Figure 5.
A, nonglycosylated purified GroP WTA (from strain GN1) restores growth of S. aureus USA300 ΔglpQ under phosphate-limiting conditions. Purified, active GlpQ (+Q), but not heat-inactivated GlpQ (hiQ), improves growth when WTA is the only phosphate source in RPMI-Pi medium. Means represent at least three independent assays done in triplicate. Growth after 6 h is shown. B and C, GlpQ expression is induced under phosphate-limiting conditions. Relative amounts of the glpQ transcript were obtained from RNA extracted from cultures grown for 20 h in RPMI-Pi supplemented with different phosphate concentrations (B) or after a 30-min shock without phosphate (C). Values are given as means and standard deviations (n ≥ 3). Statistically significant differences, calculated using an unpaired two-tailed Student's t test, are indicated as follows: n.s., not significant, p > 0.05; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001.