An expression system for the functional analysis of pheromone genes in the tetrapolar basidiomycete Schizophyllum commune.

The investigation of putative pheromone genes of basidiomycetes has been difficult since the small open reading frames are essentially annotated on the basis of a C-terminal farnesylation signal. In order to identify the functional reading frame, expression of small DNA fragments in the fungus is necessary. The expression system developed in the presented paper allows fusion to the promoter of the tef1 gene encoding the constitutively and highly expressed translation elongation factor EF1alpha. This system has been shown to be functional using an easily selectable gene, ura1. The application to identification of functional pheromone genes has been shown with the newly detected bap2(4) gene. The Bap2(4) pheromone is the first Balpha pheromone gene activating only a single receptor specificity.