FIG 4.

InvS regulates Salmonella effector secretion and translocation. (A) Expression and secretion of invasion-related effectors in Salmonella WT, ΔinvS, ΔinvS/pinvS, and ΔinvA strains. Bacterial strains were grown under SPI-1-inducing conditions and equal amounts of bacterial lysates or culture supernatants were analyzed by Western blotting. (B) Quantification of protein expression in panel A. Protein levels in the WT strain were defined as 1. Values represent relative protein levels after normalization with the expression in the WT. Data are representative of three experiments. (C) HeLa cells were infected with various Salmonella strains carrying a plasmid expressing the SipA-TEM fusion protein. Fifteen minutes after the infection, cells were loaded with CCF4-AM and incubated at room temperature for 2 h. The translocation efficiency was evaluated under a fluorescence microscope. (D) Western blot showing the expression of SipA-TEM in different strains. (E) Quantification of SipA-TEM translocation. Percentages of blue cells were used to measure the translocation efficiency. The data shown were obtained from three independent experiments. Standard deviations are shown. P values were calculated using the Student t test.