MglA and SspA effects on ripA and iglA expression. Mid exponential phase cultures of the indicated transcriptional lacZ reporter strains cultured in Chamberlains defined media were assayed for β-galactosidase activity in replicates of three and reported as mean Miller units ± standard deviation. (a) F. tularensis LVS ripA'-lacZ2 expression in wild type (wt), ΔmglA, ΔsspA, and ΔmglAΔsspA backgrounds. In trans complementation (pmglA and psspA) was accomplished using wild type alleles and native promoters cloned into pMP633. F. tularensis LVS pMP633 was used as the vector only control (vector). (b) F. tularensis LVS iglA'-lacZ expression in wild type (wt), ΔmglA, ΔsspA, and ΔmglAΔsspA backgrounds.