FIG. 4.

Polymyxin causes release of periplasmic proteins. The left panel shows the results of osmotic shock (O) as described in Materials and Methods. The right panel shows the results of treatment at the indicated concentration of polymyxin B (PB). In each case, a whole-cell extract (W) was compared to the supernatant from an equivalent number of cells after treatment. Proteins in each sample were separated by SDS-PAGE and subjected to immunoblot analysis with primary antibody directed against the indicated protein. The strains used were JS921, JS922, and JS923.