FIG. 4.

(A) fliA51::Tn5 and flhC4::Tn5 reduce hilA and invasion gene expression. β-Galactosidase activity for each fusion is expressed as a percentage of its activity in a wild-type SL1344 background. Average percentages were calculated by using at least two values. Error bars represent the standard deviation of normalized values. (B) Effects of fliA51::Tn5 and flhC4::Tn5 on hilA expression are complemented by expression of E. coli fliZ. pFliZ is pDSM29, pFliY is pDSM30, and pFliZY is pDSM32. fliZ, fliY, or fliZY expression was induced by growing cultures in LB medium containing 10 mM IPTG under oxygen-limiting conditions. β-Galactosidase activity is expressed as Miller units. Averages were calculated by using four or more values from at least two different experiments. Error bars represent the standard deviations.