TABLE 4.

Effect of deletion of CodY binding site on ilvD expression

GenotypeMediumaDoubling time (min)bCopies of ilvD transcriptc
ilvDp+TSS56.8 ± 2.812.6 ± 1.2
TSS + 16 AA31.0 ± 1.01.1 ± 0.6
ilvDpΔCBSTSS53.0 ± 5.823.8 ± 2.2
TSS + 16 AA36.0 ± 1.812.0 ± 2.1
codY::(erm::spc)TSS58.0 ± 2.6115.6 ± 2.0
TSS + 16 AA37.9 ± 1.8420.8 ± 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).