Transcription factor NecR promotes the synthesis of neomycin in Streptomyces fradiae

Abstract

Neomycin, a crucial aminoglycoside antibiotic, is primarily biosynthesized by Streptomyces fradiae through fermentation. Its widespread applications encompass disease management in crops, treatment of bacterial infections in respiratory and gastrointestinal tracts, among other domains, leading to substantial market demand. Increasing evidence underscores the pivotal role of transcription factors in microbial metabolic regulation, orchestrating the coordinated expression of multiple genes in specific pathways. This orchestration holds the potential to enhance engineered microbial strains, thereby facilitating the precise and efficient synthesis of neomycin. Leveraging transcriptomic analyses of the wild-type strain SF-1 and the mutation-derived high-yield strain SF-2, this study identified significant variations in the expression levels of seven transcription factors. By constructing recombinant strains overexpressing these seven transcription factors, the optimal factor NecR, influencing neomycin production, was pinpointed. Further, promoter optimization was employed to augment neomycin synthesis. Under shaken flask cultivation conditions, the titer of neomycin B reached 11,546 U/mL, marking a 23% enhancement over the mutation-derived high-yield strain SF-2. The in vivo fluorescence reporter gene characterization using EMSA binding revealed that NecR can bind to the promoter region of neoS, thereby enhancing the transcriptional levels of neoS, subsequently promoting neomycin synthesis. This investigation not only furnishes pivotal insights for the construction of high-yield neomycin-producing strains but also elucidates the central role of transcription factors in microbial metabolic regulation. This revelation is poised to offer novel avenues and strategies in the realm of microbial metabolic engineering, holding promise for significant breakthroughs in antibiotic production and other bioproduct synthesis domains.

Keywords

S. fradiae / Neomycin / Transcriptomic analysis / Transcription factor / Promoter optimization

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Funding

National Natural Science Foundations of China(31471615)

Scientific Research Start-up Fund for Introduced Talents of Anhui Polytechnic University(2022YOO068)

Natural Science Research Project of Colleges and Universities in Anhui Province(2022AH050971)

Huimin Technology Research and Development Projects of Ningbo Municipality(2023yf096)