title: SC3 and SC4 hydrophobins have distinct roles in formation of aerial structures in dikaryons of Schizophyllum commune.
abstract: Two monokaryons of Schizophyllum commune can form a fertile dikaryon when the mating-type genes differ. Monokaryons form sterile aerial hyphae, while dikaryons also form fruiting bodies that function in sexual reproduction. The SC3 hydrophobin gene is expressed both in monokaryons and in dikaryons. The SC4 hydrophobin is dikaryon specific. In the monokaryon, SC3 lowers the water surface tension, coats aerial hyphae with a hydrophobic layer and mediates attachment of hyphae to hydrophobic surfaces. The SC4 protein lines gas channels within fruiting bodies with a hydrophobic membrane. Using gene disruptions, in this study, we show that in dikaryons SC3 fulfils the same roles as in monokaryons. SC4, on the other hand, has a role within fruiting bodies. In contrast to gas channels in fruiting bodies of the wild type, those of a DeltaSC4 strain easily filled with water. Thus, SC4 prevents gas channels filling with water under wet conditions, probably serving uninterrupted gas exchange. Other dikaryon-specific hydrophobin genes, SC1 and SC6, apparently do not substitute for the SC4 gene. In addition, by expressing the SC4 gene behind the SC3 promoter in a DeltaSC3 monokaryon, it was shown that SC4 cannot fully substitute for SC3, indicating that both hydrophobins evolved to fulfil specific functions.
authors.affiliation: Groningen Biomolecular Sciences and Biotechnology Institute, Laboratory of Molecular Plant Biology and Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands. M.A.van.Wetter@biol.rug.nl
authors.forename: M A
authors.initials: MA
authors.lastname: van Wetter
authors.forename: H A
authors.initials: HA
authors.lastname: Wösten
authors.forename: J G
authors.initials: JG
authors.lastname: Wessels
mesh_terms: D002448:Cell Adhesion; D002467:Cell Nucleus / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D011994:Recombinant Proteins / Q000096:biosynthesis; D012098:Reproduction; D012567:Schizophyllum / Q000166:cytology* / Q000235:genetics; D013500:Surface Tension
chemical_list: D005656:Fungal Proteins; D011994:Recombinant Proteins