilvD expression
| Genotype | Mediuma | Doubling time (min)b | Copies of ilvD transcriptc |
|---|---|---|---|
| ilvDp+ | TSS | 56.8 ± 2.8 | 12.6 ± 1.2 |
| TSS + 16 AA | 31.0 ± 1.0 | 1.1 ± 0.6 | |
| ilvDpΔCBS | TSS | 53.0 ± 5.8 | 23.8 ± 2.2 |
| TSS + 16 AA | 36.0 ± 1.8 | 12.0 ± 2.1 | |
| codY::(erm::spc) | TSS | 58.0 ± 2.61 | 15.6 ± 2.0 |
| TSS + 16 AA | 37.9 ± 1.84 | 20.8 ± 5.0 |
a
TSS, minimal glucose medium with NH4Cl as the nitrogen source; TSS + 16 AA, a mixture of the branched-chain l-amino acids isoleucine, leucine, and valine in addition to a mixture of 13 amino acids shown previously to enhance CodY binding activity in vivo.
b
Data represent averages for at least two biological replicates ± standard errors of the means.
c
Copies of ilvD transcript per 106 copies rrnA transcript (mean ± standard error of the mean for at least two biological replicates). Student's t test was used to determine statistical significance (P < 0.05).