Search

The transcription factor (TF)‐mediated regulatory network controlling lincomycin production in Streptomyces lincolnensis is yet to be fully elucidated despite several types of associated TFs having been reported. SLCG_2919, a tetracycline repressor (TetR)‐type regulator, was the first TF to be characterized outside the lincomycin biosynthetic cluster to directly suppress the lincomycin biosynthesis in S. lincolnensis. In this study, improved genomic systematic evolution of ligands by exponential enrichment (gSELEX), an in vitro technique, was adopted to capture additional SLCG_2919‐targeted sequences harboring the promoter regions of SLCG_6675, SLCG_4123‐4124, SLCG_6579, and SLCG_0139‐0140. The four DNA fragments were confirmed by electrophoretic mobility shift assays (EMSAs). Reverse‐transcription quantitative polymerase chain reaction (RT‐qPCR) showed that the corresponding target genes SLCG_6675 (anthranilate synthase), SLCG_0139 (LysR family transcriptional regulator), SLCG_0140 (beta‐lactamase), SLCG_6579 (cytochrome P450), SLCG_4123 (bifunctional DNA primase/polymerase), and SLCG_4124 (magnesium or magnesium‐dependent protein phosphatase) in ΔSLCGL_2919 were differentially increased by 3.3‐, 4.2‐, 3.2‐, 2.5‐, 4.6‐, and 2.2‐fold relative to those in the parental strain S. lincolnensis LCGL. Furthermore, the individual inactivation of these target genes in LCGL reduced the lincomycin yield to varying degrees. This investigation expands on the known DNA targets of SLCG_2919 to control lincomycin production and lays the foundation for improving industrial lincomycin yields via genetic engineering of this regulatory network. [ABSTRACT FROM AUTHOR]

Lincomycin industrially produced by Streptomyces lincolnensis can be adopted to treat infections caused by Gram-positive bacteria. SLCG_Lrp, a transcriptional regulator of the Lrp family, was first identified to positively regulate lincomycin biosynthesis. However, the regulatory role of SLCG_Lrp is yet to be elucidated. This study utilized RNA-seq for comparing the transcriptome profile of original-strain LCGL and the ΔSLCGL_Lrp mutant. A total of 244 genes comprising 116 downregulated and 128 upregulated genes were differentially expressed between LCGL and ΔSLCGL_Lrp. An in-depth analysis revealed that SLCG_Lrp promotes nitrate assimilation but inhibits fatty acid metabolism, as well as directly regulates five regulators participating in the modulation of multiple cellular processes. With individual inactivation of those regulatory genes in S. lincolnensis LCGL, we confirmed the FadR transcriptional regulator SLCG_2185 was obviously correlated with lincomycin production and found it to transcriptionally stimulate the lincomycin biosynthetic cluster. Furthermore, SLCG_2185 overexpression in the high-yield S. lincolnensis LA219X promoted lincomycin production by 17.8%, and SLCG_2185 being co-overexpressed with SLCG_Lrp in LA219X increased lincomycin production by 28.1% compared to LA219X. Therefore, this investigation not only provides a direction for further investigations regarding the regulation mechanism of SLCG_Lrp, but also provides a basis for guiding the further improvement of lincomycin levels. [ABSTRACT FROM AUTHOR]

The regulatory mechanism of lincomycin biosynthesis remains largely unknown, although lincomycin and its derivatives have been of great application in pharmaceutical industry. As a global regulator, BldD is widespread in Streptomyces , and functions as an on-off switch to regulate the transition from morphological differentiation to secondary metabolism, inspiring us to explore scarcely regulatory realm of lincomycin biosynthesis. In this work, deletion of bldD gene (SLCG_1664) in Streptomyces lincolnensis blocked the sporulation and nearly abolished lincomycin production, while the morphological phenotype and lincomycin production were restored when introducing a functional bldD gene into the Δ bldD mutant. S. lincolnensis BldD (BldD SL) was validated to bind to upstream regions of lincomycin biosynthetic structural genes lmbA , lmbC-lmbD , lmbE , lmbV-lmbW , resistant genes lmrA , lmrB , lmrC , and regulatory gene lmbU. Disruption of bldD significantly decreased the transcription of genes in lincomycin biosynthetic cluster, thus resulting in the sharply loss of lincomycin production. These findings indicate that BldD SL , similar to Saccharopolyspora erythraea BldD (BldD SE), directly regulates the biosynthesis of lincomycin. What's more, we discovered that BldD SE could bind to upstream regions of lmbA , lmbV - lmbW , lmrA and lmrC. Corresponding to this, S. lincolnensis BldD can bind to upstream region of eryAI - eryBIV , revealing an interactional regulation of the two BldDs. In summary, our data indicated that the developmental regulator BldD played a vital role in directly regulating the biosynthesis of lincomycin, and expanded the knowledge on lincomycin biosynthetic regulation in S. lincolnensis. • BldD SL affects morphological differentiation and cell growth of S. lincolnensis. • BldD SL positively regulates lincomycin production. • BldD SL directly regulates lincomycin biosynthesis by binding to most gene promoters in lincomycin biosynthesis cluster. • BldD SL presents functional inter-regulation with BldD SE from S. erythraea. [ABSTRACT FROM AUTHOR]