FIG. 2.
Expression and secretion of ExoS protein. (A) Comparison of cellular and secreted forms of ExoS in strains PAK and PAKmucA22 grown in LB or LB plus 5 mM EGTA. Supernatants and pellets from equivalent bacterial cell numbers were loaded onto sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and immunoblotted with anti-ExoS antibody. Both ExoS and ExoT are indicated by the arrow. Anti-ExoS polyclonal antibody also recognizes ExoT due to high homology between these two proteins. (B) Expression of exsA::lacZ (pHW0032) in the backgrounds of PAK, PAKmucA22, and PAKmucA22algR::Gm with or without the mucA clone driven by an algU promoter (pWW020) or lac promoter (pWW021). (C) Expression of exoS::lacZ (pHW0005) in the same backgrounds as described above. Bacteria were grown to an OD600 of 1 to 2 in LB with (black bars) or without (white bars) EGTA before β-galactosidase assays.