Figure 5. Ectopic expression of fimL inhibits exoT transcription.

All strains harbor the PexoT-lacZ transcriptional reporter fusion integrated at the CTX site as a readout for transcription of the T3SS and either include p (vector only) or pfimL-FL (vector with fimL-3X-FLAG). β-galactosidase activity was measured in the presence or absence of Ca²⁺ in the indicated mutants in (A) PAO1 or (B) PA103. Shown is the mean of 12 data points from 3 or 4 experiments. Error bars indicate SD. (***) P<0.001 compared to the respective strain containing vector only grown in the absence of Ca²⁺.