Figure 8.

The sufficient concentration of cAMP restores cas3 promoter activity reduced by the mutation of GCS. (A) The β-gal activity of the cas3 promoter was measured by reporter plasmids in WT, ΔgcvP, or Δcrp cultured in LB media supplemented with 0, 5, 7, 9, 11, 13, or 15 mM cAMP. The addition of excess cAMP resulted in a significant increase in cas3 promoter activity in WT and ΔgcvP. The cas3 promoter activity in both WT and ΔgcvP reached the same level. (B) The β-gal activity of crp promoter was measured by reporter plasmids in WT (EC13) or ΔgcvP (EC23). In both WT and ΔgcvP, gene crp expression remained at the same level. All the data were mean ± SEM of at least three replicates, and the p value (p < 0.05) was analyzed by the t-test.