Most clinical antibiotics are derived from actinomycete natural products discovered at least 60 years ago. However, the repeated rediscovery of known compounds led the pharmaceutical industry to largely discard microbial natural products (NPs) as a source of new chemical diversity. Recent advances in genome sequencing have revealed that these organisms have the potential to make many more NPs than previously thought. Approaches to unlock NP biosynthesis by genetic manipulation of strains, by the application of chemical genetics, or by microbial cocultivation have resulted in the identification of new antibacterial compounds. Concomitantly, intensive exploration of coevolved ecological niches, such as insect-microbe defensive symbioses, has revealed these to be a rich source of chemical novelty. Here, we report the new lanthipeptide antibiotic kyamicin, which was generated through the activation of a cryptic biosynthetic gene cluster identified by genome mining Saccharopolyspora species found in the obligate domatium-dwelling ant Tetraponera penzigi of the ant plant Vachellia drepanolobium. Transcriptional activation of this silent gene cluster was achieved by ectopic expression of a pathway-specific activator under the control of a constitutive promoter. Subsequently, a heterologous production platform was developed which enabled the purification of kyamicin for structural characterization and bioactivity determination. This strategy was also successful for the production of lantibiotics from other genera, paving the way for a synthetic heterologous expression platform for the discovery of lanthipeptides that are not detected under laboratory conditions or that are new to nature.

IMPORTANCE The discovery of novel antibiotics to tackle the growing threat of antimicrobial resistance is impeded by difficulties in accessing the full biosynthetic potential of microorganisms. The development of new tools to unlock the biosynthesis of cryptic bacterial natural products will greatly increase the repertoire of natural product scaffolds. Here, we report a strategy for the ectopic expression of pathway-specific positive regulators that can be rapidly applied to activate the biosynthesis of cryptic lanthipeptide biosynthetic gene clusters. This allowed the discovery of a new lanthipeptide antibiotic directly from the native host and via heterologous expression.

大多数临床抗生素均源自至少60年前发现的放线菌天然产物。但是，重复发现已知化合物导致制药业大量丢弃微生物天然产物（NPs）作为新化学多样性的来源。基因组测序的最新进展表明，这些生物有潜力制造比以前想象的更多的NP。通过菌株的遗传操作，化学遗传学的应用或微生物共培养来解锁NP生物合成的方法导致了新抗菌化合物的鉴定。随之而来的是，深入探索共同进化的生态位，例如昆虫-微生物防御共生体，发现它们是化学新颖性的丰富来源。这里，糖多品种的专domatium栖蚁发现Tetraponera penzigi蚂蚁工厂Vachellia drepanolobium。该沉默基因簇的转录激活是通过在组成型启动子的控制下异位表达途径特异性激活子来实现的。随后，开发了异源生产平台，该平台能够纯化kyamicin，以用于结构表征和生物活性测定。该策略也成功地用于生产其他属的羊毛硫抗生素，为合成异源表达平台铺平了道路，该平台用于发现在实验室条件下未检测到或对自然界不新鲜的羊毛肽。

重要信息由于难以获得微生物的全部生物合成潜能，阻碍了新型抗生素的发现，以解决日益增长的抗微生物药物耐药性威胁。解锁隐秘细菌天然产物生物合成的新工具的开发将大大增加天然产物支架的功能。在这里，我们报告了一种途径特异性正调控因子的异位表达策略，该策略可以快速应用于激活隐性肽多肽生物合成基因簇的生物合成。这允许直接从天然宿主并通过异源表达发现新的肽肽抗生素。