Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin, 300350, China.
State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096, China.
Microb Cell Fact. 2020 Feb 12;19(1):30. doi: 10.1186/s12934-020-01298-0.
Lincomycin, produced by Streptomyces lincolnensis, is a lincosamide antibiotic and widely used for the treatment of the infective diseases caused by Gram-positive bacteria. The mechanisms of lincomycin biosynthesis have been deeply explored in recent years. However, the regulatory effects of LmbU that is a transcriptional regulator in lincomycin biosynthetic (lmb) gene cluster have not been fully addressed.
LmbU was used to search for homologous LmbU (LmbU-like) proteins in the genomes of actinobacteria, and the results showed that LmbU-like proteins are highly distributed regulators in the biosynthetic gene clusters (BGCs) of secondary metabolites or/and out of the BGCs in actinomycetes. The overexpression, inactivation and complementation of the lmbU gene indicated that LmbU positively controls lincomycin biosynthesis in S. lincolnensis. Comparative transcriptomic analysis further revealed that LmbU activates the 28 lmb genes at whole lmb cluster manner. Furthermore, LmbU represses the transcription of the non-lmb gene hpdA in the biosynthesis of L-tyrosine, the precursor of lincomycin. LmbU up-regulates nineteen non-lmb genes, which would be involved in multi-drug flux to self-resistance, nitrate and sugar transmembrane transport and utilization, and redox metabolisms.
LmbU is a significant pleiotropic transcriptional regulator in lincomycin biosynthesis by entirely activating the lmb cluster and regulating the non-lmb genes in Streptomyces lincolnensis. Our results first revealed the pleiotropic regulatory function of LmbU, and shed new light on the transcriptional effects of LmbU-like family proteins on antibiotic biosynthesis in actinomycetes.
林可霉素由林肯链霉菌产生，是一种林可酰胺类抗生素，广泛用于治疗革兰氏阳性菌引起的感染性疾病。近年来，林可霉素生物合成的机制已经得到了深入的研究。然而，在林可霉素生物合成（lmb）基因簇中作为转录调节剂的 LmbU 的调节作用尚未得到充分解决。
利用 LmbU 搜索放线菌基因组中的同源 LmbU（LmbU-like）蛋白，结果表明 LmbU-like 蛋白是放线菌中次级代谢物生物合成基因簇（BGCs）内和 BGC 外高度分布的调控因子。lmbU 基因的过表达、失活和互补表明 LmbU 正向调控林肯链霉菌中的林可霉素生物合成。比较转录组分析进一步表明，LmbU 以全 lmb 簇的方式激活 28 个 lmb 基因。此外，LmbU 抑制 L-酪氨酸生物合成中非 lmb 基因 hpdA 的转录，L-酪氨酸是林可霉素的前体。LmbU 上调 19 个非 lmb 基因，这些基因可能参与多药通量以实现自身抗性、硝酸盐和糖的跨膜运输和利用以及氧化还原代谢。
LmbU 是林肯链霉菌中林可霉素生物合成的重要多功能转录调控因子，通过完全激活 lmb 簇和调节非 lmb 基因来实现。我们的研究结果首次揭示了 LmbU 的多功能调节功能，并为 LmbU 样家族蛋白对放线菌中抗生素生物合成的转录影响提供了新的见解。
