The H15A mutation in HPr results in increased resistance to sublancin. (a) The two phosphorylation sites in the HPr protein were mutated individually to alanine residues. The growth curves of the resulting strains are shown, with 200 nM sublancin added at 120 min, as depicted by the vertical line. Blue line, B. subtilis ΔSPβ; gray line, B. subtilis ΔSPβ-H15A; black line, B. subtilis ΔSPβ-S46A; solid line, no sublancin; dashed line, with sublancin. (b) Blue line, B. subtilis ΔSPβ; gray line, B. subtilis ΔSPβ-hprK; black line, B. subtilis ΔSPβ-ccpA; solid line, no sublancin; dashed line, with sublancin. The ΔccpA and ΔhprK mutations have no effect on the sensitivity of the cells to sublancin. Sublancin at 200 nM was added at 120 min. The means of the data from one experiment conducted in triplicate are shown. The data are representative of the results from three independent experiments.