This report highlights the first biochemical characterization of a multi-domain biosynthetic enzyme for basidiomycete secondary metabolism: the tri-domain enzyme atromentin synthetase AtrA, from Tapinella panuoides, which adenylates and dimerizes 4-hydroxyphenylpyruvic acid into atromentin. Also, the l-tyrosine:2-oxoglutarate aminotransferase AtrD, which provides the substrate for this dimerization step, has been characterized. AtrA and AtrD expand the shikimic acid pathway from l-tyrosine to atromentin, the central terphenylquinone intermediate for a prominent and widely occurring class of basidiomycete pigments, among them various pharmaceutically relevant compounds. The genes atrA and atrD were cloned and found to be clustered within one genetic locus. Given the broad distribution of atromentin-derived compounds among homobasidiomycetes we expect our system represents a widely applicable model.