Exogenous 1,4‐butyrolactone stimulates A‐factor‐like cascade and validamycin biosynthesis in Streptomyces hygroscopicus 5008
Exogenous 1,4‐butyrolactone stimulates A‐factor‐like cascade and validamycin biosynthesis in Streptomyces hygroscopicus 5008
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DOI：
10.1002/bit.24965
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发表时间：
2013-11
影响因子：
3.8
通讯作者：
Gao-Yi Tan;Linquan Bai;J. Zhong
中科院分区：
文献类型：
--
作者：
Gao-Yi Tan;Linquan Bai;J. Zhong
丁内酯类化合物(γ-Butyoloactones，GBL)，如A-因子，是链霉菌产生的一类信号分子，具有调节次生代谢的作用。然而，它们的产量通常很小，这阻碍了它们的结构阐明和在抗生素过量生产中的应用。本工作将1，4-丁内酯(1，4-BL)作为一种易得、廉价的GBLS类似物应用于吸水链霉菌5008产生的重要抗真菌抗生素--有效霉素A(Validamcin A，Val-A)的发酵。在摇瓶和生物反应器中，添加1，4-BL可使Val-A的产量提高30%。AdpA同源基因(adpA-H)和valA生物合成基因的转录水平显著提高。在吸水链霉菌5008基因组中鉴定的3个A因子受体同源基因中，经基因断裂和圆二色谱分析证明shbR3与1，4-BL的诱导活性有关，EMSA分析表明shbR3能与adpA-H的启动子区域结合。此外，adpA-H突变还导致Val-A生物合成基因转录和Val-A产量下降。在EMSA分析中，AdpA-H可以直接结合到Val-A基因簇的启动子区域。此外，1，4-BL的添加也提高了高产菌株TL01的Val-A产量。结果表明，1，4-BL能刺激类A因子级联反应，进而提高吸湿链霉菌5008中Val-A的产量。生物技术。比昂斯。2013；110：2984-2993。©2013 Wiley期刊，Inc.
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. Biotechnol. Bioeng. 2013;110: 2984–2993. © 2013 Wiley Periodicals, Inc.