Sunday, August 10, 2008
P95

A Genetic and Biochemical Model for Secondary Metabolism In Wood-Degrading Basidiomycetes

Patrick M. Schneider, Pharmazeutische Biologie und Biotechnologie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-str. 17, Freiburg, Germany and Dirk Hoffmeister, Plant Pathology, University of Minnesota, 1991 Upper Buford Circle, Saint Paul, MN 55108.

 The biochemical and genetic basis how basidiomycetes synthesize bioactive natural products has largely remained elusive, which is why we searched for a representative compound and species to investigate their natural product assembly biochemically. Previous feeding experiments suggest that basidiomycete terphenylquinones and the asterriquinones, produced by Aspergilli and various Ascomycetes, share a common biosynthetic principle, which is deamination and dimerization of two aromatic amino acids. Recently, the first genetic locus for an asterriquinone, the clustered terrequinone genes tdiAE, was identified during a genome-wide screen in Aspergillus nidulans. With this data available, we screened a genomic cosmid library of the basidiomycete brown-rotter Tapinella panuoides for orthologs and identified candidate genes for terphenylquinone biosynthesis. Their function was confirmed biochemically: atrA codes for a nonribosomal peptide synthetase-like tri-domain enzyme, and atrD for a transaminase.