The Transcriptional Regulator DhyR Positively Modulates Daptomycin Biosynthesis in Streptomyces roseosporus.

Daptomycin (DAP) is a cyclic lipopeptide antibiotic produced by Streptomyces roseosporus, and its biosynthesis is precisely regulated by a complex regulatory network. Although the biosynthetic pathway of DAP has been elucidated, the regulatory mechanism governing its biosynthesis at the transcriptional level is not yet fully understood. In the present study, a new transcriptional regulator, DhyR, was identified. A deletion mutant of dhyR was constructed using the CRISPR-Cas9 tool to elucidate the biological role of DhyR thanks to functional and transcriptomic analyses. The results demonstrated that DhyR positively regulates DAP biosynthesis in S. roseosporus. The in-frame deletion of the dhyR gene resulted in a significant downregulation of the transcription levels of all structural genes within the DAP biosynthetic gene cluster and a significant decrease in DAP yield. In contrast, overexpression of dhyR enhanced the transcription levels of the DAP biosynthetic gene cluster, leading to a 23% increase in DAP yield. Deletion of dhyR caused significant changes in the expression of multiple genes involved in carbohydrate metabolism, energy metabolism and amino acid metabolic pathways through transcriptome analysis. Especially, deletion of dhyR led to a significant downregulation of transcription levels of three DAP biosynthesis-associated genes, including atrA, depR1 and ssig-05090. In summary, DhyR positively regulates DAP biosynthesis in S. roseosporus by influencing the expression of the DAP gene cluster and modulating precursor flux. It functions as a pleiotropic regulator of primary and secondary metabolism in S. roseosporus.