FIG. 5.

Alcaligin inducer requirement of the AlcR(S103T) mutant protein produced from the alcR(S103T) mutant allele borne on a multicopy plasmid. (A) alcA::mini-Tn5 lacZ1 transcriptional activities were monitored in strain BRM13 complemented with wild-type and mutated alcR⁺ plasmids constructed by overlap extension PCR. β-Galactosidase activities were measured for cells cultured in iron-replete SS medium (solid bars), iron-depleted SS medium (open bars), or iron-depleted SS medium supplemented with 20 μg of purified alcaligin/ml (hatched bars). β-Galactosidase activities are expressed in Miller units (mean ± 1 standard deviation; n = 3). (B) The relative degree of constitutivity of AlcR is depicted as in Fig. 2B. Multicopy alcR⁺ plasmids: Bp wt, pRK/N_pC_p; Bb wt, pRK/N_bC_b; Bb S103T, pRK/Bb-S103T.