FIG. 4.

AI-2 modulates flagellar gene transcription. Transcript levels of flgS, fliA, flgM, and flaA (A) and of flhA (B) were determined by qRT-PCR normalized to the levels of ureA in each of the genotypes indicated and are represented as the log₂ difference relative to the levels in the wild-type strain. Levels of the same transcripts were determined in the indicated genotypes and normalized to the levels of the 16S rRNA gene in each sample (C). AI-2 activity in CFS from wild-type early-stationary-phase H. pylori was measured relative to different concentrations of DPD (D). flhA transcript levels were measured as in panel B in wild-type and ΔluxS cultures untreated or treated for 4 h with 0.1 mM DPD (E) and in ΔluxS cultures treated with a range of DPD concentrations (F). Error bars indicate the standard deviations for three triplicate samples.