Hydrophobins are small (ca. 100 amino acids) secreted fungal proteins that are characterized by the presence of eight conserved cysteine residues and by a typical hydropathy pattern. Class I hydrophobins self-assemble at hydrophilic-hydrophobic interfaces into highly insoluble amphipathic membranes, thereby changing the nature of surfaces. Hydrophobic surfaces become hydrophilic, while hydrophilic surfaces become hydrophobic. To see whether surface properties of assembled hydrophobins can be changed, 25 N-terminal residues of the mature SC3 hydrophobin were deleted (TrSC3). In addition, the cell-binding domain of fibronectin (RGD) was fused to the N terminus of mature SC3 (RGD-SC3) and TrSC3 (RGD-TrSC3). Self-assembly and surface activity were not affected by these modifications. However, physiochemical properties at the hydrophilic side of the assembled hydrophobin did change. This was demonstrated by a change in wettability and by enhanced growth of fibroblasts on Teflon-coated with RGD-SC3, TrSC3, or RGD-TrSC3 compared to bare Teflon or Teflon coated with SC3. Thus, engineered hydrophobins can be used to functionalize surfaces.Hydrophobins are moderately hydrophobic proteins secreted by fungi. They are characterized by the presence of eight cysteine residues in conserved spacing and by similar hydropathy patterns (30,32,34). Hydrophobins fulfill a broad spectrum of functions. They mediate escape of hyphae from a hydrophilic environment (41) and are involved in the formation of hydrophobic aerial structures such as aerial hyphae (4,23,28,36,38), spores (2,3,10,21,22), and fruiting bodies (5, 13). Moreover, they provide gas channels in fruiting bodies and lichens with a hydrophobic layer, which probably provides for more efficient gas exchange under wet conditions (14,16,27,29,31). Hydrophobins are also involved in the attachment of hyphae to hydrophobic surfaces (27, 37) and in the sensing thereof (22), which are important initial steps of pathogenic interactions before penetration and infection of the host can occur.The basidiomycete Schizophyllum commune contains at least four class I hydrophobin genes: SC1, SC3, SC4, and SC6 (6,11,17,33). SC3 is the best-characterized class I hydrophobin. It is involved in the formation of aerial hyphae (28,36,38,41) and in the attachment of hyphae to hydrophobic surfaces (37). Upon contact with hydrophilic-hydrophobic interfaces SC3 monomers self-assemble into a highly insoluble amphipathic membrane (36,37,40). This is accompanied with an increase in ␤-sheet structure at the water-air interface and by increase in ␣-helical structure at the water-hydrophobic solid interface (6). The latter form is an intermediate to the form with increased ␤-sheet structure (35). Upon self-assembly of SC3 at the waterair interface the water surface tension is reduced to as low as 24 mJ m Ϫ2 , which makes assembled SC3 one of the most powerful biosurfactants known to date (26,41). When a hydrophobic solid is incubated in an aqueous hydrophobin solution, an amphipathic membrane of the protein...

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The centric diatom Cyclotella cryptica and two strains of the pennate diatom Phaeodactylum tricornutum were grown under low and high light intensities (300 lux and 3,000 lux) over 4±6 weeks. Growth was monitored by repetitive cell count. The culture media were replaced weekly to avoid morphological and biochemical alterations caused by nutrient depletion. The ultrastructure of the cells was examined by transmission electron microscopy. Alterations in the light-harvesting antenna systems were investigated by Western immunoblotting. Both diatoms reduced the plastid area, i.e. decreased the amount of thylakoid lamellae, under high light intensity. The thylakoids still ran in groups of three with parallel orientation within the chloroplasts. The girdle band lamellae were not aected. The amounts of storage compounds and vacuoles increased. SDS-PAGE of total cell protein followed by Western immunoblotting with antisera directed against subunits of the light-harvesting antenna systems of C. cryptica (cc-antiserum) and the cryptophyte Cryptomonas maculata (cmac-antiserum) revealed that both diatoms reduced the amount of antenna polypeptides under increased light intensity. The cc-antiserum immunodecorated two bands with relative molecular masses (M r) of 18,000 and 22,000 in C. cryptica. Both decreased under high light conditions to 67.26.1%. Five to seven bands in the M r range of 14,000±27,000 were recognized in P. tricornutum. They decreased to 835.3%. Furthermore, the immunolabeling pattern for both strains diered under the two light regimes. The cmac-antiserum immunodecorated two polypeptides with M r of 24,000 and 23,000 in C. cryptica, while both strains of P. tricornutum had ®ve polypeptides in the M r range of 14,000±24,000 that showed some dierences in staining intensities between the two strains and in response to the light intensity applied.