Crossing the boundary between the Balpha and the Bbeta mating-type loci in Schizophyllum commune

In this study, genes of the Schizophyllum commune Balpha and Bbeta mating-type loci are shown to be within a few kilobases of each other. The region between the nearest Balpha and Bbeta genes contains many short direct repeats. Predicted amino acid sequences and activity spectra of three pheromones encoded in the Balpha3 mating-type specificity are presented along with a re-evaluation of pheromone activity of many previously reported S. commune lipopeptide pheromones. This analysis showed that S. commune pheromones belong to five subtypes. Several pheromones activate both a Bbeta receptor and a Balpha receptor, a phenomenon previously unrecognized. Clues from mating tests and DNA hybridization led to the cloning of bar8, the gene encoding the Balpha8 pheromone receptor, Bar8. Bar8 is similar in sequence to Bbr1, the Bbeta1 pheromone receptor, and functionally identical to it. These data begin to elucidate the enigmatic recombination patterns previously encountered at the B mating-type complex.