FIG. 1.

InvB is required for SopE secretion. A Salmonella serovar Typhimurium strain carrying a chromosomal copy of M45 epitope-tagged sopE (wild type) and isogenic derivatives carrying deletion mutations in sicP or invB were grown under SPI-1-TTSS-inducing conditions (5). The presence of SopE-M45 in whole-cell lysates and culture supernatants was evaluated by Western immunoblot analysis using a monoclonal antibody directed to the M45 epitope as previously described (11). A complementing arabinose-inducible plasmid, pBAD-invB, was introduced into the ΔinvB mutant strain, and whole-cell lysates and culture supernatants of the strain grown under inducing conditions (in the presence of 0.02% arabinose) were prepared under identical conditions.