DepR1, a TetR Family Transcriptional Regulator, Positively Regulates Daptomycin Production in an Industrial Producer, Streptomyces roseosporus SW0702

Daptomycin is a potent cyclic lipopeptide antibiotic. It is widely used against various Gram-positive bacterial pathogens. Historically, a poor understanding of the transcriptional regulation of daptomycin biosynthesis has limited the options for targeted genetic engineering toward titer improvement. Here, we isolated a TetR family transcriptional regulator, DepR1, from the industrial producerStreptomyces roseosporus SW0702 using a biotinylateddptE promoter (dptEp ) as a probe. The direct interaction between DepR1 anddptEp then was confirmed by electrophoretic mobility shift assays and DNase I footprinting assays. The deletion ofdepR1 led to a reduction indptEp activity and the cessation of daptomycin production. TheΔdepR1 mutant produced less red pigment and failed to sporulate on R5 medium. This suggests that DepR1 plays a positive role in the control of morphological differentiation. Moreover, DepR1 was positively autoregulated by directly binding to its own promoter. This might account for the positive feedback regulation of daptomycin production. Based on these positive effects, genetic engineering by overexpression ofdepR1 raised daptomycin production and shortened the fermentation period both in flask and in fermentor.