Figure 4
The expression of the hly II operon of J96 responds to the external levels of zinc. (a) Transcriptional expression from the hly II promoter in cultures of the strains JFV3 and its zur::CmR mutant derivative (EV46) grown in M-LB and M-LB replenished with either 1 or 10 μM ZnCl2. Culture samples were taken at late-log growth phase (OD600 nm of 1.0). β-galactosidase activity (expressed in Miller units) was determined from three independent cultures; mean values with standard deviation are plotted. *P < 0.05, ANOVA with Tukey’s multiple comparisons test (b) Growth curves of JFV3 strain cultured in M-LB and in M-LB replenished with 10 μM ZnCl2. Growth was monitored by measuring OD600 nm from two independent cultures; mean values are plotted.(c) Detection of the α-hemolysin in secreted protein extracts from cultures of J96, JFV21 (J96ΔI) and JFV16 (J96ΔII) strains and their otherwise isogenic zur mutants (EV27, EV34 and EV38) grown in M-LB and M-LB replenished with 10 μM ZnCl2. Full-length gel images are shown in Fig. S8.
