Figure 1.

S. aureus GlpQ cleaves glycerol-type WTA derived from S. aureus PS187, S. lugdunensis, S. epidermidis, S. capitis, and S. intermedius. A, glycerophosphodiesterase activity was measured at pH 9, with 2.5 mm isolated WTA from different staphylococcal species in the presence of 5 mm CaCl₂ and 5 μg of MBP-GlpQ (black bars, +) or MBP alone as a negative control (gray bars, −). Error bars represent standard deviations of at least three independent assays done in triplicate. Significant differences between S. aureus 8325-4– and GroP WTA–type strains were calculated with Student's t test. **, p < 0.01; ***, p < 0.001. B, extracted ion chromatograms of WTAs before (Buffer) and after treatment with MBP-GlpQ; the GroP standard was analyzed by LC/MS. Diagrams show calculated (c.m.) and observed masses (o.m.) of GroP. The chromatograms of all WTA samples without incubation with MBP-GlpQ (Buffer) overlap.