Genetic regulation of emergent growth in Schizophyllum commune

Abstract

After a period of juvenile growth, Schizophyllum commune starts to transcribe genes for a number of abundant cell-wall proteins that are excreted into the medium by submerged hyphae but become part of the cell wall in emergent structures. The dikaryon transcribes the genes SC1, SC3, SC4, and SC6 that encode hydrophobins and SC7 and SC14 that encode hydrophilic wall proteins of unknown function. Of these, only the SC3 gene is highly transcribed in the monokaryon. The SC3p hydrophobin forms an insoluble hydrophobic rodlet layer by interfacial self-assembly at the outer surface of aerial hyphae of both monokaryon and dikaryon. The SC4p hydrophobin forms an insoluble membrane separating the extracellular matrix surrounding dikaryotic hyphae of the plectenchyma from air cavities in the fruit bodies while the product of the SC7 gene is found within the extracellular matrix. However, these plectenchyma hyphae do not express the SC3 gene. Because SC3 activity is suppressed in a MATA= MATB # heterokaryon and a MATAx matBCon homokaryon, interaction between different B mating-type gene products appears responsible for suppression of SC3 in the hyphae that form the plectenchyma. On the other hand, in aerial hyphae of the MATA# MATB# heterokaryon the binucleate state of the hyphae appears disrupted and this is accompanied by expression of SC3 only, as in the monokaryon. This suggests that regulation of specific genes by the products of different MATB genes only occurs when these genes are present in closely paired nuclei. Thus, spatial differences in gene expression during emergent growth in the MATA # MATB# heterokaryon may occur by regulation of the nuclear distribution.Key words: Schizophyllum commune development, hydrophobins in development, mating-type genes in Schizophyllum, fruit-body development, emergent growth.Rksurnk : Aprbs une pCriode juvknile, le Schizophyllum commune commence a transcrire des gbnes codant pour de nombreuses protCines pariktales excrCtCes dans le milieu en conditions submergies, mais devenant parties de la paroi cellulaire dans les structures CmergCes. Les dicaryons transcrivent les gbnes SC1, SC3, SC4 et SC6 codant pour des hydrophobines, et les g h e s SC7 et SC14 codant pour des protCines pariCtales hydrophyles de fonction inconnue. De ceux-~i, seul le gbne SC3 est fortement transcrit chez le monocaryon. L'hydrophobine pSC3 forme une couche de bdtonnets hydrophobes insolubles, par assemblage interfacial la surface externe des hyphes aCriens des monocaryons ainsi que des dicaryons. L'hydrophobine pSC4 forme une membrane insoluble sCparant la matrice extracellulaire en enveloppant les hyphes dicaryotes au niveau du plectenchyme des cavitCs aCrienes de la fructification, alors que le produit du gbne SC7 se retrouve a llintCrieur de la matrice extracellulaire. Les hyphes de ces plectenchymes n'expriment cependant pas le gbne SC3. Puisque l'activite du SC3 est supprimCe chez un hCtCrocaryon MATA = MAE! # et un homocaryon MATAx matBCO", I'interaction entre diffCrents gbnes du type B de compatibilit...

ldentif ication of three differentially expressed hydrophobins in Pleurotus ostreatus (oyster mushroom)

“…O n the other hand, POHl shares only 53-7 '/o and 52.4 YO identity with POH2 and POH3, respectively, and this hydrophobin groups together with SC1, SC4 and SC6 (S. commune), which like ABHl and ABH2 (A. bisporus) are mainly, or exclusively, found in the fruiting bodies. SC4 and ABHl have been found to assemble at the surface of air channels, providing them with a hydrophobic layer (Wessels et al, 1995;Lugones et at., 1996). We surmise the same location for POHl but have been unable to prove this because immunolocalization of POHl was not successful.…”

“…However, hyphae that constitute fruiting bodies contain little or no SC3 hydrophobin Asgeirsdottir et al, 1995) ; these hyphae express different hydrophobins (SC1, SC4 and SC6; Mulder & Wessels, 1986). SC4 hydrophobin lines air channels in these fruiting bodies and provides them with a hydrophobic surface (Wessels et al, 1995).…”

Surface Modifications Created by Using Engineered Hydrophobins

“…Moreover, they provide gas channels in fruiting bodies and lichens with a hydrophobic layer, which probably provides for more efficient gas exchange under wet conditions (14,16,27,29,31). Hydrophobins are also involved in the attachment of hyphae to hydrophobic surfaces (27, 37) and in the sensing thereof (22), which are important initial steps of pathogenic interactions before penetration and infection of the host can occur.The basidiomycete Schizophyllum commune contains at least four class I hydrophobin genes: SC1, SC3, SC4, and SC6 (6,11,17,33). SC3 is the best-characterized class I hydrophobin.…”

“…The basidiomycete Schizophyllum commune contains at least four class I hydrophobin genes: SC1, SC3, SC4, and SC6 (6,11,17,33). SC3 is the best-characterized class I hydrophobin.…”

Identification of a Hydrophobin Gene That is Developmentally Regulated in the Ectomycorrhizal Fungus Tricholoma terreum

“…Hydrophobins are a class of fungal cell wall proteins involved in making cell-cell or cell-surface contact (13,47,49,50,53). They are essential for the growth of hyphae from a hydrophilic medium into the air.…”