FIG 3.

The promoters of the SPI-1 activators, hilC and rtsA, are differentially regulated by growth at 42°C. (A) The promoters of hilC, rtsA, and hilD were cloned into the pSP417 multicopy shuttle vector (empty vector) upstream of a promoterless lacZ gene. Bacteria were grown as described for Fig. 1B and diluted 1:50 into LB-MOPS medium with 1 mM glucose at pH 7.4 at 37°C or 42°C. β-Galactosidase activity was measured after overnight growth. Data are from 4 separate experiments, and a statistically significant result compared to activity at 37°C was determined. The strains used were BTNC0002 to BTNC0005. (B) Bacteria were grown in LB-MOPS medium with 1 mM glucose at pH 7.4 at 37°C or 42°C. Total RNA was extracted at an OD₆₀₀ of ∼1. cDNA was generated using gene-specific primers, and expression data were normalized to the rrsA 16S rRNA gene.