Hydrophobin gene expression affects hyphal wall composition in Schizophyllum commune

Disruption of the SC3 hydrophobin gene of Schizophyllum commune (Delta SC3 strain) affected the composition of the cell wall. Compared to a wild-type strain the amount of mucilage (i.e., water-soluble (1-3)beta -glucan with single glucose residues attached by (I-G)P-linkages) increased considerably, while the amount of alkali-resistant glucan (linked to chitin) decreased. Reintroduction of the SC3 gene or other hydrophobins genes expressed behind the SC3 promotor restored wild-type cell wall composition. However, addition of purified SC3 protein to the medium or growing the Delta SC3 strain in spent medium of the wild-type strain had no effect. In young cultures of wild-type strains of S.commune, not yet expressing SC3, the amount of mucilage was also relatively high. These data show that hydrophobins not only function at hydrophilic/hydrophobic interfaces, as shown previously, but also affect wall composition, (C) 2001 academic Press.