Fig 4.
Effect of the F72A and L76A mutations on the export function of FliJ. (A) Motility (left panel) and secretion assays (right panel) of a ΔfliJ mutant harboring pTrc99AFF4 (V), pMM404 (pTrc99AFF4/wild-type FliJ, indicated as FliJWT), pTIJ105 [pTrc99AFF4/FliJ(F72A), indicated as F72A], or pTIJ106 [pTrc99AFF4/FliJ(F76A), indicated as F76A]. The plates were incubated at 30°C for 4.5 h. Immunoblotting with polyclonal anti-FlgD or anti-FliJ antibody of whole-cell (Cell) and culture supernatant (Sup) fractions prepared from the above transformants. (B) Motility (left panel) of and FlgD secretion (right panel) by a ΔfliH-fliI-fliJ flhB(P28T) mutant transformed with the above plasmids. The plates were incubated at 30°C for 8 h. The level of FlgD secretion was analyzed by immunoblotting with the polyclonal anti-FlgD antibody. The expression level of FliJ was detected by immunoblotting with polyclonal anti-FliJ antibody.