Figure 2.

Regulation of STE expression. S. typhimurium wild-type or regulatory mutants expressing transcriptional fusions of STE genes to firefly luciferase in the pGPLFR03 expression vector were grown overnight in LB and back diluted in SPI2-inducing conditions (A) or SPI1-inducing conditions (B), and firefly luciferase activity was determined and normalized for cell number by dividing by the activity of the constitutively expressed Renilla luciferase. sspC∷Tn5-lacZY expression is presented as Miller units (as a control for SPI1-regulated gene expression).