title: Exogenous 1,4-butyrolactone stimulates A-factor-like cascade and validamycin biosynthesis in Streptomyces hygroscopicus 5008.
abstract: γ-Butyrolactones (GBLs), such as A-factor, are one type of signaling molecules produced by Streptomyces species and have been reported to regulate secondary metabolism. However, they are usually produced in very small amount, which has hindered their structural elucidation and application for antibiotic overproduction. In this work, 1,4-butyrolactone (1,4-BL), as an easily accessible and cheap analogue of GBLs, was applied to the fermentation of validamycin A (VAL-A), an important antifungal antibiotic produced by Streptomyces hygroscopicus 5008. The addition of 1,4-BL enhanced VAL-A production by 30% in both shaking flasks and bioreactors. The transcriptional levels of the adpA homologue (adpA-H) and VAL-A biosynthetic genes were significantly increased. Among the three A-factor receptor homologous genes identified in the genome of S. hygroscopicus 5008, shbR3 was proved to be responsible for the inducing activity of 1,4-BL by gene disruption and circular dichroism analysis, and ShbR3 could bind to the promoter region of adpA-H as indicated by EMSA analysis. Furthermore, the mutation of adpA-H abolished the transcription of VAL-A biosynthetic genes and VAL-A productivity. In EMSA analysis, AdpA-H could directly bind to the promoter regions of VAL-A gene cluster. Moreover, addition of the 1,4-BL also improved the VAL-A production in a high-yielding strain TL01. The results showed that 1,4-BL could stimulate A-factor-like cascade and subsequently enhance VAL-A production in S. hygroscopicus 5008.
authors.affiliation: State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong-chuan Road, Shanghai, 200240, China.
authors.forename: Gao-Yi
authors.initials: GY
authors.lastname: Tan
authors.forename: Linquan
authors.initials: L
authors.lastname: Bai
authors.forename: Jian-Jiang
authors.initials: JJ
authors.lastname: Zhong
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism*; D000935:Antifungal Agents / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000235:genetics; D002942:Circular Dichroism; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005285:Fermentation; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D007294:Inositol / Q000031:analogs & derivatives* / Q000096:biosynthesis; D011485:Protein Binding; D013302:Streptomyces / Q000187:drug effects* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D004269:DNA, Bacterial; D014157:Transcription Factors; D007294:Inositol; C003749:validamycins; D015107:4-Butyrolactone
keywords: Streptomyces; fermentation; regulation; validamycin; γ-butyrolactone