Fig 7. The virB promoter activity is decreased in the lovhk::km mutant in B. abortus.

A. The virB promoter activity was assessed using a transcriptional fusion of the virB promoter to lacZ. B. abortus 2308 wt and the isogenic lovhk::km, ∆lovR and ∆phyR mutant strains were transformed with pBBR-prom-virB-lacZ replicative vector. Bacteria were cultured in TSB until stationary phase, and β-galactosidase activity was assessed at different time points. Color code: B. abortus 2308 wt (black), lovhk::km (blue), ∆lovR (red), ∆phyR (green), wt + e.v. (grey) and lovhk::km/pMR_lovhk (orange). B. The B.abortus 2308 wt, lovhk::km and lovhk::km/pMR_lovhk strains transformed with the pBBR-prom-virB-lacz vector were cultured in TSB and β-galactosidase activity was assessed at exponential and pre-stationary phases. In both experiments the wt strain transformed with pBBR-lacZ empty vector was used as a negative control (wt + e.v.). Data of both panels are reported in Miller Units as mean ± standard deviation of two biological samples from one representative experiment. Both experiments were repeated three times with similar results. p-values between each strain and wt were determined by one-way ANOVA and post-hoc Tukey’s multiple comparisons test (** = p<0.01, *** = p<0.001). Color code: B. abortus 2308 wt (black), lovhk::km (blue), wt + e.v. (grey) and lovhk::km/pMR_lovhk (orange).