Self-assembled films of hydrophobin protein HFBIII from Trichoderma reesei

Hydrophobins are a group of small amphiphilic proteins which are known to self-assemble on interfaces. They contain eight conserved cysteine residues, which make four disulfide bridges. A new hydrophobin protein, HFBIII, from the fungus Trichoderma reesei contains one extra cysteine residue, giving the protein a naturally reactive site. The self-assembly of hydrophobin protein HFBIII was studied using grazing-incidence X-ray diffraction and reflectivity. HFBIII self-assembles into a hexagonally ordered monolayer at an air/water interface and also forms crystalline coatings on a silicon substrate. The lattice constants for the hexagonal coatings are a = b = 56.5 Å, [gamma] = 120°. The self-assembled structure in the HFBIII film is very similar to those formed by two other T. reesei hydrophobins, HFBI and HFBII.