FIG. 7.

Zymographic analysis of S. aureus strains with or without an intact rsbU gene. Extracellular proteins were isolated from stationary-phase culture supernatants, and 15 μg of each sample was separated in an sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel containing 1.0 mg of M. luteus cells/ml, followed by overnight incubation at 37°C in a buffer containing Triton X-100 and staining with methylene blue. This zymogram is representative of results obtained from three independent experiments. Molecular mass markers are indicated in kilodaltons to the left of the gel. Lane numbers correspond to 8325-4 (rsbU-negative; lane 1), SH1000 (rsbU⁺; lane 2), IK184 (ΔrsbUVWsigB; lane 3), and Newman (rsbUVWsigB⁺; lane 4).