Project description:Background: Fungi are important sources for bioactive compounds that find their applications in many important sectors like in the pharma-, food- or agricultural industries. In an environmental monitoring project for fungi involved in soil nitrogen cycling we also isolated Cephalotrichum gorgonifer (strain NG_p51). In the course of strain characterization work we found that this strain is able to produce high amounts of rasfonin, a polyketide inducing autophagy, apoptosis, necroptosis in human cell lines and shows anti-tumor activity in RAS-dependent cancer cells. Results: In order to elucidate the biosynthetic pathway of rasfonin, the strain was genome sequenced, annotated, submitted to transcriptome analysis and genetic transformation was established. Biosynthetic gene cluster (BGC) prediction revealed the existence of 22 BGCs of which the majority was not expressed under our experimental conditions. In silico prediction revealed two BGCs with a suite of enzymes possibly involved in rasfonin biosynthesis. Experimental verification by gene-knock out of the key enzyme genes showed that one of the predicted BGCs is s indeed responsible for rasfonin biosynthesis. Conclusions: The results of this study lay the ground for molecular biology focused research in Cephalotrichum gorgonifer. Furthermore, strain engineering and heterologous expression of the rasfonin BGC is now possible which facilitates the construction of high producing strains or the synthesis of rasfonin derivates for diverse applications.
Project description:Actinobacteria produce about two-thirds of all naturally derived antibiotics currently in clinical use. Kitasatospora aureofaciens Tü117 is a species of Actinobacteria and produces α-lipomycin. We report the complete genome sequence of K. aureofaciens, composed of a single linear chromosome of 8,717,539 Mbp with a G + C content of 72.0%.
Project description:Filamentous marine cyanobacteria are extraordinarily rich sources of structurally novel, biomedically relevant natural products. To understand their biosynthetic origins as well as produce increased supplies and analog molecules, access to the clustered biosynthetic genes that encode for the assembly enzymes is necessary. Complicating these efforts is the universal presence of heterotrophic bacteria in the cell wall and sheath material of cyanobacteria obtained from the environment and those grown in uni-cyanobacterial culture. Moreover, the high similarity in genetic elements across disparate secondary metabolite biosynthetic pathways renders imprecise current gene cluster targeting strategies and contributes sequence complexity resulting in partial genome coverage. Thus, it was necessary to use a dual-method approach of single-cell genomic sequencing based on multiple displacement amplification (MDA) and metagenomic library screening. Here, we report the identification of the putative apratoxin. A biosynthetic gene cluster, a potent cancer cell cytotoxin with promise for medicinal applications. The roughly 58 kb biosynthetic gene cluster is composed of 12 open reading frames and has a type I modular mixed polyketide synthase/nonribosomal peptide synthetase (PKS/NRPS) organization and features loading and off-loading domain architecture never previously described. Moreover, this work represents the first successful isolation of a complete biosynthetic gene cluster from Lyngbya bouillonii, a tropical marine cyanobacterium renowned for its production of diverse bioactive secondary metabolites.