Figure 4.

Immunodetection of epitope-tagged proteins in intracellular Salmonella bacteria. Hep-2 cells were infected with the indicated strains and bacteria were allowed to multiply intracellularly for 23 h in a gentamicin protection assay (see Materials and Methods). Cells were lysed and extracts were subjected to electrophoretic separation in a 12% SDS-polyacrylamide gel, which was processed as described in the legend to Fig. 2. (A) Prophage proteins: 1, strain MA7172 (sodCI-30∷3xFLAG Kn^R); 2, strain MA7180 (gtgE-34∷3xFLAG Kn^R); 3, strain MA7192 (gogC-36∷3xFLAG Kn^R); and 4, strain MA7084 (gogB-17∷FLAG Kn^R). (B) Chromosomal proteins. Lanes 1, 3, and 5: strain MA7223 (ilvI3305∷Tn10dTac-cat-43∷3xFLAG Kn^R) and lanes 2, 4 and 6: strain MA7195 (lepB-39∷3xFLAG Kn^R). Material loaded corresponds to 10⁶ cfu (lanes 1 and 2), 10⁵ cfu (lanes 3 and 4), and 10⁴ cfu (lane 5 and 6). Positions and molecular masses (kDa) of protein standards are indicated on the left.