Deciphering the substrate specificity code of basidiomycete peptide synthetases

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The number of fully sequenced and publically accessible basidiomycete genomes is increasing at a fast pace. It has become evident that many species within this diverse group of fungi harbor the genetic material for a structurally diverse secondary metabolism to biosynthesize small molecule natural products, the majority of which has not been identified and chemically characterized yet. This research project serves to close this gap between genomics and natural product chemistry by enabling the prediction of natural product (partial) structures from genomic sequence data. The objective is to identify and characterize secondary metabolomes in a more straightforward way. Hence, discovery of new bioactive compounds which may serve as pharmaceutically relevant drug leads is facilitated.This work combines biochemistry, bioinformatics, and natural product chemistry, and focuses on nonribosomal peptide synthetases (NRPSs) and related proteins. These are multidomain enzymes which catalyze the assembly of complex natural products from generic substrates, such as amino acids, keto acids, and others. The substrate specificity and, thus, structural features of the product, is governed by ten positions within the primary NRPS amino acid sequence, which are collectively referred to as NRPS-code. This code is virtually unknown for the basidiomycetes.In vitro biochemical characterization of peptide synthetases of select Basidiomycota species will profile the substrate specificities and establish an NRPS-code for the individual substrates. This approach is supported by modeling the respective enzymes/domains in silico. Chemical investigations with the chosen fungal species, primarily feeding of labeled substrates, and natural product isolation and structure elucidation, will verify biochemical results.