TABLE 5.

Effect of deletion of CodY binding site on ybgE expression

GenotypeMediumaDoubling time (min)bCopies of ybgE transcriptc
ybgEp+TSS56.8 ± 2.870.2 ± 9.6
TSS + 16 AA31.0 ± 1.011.8 ± 3.2
ybgEpΔCBS3TSS51.5 ± 1.85,006.8 ± 1,470.7
TSS + 16 AA33.6 ± 0.17,576.4 ± 2,512.7
codY::(erm::spc)TSS58.0 ± 2.61976.1 ± 6.8
TSS + 16 AA37.9 ± 1.841,723.6 ± 23.6
  • 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 the averages for at least two biological replicates ± standard errors of the means.

  • c Copies of ybgE 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).