FIGURE 9.

Contributions of the three putative IHF binding sites to the promoter activity of VflT6SS2 major cluster. (A) The sequences of the three predicted IHF binding sites within the promoter region of VflT6SS2 major cluster and the mutations that we incorporated into each binding site. The nucleotides identical to the E. coli consensus site are in bold. (B) Overnight cultures of V. fluvialis WT and ΔihfA strains containing either pVflT6SS2-lux, pVflT6SS2-lux-ihf1M, pVflT6SS2-lux-ihf2M, pVflT6SS2-lux-ihf3M, or pVflT6SS2-lux-ihf1+2M reporter fusions were diluted 1:100 in LB medium and 200 μl aliquots were transferred to Opaque-wall 96-well microtiter plates. The plates were incubated at 30°C with shaking for measuring the OD₆₀₀ and light units. Luminescence activity is calculated as light units/OD₆₀₀. The data represent three independent experiments. ^∗∗Significantly different from pVflT6SS2-lux (t-test, P < 0.05). ^∗∗∗Significantly different from pVflT6SS2-lux (t-test, P < 0.01).