IDENTIFICATION OF 3 DIFFERENTIALLY EXPRESSED HYDROPHOBINS IN PLEUROTUS-OSTREATUS (OYSTER MUSHROOM)

Three proteins with characteristic features of class I hydrophobins, d esignated POH1, POH2 and POH3, were isolated from the basidiomycete Pl eurotus ostreatus. Based on N-terminal sequence analyses, their cDNAs were isolated using RT-PCR; the cDNAs and corresponding genes were seq uenced and their regulation studied. POH1 is expressed in the fruiting bodies but not in vegetative mycelium. The regulation of POH2 and POH 3 is tightly correlated. Both genes are switched off in the fruiting b odies but abundantly expressed in the vegetative mycelium of both mono karyon and dikaryon. POH2 and POH3 were isolated from the culture medi um and from aerial hyphae. Co-purified POH2 and POH3 assembled in vitr o into a protein membrane with a typical rodlet pattern as found previ ously with other hydrophobins. Similar structures were detected on the surface of aerial hyphae.