FIG. 4.

Effect of loss-of-function mutation in sicA on levels of type III secreted proteins InvJ, SipA, and SipD. Whole-cell lysate and culture supernatant proteins from wild-type S. enterica serovar Typhimurium and isogenic sicA mutant derivatives were probed for the presence of the different proteins, as indicated by Western immunoblotting with antibodies directed to the proteins or their epitope tags as appropriate (see Materials and Methods). Lane control, sample from an otherwise identical S. enterica serovar Typhimurium strain that does not express the M45-SipD epitope-tagged protein.