FIG 4.
High arabinose induction concentrations or constitutive expression of the AraE transporter is sufficient to prevent Spot 42 repression of the araBAD promoter. (A) β-Galactosidase activity assays of PBAD-recA-lacZ expression in JC1005 harboring a plasmid encoding Spot 42 in the presence of 100 μM IPTG and increasing doses of arabinose (0.0002%, 0.002%, and 0.02%). (B) β-Galactosidase activity assays of recA-lacZ expression in a strain constitutively expressing the low-affinity high-capacity arabinose transporter AraE (JC1095) with the Spot 42 plasmid in the presence of 100 μM IPTG and increasing doses of arabinose (0.0002%, 0.002%, and 0.02%). Biological triplicates were assayed, and data are plotted as means ± SEMs. Results of assays are expressed in Miller units.