Isolation and genetic manipulation of the antibiotic down-regulatory gene, wblA ortholog for doxorubicin-producing Streptomyces strain improvement.

Cross-genome comparative transcriptome analyses were previously conducted using the sequenced Streptomyces coelicolor genome microarrays to understand the genetic nature of doxorubicin (DXR) and daunorubicin (DNR) overproducing industrial mutant (OIM) of Streptomyces peucetius. In this previous work, a whiB-like putative transcription factor ( wblA sco) was identified as a global antibiotic down-regulator in S. coelicolor (Kang et al., J Bacteriol 189:4315-4319, ). In this study, a total genomic DNA library of a DXR/DNR-overproducing S. peucetius OIM was constructed and screened using wblA sco as a probe, resulting in the isolation of a wblA ortholog ( wblA spe) that had 95% amino acid identity to wblA sco. Gene disruption of wblA spe from the S. peucetius OIM resulted in an approximately 70% increase in DXR/DNR productivity, implying that the DXR/DNR production in the S. peucetius OIM could be further improved via comparative transcriptomics-guided target gene manipulation. Furthermore, several putative wblA spe -dependent genes were also identified using S. coelicolor interspecies DNA microarray analysis between the S. peucetius OIM and wblA spe-disrupted S. peucetius OIM. Among the genes whose expressions were significantly stimulated in the absence of wblA spe, the overexpression of a conserved hypothetical protein (SCO4967) further stimulated the total production of DXR/DNR/akavinone by 1.3-fold in the wblA spe-disrupted S. peucetius OIM, implying that the sequential genetic manipulation of target genes identified from interspecies comparative microarray analysis could provide an efficient and rational strategy for Streptomyces strain improvement. [ABSTRACT FROM AUTHOR]