Figure 4.

Dynamics of gene expression of known mutants in liquid minimal medium containing glucose and acetate: (A) The expression profile of the acs luciferase reporter plasmid shows that acs expression is induced when glucose is exhausted. (B) The acs expression profile using GFP as a reporter is identical to the profile observed with luciferase (A). (C) acs expression is completely absent in crp and cyaA strains. cAMP added to the medium (5 mM) at the beginning of the experiment complements the cyaA strain but glucose repression is maintained. (D) Low expression of acs in the crr and ptsI strains. cAMP added to the medium at the beginning of the experiment directly complements the ptsI strain during growth on glucose, whereas the crr strain only responds once glucose is exhausted. (E) In the ptsG mutant, acs induction is delayed because glucose is consumed more slowly. Moreover, acs expression during glucose consumption is much stronger than in the WT strain. The glycolysis mutants pgi and pfkA also grow more slowly, but acs expression remains low in exponential phase. (F) The expression profiles of the ihfA and ihfB strains show stronger acs expression than the WT during growth on acetate. The highly similar expression kinetics of the two mutants (with genes located at different sites on the chromosome) shows the high internal consistency of the method.