Untersuchung der Substratspezifitäten von Adenylierungsdomänen aus Ascomyceten und Basidiomyceten
The structurally diverse nonribosomal peptides build up an important class of natural products. They are synthesized by large, modular, multifunctional nonribosomal peptide synthetases in an assembly line fashion. This study was focused on the characterization of adenylation domains of noncanonical NRPSs of asco- and basidiomycetes. The biochemical characterization of adenylate forming reductases of the basidiomycetes Serpula lacrymans and Heterobasidion annosum underline the wide range of substrates incorporated by fungal NRPSs and the structurally diversity of these enzyme class. For the representatives NPS9 and NPS11 of S. lacrymans we identified L-threonine and benzoic acid as preferred substrates. NPS10 of H. annosum activates phenylpyruvic acid. The iterative adenylation domain of the siderophore synthetase CsNPS2 preferred the nonproteinogenic amino acid N5-acetyl-N5-hydroxy-L-ornithine (L-AHO). A chelating trimer of L-AHO could be detected in vitro. This class VI fungal siderophore synthetase is highly conserved across various basidiomycetes but CsNPS2 is the first biochemically characterized one. Next, we analyzed the noncanonical NRPS FsqF, which catalyzes the first step during the biosynthesis of fumisoquins. FsqF is required for carbon-carbon bond formation between L-serine and L-tyrosine derived monomers.