The main focus of our research is the functional genomics of the biosynthesis of prenylated indole derivatives in Ascomycetes as well as the production of natural and „unnatural“ secondary metabolites by in vitro chemoenzymatic and in vivo synthetic approaches. Prenylated indole derivatives are a large group of natural products with diverse structures and interesting biological activities. These compounds are derived from dimethylallyl diphosphate and tryptophan, which often forms cyclic dipeptides with a second amino acid. Non-ribosomal peptide synthetases (NRPSs) and prenyltransferases of the dimethylallyltryptophansynthase (DMATS)-superfamily are two key enzyme groups in the biosynthesis of these substances. NRPSs are responsible for the formation of the dipeptide backbone, whilst prenyltransferases act as modification enzymes for decoration and therefore play an important role in structure diversity and biological activity. Molecular, biochemical, and synthetic biological investigations are carried out in our laboratory for both enzyme groups.
Within the framework of SYNMIKRO, we are interested in the functions of fungal non-ribosomal peptide synthetases (NRPSs) and their potential use for the production of hybrid natural products by combination of different NRPS genes with other biosynthetic genes from different gene clusters. Bimodular NRPS genes are the first candidate genes of interest. They are responsible for the biosynthesis of linear or cyclic dipeptides in fungi and can be identified in genome sequences by bioinformatic approaches. After PCR amplification of the gene of interest from genomic DNA and cloning of the obtained PCR product in an adequate expression vector, the gene expression will be carried out in Aspergillus nidulans or/and Aspergillus niger. Isolation and structure elucidation of the accumulated secondary metabolites from the transformants provide direct information on the function of the gene of interest.
In order to get enzymes with novel features regarding substrates and products, domains of different NRPS genes should be recombined. Such recombinant genes can be easily created by fusion PCR and used for combination with other genes mentioned above.