Fig. 5

Lys32 of Salmonella FlgE is important for hook assembly. a Motility in soft tryptone agar of an S. enterica ΔflgE null mutant strain that harbored plasmids carrying genes encoding the wild-type FlgE protein, a FlgE K32A mutant protein, or a FlgE K32A D62Y double-mutant protein. The plate was incubated for 10 h at 30 °C. Western blot analysis using polyclonal antibodies towards FlgE (b and d) and FliC (c and e) proteins exported into the culture supernatant broth (b and c) or in the cell pellet fractions after centrifugation (d and e). The bacteria were grown in LB to early stationary phase at 37 °C. Relative band densities (%) compared to FlgE wild-type are indicated. FliC is 51 kDa and wild-type FlgE is 42 kDa. An asterisk in (e) indicates a non-specifically bound protein. Box plot (f) displaying the distribution of the numbers of flagella per cell, for > 30 cells, and electron micrograph images of cells synthesizing the FlgE K32A mutant protein (g) or the FlgE K32A D62Y double-mutant protein (h). Bars, 1 μm