Pikromycin production stimulation through antibiotic down-regulatory gene disruption in Streptomyces venezuelae

The wblA gene, which encodes a whiB-like putative transcription factor, has been widely reported as an antibiotic biosynthesis down-regulator in Streptomyces coelicolor. The wblA ortholog from Streptomyces venezuelae was identified by sequence alignment with wblA from S. coelicolor. To determine the biological significance of wblA from S. venezuelae, chromosomal disruption of the wblA (sve) gene was performed by homologous recombination using the pKC1139 vector. The phenotypic difference between S. venezuelae and S. venezuelae Delta wblA (sve) was shown, and pikromycin production was quantified by HPLC analysis. Production of pikromycin by S. venezuelae Delta wblA (sve) was approximately 3.5-fold higher compared to that by S. venezuelae. To further show that the wblA (sve) gene was implicated in pikromycin production, wblA (sve) was cloned into Streptomyces integrative expression vector, which was independently introduced into both S. venezuelae and S. venezuelae Delta wblA (sve) by conjugation. HPLC analysis of complementation and overexpression strains showed an approximately 2.5-fold reduction in pikromycin production by the wblA (sve) overexpression mutant.