title: Three subfamilies of pheromone and receptor genes generate multiple B mating specificities in the mushroom Coprinus cinereus.
abstract: The B mating type locus of the basidiomycete Coprinus cinereus encodes a large family of lipopeptide pheromones and their seven transmembrane domain receptors. Here we show that the B42 locus, like the previously described B6 locus, derives its unique specificity from nine multiallelic genes that are organized into three subgroups each comprising a receptor and two pheromone genes. We show that the three genes within each group are kept together as a functional unit by being embedded in an allele-specific DNA sequence. Using a combination of sequence analysis, Southern blotting, and DNA-mediated transformation with cloned genes, we demonstrate that different B loci may share alleles of one or two groups of genes. This is consistent with the prediction that the three subgroups of genes are functionally redundant and that it is the different combinations of their alleles that generate the multiple B mating specificities found in nature. The B42 locus was found to contain an additional gene, mfs1, that encodes a putative multidrug transporter belonging to the major facilitator family. In strains with other B mating specificities, this gene, whose functional significance was not established, lies in a region of shared homology flanking the B locus.
authors.affiliation: Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.
authors.forename: J R
authors.initials: JR
authors.lastname: Halsall
authors.forename: M J
authors.initials: MJ
authors.lastname: Milner
authors.forename: L A
authors.initials: LA
authors.lastname: Casselton
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D003302:Coprinus / Q000235:genetics*; D004271:DNA, Fungal; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D008969:Molecular Sequence Data; D010675:Pheromones / Q000235:genetics*; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014157:Transcription Factors
chemical_list: D004271:DNA, Fungal; D010675:Pheromones; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide; D014157:Transcription Factors