Loss of Hha and YdgT disrupts flagellar biosynthesis at the level of Class II/III activation. (A) Wild type and Δhha ΔydgT whole cell lysates were collected at OD600 ~ 0.4-0.6 and levels of FlhC and FlhD were determined by Western blot analysis. DnaK was used as a loading control. (B) Promoter activity at Class I (flhD), II/III (fliA) and III (fliC) was determined in wild type, Δhha, ΔydgT and Δhha ΔydgT using GFP reporter plasmid constructs. Fluorescence intensity (501/511 nm) was measured after 6 h and normalized to OD600 (RLU/OD600). Data represents means and standard errors from three independent experiments.