Back to article: Basal level of ppGpp coordinates Escherichia coli cell heterogeneity and ampicillin resistance and persistence

FIGURE 3: High basal ppGpp and thus low growth rate did not produce more ampicillin persistent cells. (A) Growth dynamics of the spoT202 and spoT203 strains. For comparison, the growth curves of the wt, ΔrelA and ppGpp0 strains from Figure 2A were included. Four biological replicates were performed, and the averages and SDs are shown. spoT202, ΔrelA spoT (T78I) [47]; and spoT203, ΔrelA spoT (R140C) [47]. (B) Thin layer chromatography analysis of the intracellular ppGpp levels in the five exponentially growing strains as labeled with 32p-orthophosphate in the MOPSr-Lp medium. GTP, ppGpp and pppGpp are indicated. Unknown molecules nearby the ppGpp are framed in broken-line rectangles. (C) Quantification of the ppGpp levels as in panel (B). Two biological replicates were performed, and the average and SD are shown. (D) The ampicillin (250 μg/ml) killing curves of the studied strains. Three biological replicates of both spoT202 and spoT203 were performed, and the averages and SDs are shown. For comparison, the same killing curves of the three strains from (Figure 2B) were included.

47. Sarubbi E, Rudd KE, Cashel M (1988). Basal ppGpp level adjustment shown by new spoT mutants affect steady state growth rates and rrnA ribosomal promoter regulation in Escherichia coli. Mol Gen Genet 213(2-3): 214-222. 10.1007/BF00339584

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