title: Asymmetry in sexual pheromones is not required for ascomycete mating.
abstract: BACKGROUND
  We investigated the determinants of sexual identity in the budding yeast Saccharomyces cerevisiae. The higher fungi are divided into the ascomycetes and the basidiomycetes. Most ascomycetes have two mating types: one (called α in yeasts and MAT1-1 in filamentous fungi) produces a small, unmodified, peptide pheromone, and the other (a in yeasts and MAT1-2 in filamentous fungi) produces a peptide pheromone conjugated to a C-terminal farnesyl group that makes it very hydrophobic. In the basidiomycetes, all pheromones are lipid-modified, and this difference is a distinguishing feature between the phyla. We asked whether the asymmetry in pheromone modification is required for successful mating in ascomycetes.
  
  
  RESULTS
  We cloned receptor and pheromone genes from a filamentous ascomycete and a basidiomycete and expressed these in the budding yeast, Saccharomyces cerevisiae, to generate novel, alternative mating pairs. We find that two yeast cells can mate even when both cells secrete a-like or α-like peptides. Importantly, this is true regardless of whether the cells express the a- or α-mating-type loci, which control the expression of other, sex-specific genes, in addition to the pheromones and pheromone receptors.
  
  
  CONCLUSIONS
  We demonstrate that the asymmetric pheromone modification is not required for successful mating of ascomycete fungi and confirm that, in budding yeast, the primary determinants of mating are the specificity of the receptors and their corresponding pheromones.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Joana
authors.initials: J
authors.lastname: Gonçalves-Sá
authors.forename: Andrew
authors.initials: A
authors.lastname: Murray
mesh_terms: D001203:Ascomycota / Q000502:physiology*; D002459:Cell Fusion; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal; D010675:Pheromones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043563:Receptors, Pheromone / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D010675:Pheromones; D043563:Receptors, Pheromone; D029701:Saccharomyces cerevisiae Proteins