title: The gprA and gprB genes encode putative G protein-coupled receptors required for self-fertilization in Aspergillus nidulans.
abstract: The filamentous fungus Aspergillus nidulans possesses both asexual and sexual reproductive cycles. Sexual fruiting bodies (cleistothecia) can be formed in both homothallic (self) and heterothallic (outcross) conditions. In this study, we characterized two genes, gprA and gprB, that are predicted to encode putative G protein-coupled receptors (GPCRs) similar to fungal pheromone receptors. Deletion (Delta) of gprA or gprB resulted in the production of a few small cleistothecia carrying a reduced number of ascospores, whereas DeltagprADeltagprB eliminated fruiting body formation in homothallic conditions. However, nullifying gprA and/or gprB did not affect vegetative growth, asexual sporulation, Hülle cell formation or even cleistothecia formation in outcross, indicating that GprA and GprB are specifically required for self-fertilization. The gprA and gprB genes encode two transcripts and, for both genes, larger transcripts are detectable during vegetative growth and asexual development whereas smaller transcripts accumulate during sexual development. Upregulation of nsdD encoding a key sexual developmental activator resulted in the production of barren cleistothecia in the DeltagprADeltagprB mutant, suggesting that NsdD can partially rescue the developmental defects caused by deletion of GPCRs and that GprA/B-mediated signalling may activate other genes necessary for maturation of cleistothecia and ascosporogenesis. Deletion of gprA and/or gprB suppressed growth defects caused by DeltagprD, implying that GprA/B function downstream of GprD-mediated negative control of sexual development.
authors.affiliation: Department of Food Microbiology and Toxicology, Food Research Institute, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Jeong-Ah
authors.initials: JA
authors.lastname: Seo
authors.forename: Kap-Hoon
authors.initials: KH
authors.lastname: Han
authors.forename: Jae-Hyuk
authors.initials: JH
authors.lastname: Yu
mesh_terms: D001233:Aspergillus nidulans / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D048690:Fruiting Bodies, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000378:metabolism; D008954:Models, Biological; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide / Q000235:genetics / Q000378:metabolism; D043563:Receptors, Pheromone / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D046468:Sexual Development / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D018398:Homeodomain Proteins; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide; D043563:Receptors, Pheromone; C081863:STE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C412005:SteA protein, Emericella nidulans; D014157:Transcription Factors