FIG 4.

Complementation of ΔCD1492 and site-directed mutagenesis of conserved sensor kinase residues. Sporulation frequencies calculated from the ratios of spores to vegetative cells by phase-contrast micrographs obtained at H₂₄ (black bars) or from cells before and after treatment with ethanol (gray bars). Strains 630Δerm pPcpr (MC282, vector control), 630Δerm pPcprA::CD1492 (MC587), ΔCD1492 pPcpr (MC729, vector control), ΔCD1492 pPcprA::CD1492 (MC730), and ΔCD1492 pPcprA::CD1492-H668A (MC771) were grown on 70:30 sporulation agar plates supplemented with 2 μg ml⁻¹ thiamphenicol and 1 μg ml⁻¹ nisin, and sporulation frequency assays were performed as described in Materials and Methods. The mean values and the standard errors of the means of at least four biological replicates are shown. *, P ≤ 0.05 by two-tailed Student t test.