Fig. 7.
Multicopy expressions of lhrA and hexS inhibit prodigiosin biosynthesis and flhDC expression in the hexS mutant. (a) Prodigiosin pigmentation of strains grown on LB agar with kanamycin for 20 h at 30 °C. Plasmids with the hexS or lhrA genes under control of the Plac promoter inhibit pigmentation in both the wild-type and the ∆hexS mutant. Experiments were performed with the PIC3611 strain background and vector indicates pMQ131. (b) β-Galactosidase activity produced by WT and ∆hexS strains bearing a plasmid-borne flhDC-lacZ transcriptional reporter after growth in LB medium to OD600 3. A representative experiment with three independent biological replicates is shown. Mean and standard deviation is shown. (c) Model, described in Discussion, for coordinated regulation of secondary metabolite biosynthetic genes (pigA-N and swrW) and the prtS protease gene by EepR and HexS. The line between EepR and HexS indicates that each inhibits transcription of the other.