Figure 11

SapS phosphatase activity depends on the D103 residue and is neither implicated in the intramacrophage survival potential nor infectivity of S. aureus in zebrafish. (A) Cells of S. aureus SA564 (black), SA564 ΔsapS (blue), SA564 ΔsapS + pLI50_SapS-Spot (dark grey) and SA564 ΔsapS + pLI50_SapS_D103A-Spot (light grey) were grown in TSB at 37 °C until exponential phase, centrifuged, lysed and total crude extracts were used for phosphatase activity assays on PNPP. Data are presented as mean + SD of three biological replicates. **, p < 0.01; *** (Mann–Whitney U test). (B) Survival of S. aureus in infected macrophages. Survival rates are expressed as a percentage of the intracellular bacterial cell counts that were obtained immediately after the gentamicin/lysostaphin treatment, which was fixed to 100%. The data are presented as box and whisker plot showing the interquartile range (25–75%, box), the median (horizontal line) and the standard deviation (bars) of 4 different experiments. **, p < 0.01 (Ordinary two-way ANOVA test). (C) Kaplan–Meier representation of the survival of zebrafish embryos infected by injection into the duct of Cuvier with at 3 × 10² CFU/nL cultured in exponential phase, or PBS (negative control) The proportion of surviving embryos (n = 50 for each, indicative of three separate experiments) is employed to express the results. **, p < 0.01, ns, not significant (Log-rank Mantel–Cox statistical test). hpi, hours post-infection.