“…Consequently, WT CO92 and ⌬ail single, ⌬lpp ⌬msbB double, and ⌬lpp ⌬msbB ⌬ail triple mutant cultures grown overnight were diluted 1:20 and grown in either HIB or calcium-depleted modified M9 medium (42 mM Na 2 HPO 4 , 22 mM KH 2 PO 4 , 8.6 mM NaCl, 18.6 mM NH 4 Cl, 0.001 mg/ml FeSO 4 , 0.0001% thiamine, 1 mM MgSO 4 , 0.4% dextrose, and 1% Casamino Acids) at 28°C with shaking (180 rpm) for 3 h and then at 37°C for 2 h. When the bacteria were grown in HIB, 5 mM EGTA (Sigma-Aldrich, St. Louis, MO) was added to trigger the low-calcium response 5 min before harvesting of the cultures. Aliquots of the cultures grown in either medium (representing similar CFU) were removed, and 1 ml of the supernatants was precipitated with 55 l of 100% trichloroacetic acid (TCA) on ice for 2 h. The TCA precipitates were dissolved in SDS-PAGE buffer and analyzed by immunoblotting with antibodies to YopE, LcrV (Santa Cruz Biotechnology, Santa Cruz, CA), and YopH (Agrisera, Stockholm, Sweden) (49,55,57). The anti-DnaK monoclonal antibody (Enzo) was employed to probe bacterial pellets to ensure that the bacterial supernatants were obtained from similar numbers of bacteria across the tested strains.…”