FIGURE 1.

Cytotoxicity of indicated strains and the role of PA4916 in the expression and secretion of ExoS. (A,B) HeLa cells were infected with indicated strains at a MOI of 50. Three hours post infection, cells attached to the 24-well plate were washed with PBS and stained with crystal violet. The cell associated crystal violet was dissolved in ethanol and quantified by measuring OD₅₉₀. HeLa cells with no bacterial infection served as a control. (C) Bacteria were cultured to an OD₆₀₀ of 1.0 in LB with or without 5 mM EGTA. Proteins in supernatants and pellets from equivalent bacterial cells were loaded onto SDS-PAGE gels and probed with an antibody against ExoS or RNA polymerase beta subunit. S, supernatant; P, pellet.