Figure 5. The dksA promoter is subject to stringent and growth rate-dependent control.

A,B,C: Primer extension was performed on RNA isolated from wild-type (wt) or ΔdksA strains containing promoter-lacZ fusions (see Table 1). (A) PdksA (wt, RLG10101; ΔdksA; RLG10103), (B) rrnB P1 (wt, RLG4996; ΔdksA, RLG6348), (C) lacUV5 (wt, RLG4998; ΔdksA, RLG8950). RNA was isolated at varying times after addition of serine hydroxamate and processed using the same primer hybridizing to lacZ for each promoter construct (see Experimental Procedures). Error bars shown are from 3 independent experiments. D,E,F: Growth rate-dependence of PdksA and rrnB P1 promoter-lacZ fusions in strains wild-type or mutant for dksA. (D) PdksA (wt, RLG10101; ΔdksA; RLG10103) (E) rrnB P1 (wt, RLG4996; ΔdksA, RLG6348). (F) Promoter activities normalized to 1 at 0.4 doublings/hr to facilitate comparison of the slopes determined in (D) and (E), as described in Experimental Procedures. The media used to vary the growth rates were (◆,◇) LB; (■,□) MOPS minimal medium supplemented with 0.4% glycerol, 0.4% casamino acids, 40 μg/ml tryptophan, and 10 μg/ml thiamine; (●,○) MOPS with 0.4% glycerol, all 20 amino acids (80 μg/ml each except 40 μg/ml for tryptophan and tyrosine), and 10 μg/ml thiamine; (▽) MOPS with 0.4% glycerol and 10 mg/ml thiamine.