Figure 5

luxS _Hp /DPD modulates H. pylori flagellar gene transcription. Transcript levels of (A) flhA, motA, motB; (B) flaB, flgE, flaA; (C) fliI were determined by qRT-PCR normalised to the levels of the 16 S rRNA gene. (D) Relative expression of ureA was utilised as a non-flagella gene control. The Y axis shows the relative transcriptional level of each gene in each strain normalised to the level of the same gene in the strain control (which is J99 wild-type in every case). Values are mean activities of triplicate RNA samples of each strain. Transcript levels were measured in wild-type and ΔluxS_Hp cultures grown with or without DPD (150 μM) and in ΔluxS_Hp⁺ cultures grown without DPD. (E) AI-2 activity (using the previously-described V. harveyi BB170 bioluminescence assay [4]) in DPD solution (at concentrations of 50 μM, 150 μM or 500 μM) and in cell free culture supernatant (24 h) of H. pylori wild-type, ΔluxS_Hp and ΔluxS_Hp⁺ strains grown in the Brucella broth (starting OD_{600 nm} of 0.05). Negative control is Brucella broth alone. A diluted in vitro synthesised AI-2 sample was utilised as a qualitative positive control [8]. Error bars indicate standard deviation.