Kormanec Jan, Novakova Renata, Csolleiova Dominika, Feckova Lubomira, Rezuchova Bronislava, Sevcikova Beatrica, Homerova Dagmar
Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 845 51, Bratislava, Slovak Republic.
Appl Microbiol Biotechnol. 2020 Sep;104(18):7701-7721. doi: 10.1007/s00253-020-10782-x. Epub 2020 Jul 20.
The aureolic acid-type polyketide mithramycin (MTM) has a remarkable cytotoxicity against a variety of human tumors and has been used for the treatment of several types of cancer, including chronic and acute myeloid leukemia, testicular carcinoma, hypercalcemia, and Paget's disease. However, its clinical use is quite limited due to its toxicity. Recently, interest in MTM has been renewed after its identification as a top candidate for the inhibition of the aberrant fusion transcription factor EWS-FLI1, associated with malignant transformation and progression of Ewing sarcoma tumor family. The mechanism of MTM inhibition involves its reversible non-intercalative interaction with GC-rich DNA regions. As a result of this binding, MTM blocks binding of transcription factors (such as Sp1) to their GC-rich promoters and inhibits transcription of several proto-oncogenes and thus suppresses various types of cancer. Knowledge of the biosynthesis of MTM and its gene cluster has enabled genetic modifications of the gene cluster and combinatorial biosynthesis to produce new modified MTM molecules ("mithralogues") with improved efficacy and lower toxicity, which has also renewed interest in the clinical development of MTM. However, production yields of MTM and its analogues are low in the natural production strains. Recent developments in genetic engineering approaches have made it possible to increase MTM production through more rational strategies based on genetic manipulations and heterologous expression in optimized chassis. Recent construction of various genetically modified strains of Streptomyces lividans has shown their use for efficient heterologous production of various biologically active secondary metabolites including MTM. KEY POINTS: • Discovery a novel bifunctional glycosyl hydrolase from uncultured microorganism. • Heterologous production of MTM in engineered S. lividans strains is efficient.
金霉素型聚酮化合物光神霉素（MTM）对多种人类肿瘤具有显著的细胞毒性，已被用于治疗多种类型的癌症，包括慢性和急性髓性白血病、睾丸癌、高钙血症和佩吉特病。然而，由于其毒性，其临床应用相当有限。最近，在MTM被确定为抑制异常融合转录因子EWS-FLI1的顶级候选药物后，人们对它的兴趣再次燃起，该转录因子与尤因肉瘤肿瘤家族的恶性转化和进展有关。MTM的抑制机制涉及其与富含GC的DNA区域的可逆非嵌入相互作用。这种结合导致MTM阻断转录因子（如Sp1）与其富含GC的启动子的结合，并抑制几种原癌基因的转录，从而抑制各种类型的癌症。对MTM及其基因簇生物合成的了解使得对基因簇进行基因改造和组合生物合成成为可能，从而产生具有更高疗效和更低毒性的新型修饰MTM分子（“mithralogues”），这也重新激发了人们对MTM临床开发的兴趣。然而，MTM及其类似物在天然生产菌株中的产量很低。基因工程方法的最新进展使得通过基于基因操作和在优化底盘中的异源表达的更合理策略来提高MTM产量成为可能。最近构建的各种产紫青霉菌基因改造菌株已显示出它们可用于高效异源生产包括MTM在内的各种生物活性次级代谢产物。要点：• 从未培养的微生物中发现一种新型双功能糖基水解酶。• 在工程改造的产紫青霉菌株中高效异源生产MTM。
