FIG. 7.

Inducing the Cpx pathway alters flagellin expression (phase variation) in a Cpx/RdoA-dependent fashion. 2D gel analysis of the flagellins expressed in serovar Typhimurium under NlpE-inducing and noninducing conditions shows that the primary flagellin produced in wild-type cells containing pBAD18 is FliC (A). In wild-type cells containing pND18 (expressing NlpE), the flagellin switches to primarily FljB (B). In the absence of rdoA, cells containing pND18 revert to producing much less FljB (C) while cells containing pBAD18 also express predominately FliC (D). All cultures were grown in the presence of 0.2% arabinose for 2 h after addition at an OD₆₀₀ of 0.6. Two additional protein spots, GroEL and Trigger factor, identified by mass spectrometry, are also indicated for comparison. Because small variations in total protein loading and staining can affect the overall spot intensity, it is important to compare the ratios of FljB to FliC in each gel rather than spot intensity.