Developmental regulator BldD directly regulates lincomycin biosynthesis in Streptomyces lincolnensis.

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 ΔbldD mutant. S. lincolnensis BldD (BldD) 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, similar to Saccharopolyspora erythraea BldD (BldD), directly regulates the biosynthesis of lincomycin. What's more, we discovered that BldD 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.