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

Abstract

SUMMARY: Three proteins with characteristic features of class I hydrophobins, designated POH1, POH2 and POH3, were isolated from the basidiomycete PIeurotus ostreatus. Based on N-terminal sequence analyses, their cDNAs were isolated using RT-PCR; the cDNAs and corresponding genes were sequenced and their regulation studied. POHI is expressed in the fruiting bodies but not in vegetative mycelium. The regulation of fWf2 and poH3 is tightly correlated. Both genes are switched off in the fruiting bodies but abundantly expressed in the vegetative mycelium of both monokaryon and dikaryon. POH2 and POH3 were isolated from the culture medium and from aerial hyphae. Co-purified POH2 and POH3 assembledin witro into a protein membrane with a typical rodlet pattern as found previously withother hydrophobins. Similar structures were detected on the surface of aerial hyphae.