Agaricus bisporus and Coprinus bilanatus TRP2 genes are tri-functional with conserved intron and domain organisations

Cloned homobasidiomycete TRP2 genes for Agaricus bisporus and Coprinus bilanatus were sequence-characterised. Both genes encode tri-functional proteins with activity domains for glutamine amidotransferase (GAT; G domain), indole glycerol phosphate synthase (InGP; C domain) and phosphoribosyl anthranilate isomerase (F domain). A conserved intron disrupts the GAT-coding sequence in both genes. Consensus amino acid (aa) signatures were identified for GAT and InGP, but in the latter 15-aa signature, one residue did not fit the previously defined consensus. Protein architecture and parsimony analysis with analogous proteins indicate domain organisation (NH2-G-C-F-COOH) was as for other filamentous fungi. The data do not support earlier suggestions that the three activity domains are detached in A. bisporus.