Microbiology Section, Department of Molecular Biology, University of León, León 24071, Spain.
J Ind Microbiol Biotechnol. 2021 Dec 23;48(9-10). doi: 10.1093/jimb/kuab072.
The Streptomyces clavuligerus genome consists in a linear chromosome of about 6.7 Mb and four plasmids (pSCL1 to pSCL4), the latter one of 1.8 Mb. Deletion of pSCL4, results in viable mutants with high instability in the chromosome arms, which may lead to chromosome circularisation. Transcriptomic and proteomic studies comparing different mutants with the wild-type strain improved our knowledge on the biosynthesis and regulation of clavulanic acid, cephamycin C and holomycin. Additional knowledge has been obtained on the SARP-type CcaR activator and the network of connections with other regulators (Brp, AreB, AdpA, BldG, RelA) controlling ccaR expression. The transcriptional pattern of the cephamycin and clavulanic acid clusters is supported by the binding of CcaR to different promoters and confirmed that ClaR is a CcaR-dependent activator that controls the late steps of clavulanic biosynthesis. Metabolomic studies allowed the detection of new metabolites produced by S. clavuligerus such as naringenin, desferroxamines, several N-acyl tunicamycins, the terpenes carveol and cuminyl alcohol or bafilomycin J. Heterologous expression of S. clavuligerus terpene synthases resulted in the formation of no less than 15 different terpenes, although none of them was detected in S. clavuligerus culture broth. In summary, application of the Omic tools results in a better understanding of the molecular biology of S. clavuligerus, that allows the use of this strain as an industrial actinobacterial platform and helps to improve CA production.
棒状链霉菌的基因组由一条约 6.7 Mb 的线性染色体和四个质粒（pSCL1 到 pSCL4）组成，其中后者为 1.8 Mb。缺失 pSCL4 会导致染色体臂高不稳定的活突变体，这可能导致染色体环化。比较不同突变体与野生型菌株的转录组学和蛋白质组学研究，提高了我们对棒状链霉菌克拉维酸、头孢菌素 C 和霍洛霉素生物合成和调控的认识。此外，还获得了关于 SARP 型 CcaR 激活剂和与其他调节剂（Brp、AreB、AdpA、BldG、RelA）的网络连接的知识，这些调节剂控制 ccaR 的表达。头孢菌素和克拉维酸簇的转录模式得到了 CcaR 与不同启动子结合的支持，并证实 ClaR 是一种依赖 CcaR 的激活剂，它控制克拉维酸生物合成的后期步骤。代谢组学研究允许检测到棒状链霉菌产生的新代谢物，如柚皮素、去铁胺、几种 N-酰基曲霉菌、萜品醇和枯茗醇或巴弗洛霉素 J。棒状链霉菌萜烯合酶的异源表达导致形成了不少于 15 种不同的萜烯，尽管在棒状链霉菌培养物中没有检测到它们。总之，应用组学工具可以更好地理解棒状链霉菌的分子生物学，这使得该菌株可以作为一种工业放线菌平台，并有助于提高 CA 的产量。
