Zhang Yue, Lin Chun-Yan, Li Xiao-Mei, Tang Zheng-Kun, Qiao Jianjun, Zhao Guang-Rong
Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300072, China.
Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, University, Tianjin, 300072, China.
J Ind Microbiol Biotechnol. 2016 Dec;43(12):1681-1692. doi: 10.1007/s10295-016-1845-4. Epub 2016 Oct 8.
The polyether ionophore antibiotic monensin is produced by Streptomyces cinnamonensis and is used as a coccidiostat for chickens and growth-promoting agent for cattle. Monensin biosynthetic gene cluster has been cloned and partially characterized. The GntR-family transcription factor DasR regulates antibiotic production and morphological development in Streptomyces coelicolor and Saccharopolyspora erythraea. In this study, we identified and characterized the two-level regulatory cascade of DasR to monensin production in S. cinnamonensis. Forward and reverse genetics by overexpression and antisense RNA silence of dasR revealed that DasR positively controls monensin production under nutrient-rich condition. Electrophoresis mobility shift assay (EMSA) showed that DasR protein specifically binds to the promoter regions of both pathway-specific regulatory gene monRII and biosynthetic genes monAIX, monE and monT. Semi-quantitative RT-PCR further confirmed that DasR upregulates the transcriptional levels of these genes during monensin fermentation. Subsequently, co-overexpressed dasR with pathway-specific regulatory genes monRI, monRII or monH greatly improved monensin production.
聚醚离子载体抗生素莫能菌素由肉桂链霉菌产生，用作鸡的抗球虫药和牛的生长促进剂。莫能菌素生物合成基因簇已被克隆并部分表征。GntR家族转录因子DasR调节天蓝色链霉菌和红色糖多孢菌中的抗生素生产和形态发育。在本研究中，我们鉴定并表征了DasR对肉桂链霉菌中莫能菌素生产的两级调控级联。通过dasR的过表达和反义RNA沉默进行正向和反向遗传学研究表明，DasR在营养丰富的条件下正向控制莫能菌素的生产。电泳迁移率变动分析（EMSA）表明，DasR蛋白特异性结合途径特异性调控基因monRII以及生物合成基因monAIX、monE和monT的启动子区域。半定量RT-PCR进一步证实，DasR在莫能菌素发酵过程中上调这些基因的转录水平。随后，将dasR与途径特异性调控基因monRI、monRII或monH共过表达可大大提高莫能菌素的产量。
