FIG 4.

Overexpression of phoB leads to the activation of hilE. The wild-type strain is S. enterica serovar Typhimurium SL1344. The mutant tested is the SL1344 strain RL291, which contains a pstS deletion leading to the constitutive activation of phoB. Each strain contained the hilE::lacZY reporter plasmid pMAB69. The strains were grown in LB overnight with shaking, and expression levels were determined by measuring lacZ output as measured by β-galactosidase activity. The experiment is representative of an assay which was repeated in triplicate on three separate days.