Interaction and comparison of a class I hydrophobin from Schizophyllum commune and class II hydrophobins from Trichoderma reesei.
ABSTRACT Hydrophobins fulfill a wide spectrum of functions in fungal growth and development. These proteins self-assemble at hydrophilic-hydrophobic interfaces into amphipathic membranes. Hydrophobins are divided into two classes based on their hydropathy patterns and solubility. We show here that the properties of the class II hydrophobins HFBI and HFBII of Trichoderma reesei differ from those of the class I hydrophobin SC3 of Schizophyllum commune. In contrast to SC3, self-assembly of HFBI and HFBII at the water-air interface was neither accompanied by a change in secondary structure nor by a change in ultrastructure. Moreover, maximal lowering of the water surface tension was obtained instantly or took several minutes in the case of HFBII and HFBI, respectively. In contrast, it took several hours in the case of SC3. Oil emulsions prepared with HFBI and SC3 were more stable than those of HFBII, and HFBI and SC3 also interacted more strongly with the hydrophobic Teflon surface making it wettable. Yet, the HFBI coating did not resist treatment with hot detergent, while that of SC3 remained unaffected. Interaction of all the hydrophobins with Teflon was accompanied with a change in the circular dichroism spectra, indicating the formation of an alpha-helical structure. HFBI and HFBII did not affect self-assembly of the class I hydrophobin SC3 of S. commune and vice versa. However, precipitation of SC3 was reduced by the class II hydrophobins, indicating interaction between the assemblies of both classes of hydrophobins.
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ABSTRACT: Hydrophobins are small fungal surface active proteins that self-assemble at interfaces into films with nanoscale structures. The hydrophobin HFBI from Trichoderma reesei has been shown to associate in solution into tetramers but the role of this association on the function of HFBI has remained unclear. We produced two HFBI variants that showed a significant shift in solution association equilibrium towards the tetramer state. However, this enhanced solution association did not alter the surface properties of the variant HFBIs. The results show that there is not a strong relationship between HFBI solution association state and surface properties such as surface activity.FEBS Letters 07/2007; 581(14):2721-6. · 3.58 Impact Factor
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ABSTRACT: Hydrophobins are small fungal proteins with amphipatic properties and the ability to self-assemble on a hydrophobic/hydrophilic interface; thus, many technical applications for hydrophobins have been suggested. The pathogenic fungus Aspergillus fumigatus expresses the hydrophobins RodA and RodB on the surface of its conidia. RodA is known to be of importance to the pathogenesis of the fungus, while the biological role of RodB is currently unknown. Here, we report the successful expression of both hydrophobins in Pichia pastoris and present fed-batch fermentation yields of 200-300 mg/l fermentation broth. Protein bands of expected sizes were detected by SDS-PAGE and western blotting, and the identity was further confirmed by tandem mass spectrometry. Both proteins were purified using his-affinity chromatography, and the high level of purity was verified by silver-stained SDS-PAGE. Recombinant RodA as well as rRodB were able to convert a glass surface from hydrophilic to hydrophobic similar to native RodA, but only rRodB was able to decrease the hydrophobicity of a Teflon-like surface to the same extent as native RodA, while rRodA showed this ability to a lesser extent. Recombinant RodA and native RodA showed a similar ability to emulsify air in water, while recombinant RodB could also emulsify oil in water better than the control protein bovine serum albumin (BSA). This is to our knowledge the first successful expression of hydrophobins from A. fumigatus in a eukaryote host, which makes it possible to further characterize both hydrophobins. Furthermore, the expression strategy and fed-batch production using P. pastoris may be transferred to hydrophobins from other species.Applied Microbiology and Biotechnology 04/2011; 90(6):1923-32. · 3.81 Impact Factor
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ABSTRACT: Hydrophobins fulfill various physiological functions in fungal development and growth, based on their mechanism of self-assembly at hydrophilic–hydrophobic interfaces into nano-scale, amphipathic membranes. One hydrophobin with an approximate molecular weight of 15kDa, designated Po.HYD1, was purified from aerial hyphae of Pleurotus ostreatus strain Pm039. Ultrastructures of self-assembled films formed by Po.HYD1 on hydrophobic and hydrophilic substrates were revealed by atomic force microscopy (AFM). A monomolecular adsorption layer, thickness ranging from 3.2 to 3.8nm, was observed on the surface of highly oriented pyrolytic graphite (HOPG), while a typical rodlet layer with uniform thickness of 4.2±0.1nm formed on the mica surface. Comparison of CD spectra showed significant secondary structural changes between monomeric and self-assembled states. The spectrum of monomeric Po.HYD1 had a maximum ellipticity at 190nm and a minimum at 209nm, and that of assemblage showed the maximum at 195nm and the minimum shifted to 215–218nm. Po.HYD1 showed high surface activity, based on the dramatic drop of surface tension through self-assembly at the water–air interface. Moreover, Po.HYD1 is capable of stabilizing the emulsion consisting of water and hexane.World Journal of Microbiology and Biotechnology 24(4):501-507. · 1.35 Impact Factor