Interfacial self-assembly of fungal hydrophobins of the lichen-forming ascomycetes Xanthoria parietina and X-ectaneoides

In the symbiotic phenotype of the lichen-forming ascomycetes Xanthoria pari etina and X. ectaneoides, a conglutinate, hydrophilic cortex surrounds a sy stem of aerial hyphae with hydrophobic wall surfaces, In X, parietina freez e-fracture electron microscopy showed that a rodlet layer covers the fungal and algal wall surfaces. Extracts of hot SDS-insoluble wall residues isola ted from both species contained a protein that revealed a rodlet layer upon interfacial self-assembly. The N-terminal sequence of the 10-kDa protein o f X, ectaneoides served to clone cDNA fragments of XEH1 (H1 of X, ectaneoid es) and XPH1 (H1 of X, parietina) by RT-PCR, Genomic DNA blot analysis with both lichenized species and the aposymbiotically cultured symbionts of X, parietina showed that XPH1 and XEH1 ave fungal single copy genes. The deduc ed amino acid sequences of the two encoded proteins were 96% identical and showed the characteristics of class hydrophobins. (C) 2000 Academic Press.