IDENTIFICATION, CHARACTERIZATION, AND IN-SITU DETECTION OF A FRUIT-BODY-SPECIFIC HYDROPHOBIN OF PLEUROTUS-OSTREATUS

Hydrophobins are small (length, about 100 +/- 25 amino acids), cystein e-rich, hydrophobic proteins that are present in large amounts in fung al cell walls, where they form part of the outermost layer (rodlet lay er); sometimes, they can also be secreted into the medium, Different h ydrophobins are associated with different developmental stages of a fu ngus, and their biological functions include protection of the hyphae against desiccation and attack by either bacterial or fungal parasites , hyphal adherence, and the lowering of surface tension of the culture medium to permit aerial growth of the hyphae. We identified and isola ted a hydrophobin (fruit body hydrophobin 1 [Fbh1]) present in fruit b odies but absent in both monokaryotic and dikaryotic mycelia of the ed ible mushroom Pleurotus ostreatus. In order to study the temporal and spatial expression of the fbh1 gene, we determined the N-terminal amin o acid sequence of Fbh1. We also synthesized and cloned the double-str anded cDNA corresponding to the full-length mRNA of Fbh1 to use it as a probe in both Northern blot and in situ hybridization experiments. F bh1 mRNA is detectable in specific parts of the fruit body, and it is absent in other developmental stages.