The chromosomal region containing pab-1, mip, and the A mating type locus of the secondarily homothallic homobasidiomycete Coprinus bilanatus

In this paper we describe the cloning of the DNA region containing the A1 m ating type genes of the secondarily homothallic mushroom Coprinus bilanatus and compare its organization to that of heterothallic homobasidiomycetes. As in other species, the C. bilanatus A factor contains several different g enes that encode two different types of homeodomain transcription factor (H D1 and HD2); and some of these genes are active in the heterologous host C. cinereus. The HD1 and HD genes are distributed over two closely linked sub loci, A alpha and AP. A gene coding for a mitochondrial intermediate peptid ase (mip) directly flanks the A alpha sublocus. The pab-1 gene, required fo r para-aminobenzoic acid synthesis, is found 39 kb upstream of mip. The str uctural arrangement of this chromosomal region closely resembles the hetero thallic C. cinereus. In contrast, the A alpha and A beta subloci of Schizop hyllum commune are further separated, with pab-1 located between the two su bloci, suggesting that a translocation event evolution. may have occurred d uring evolution.