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.

Applications of hydrophobins: current state and perspectives

“…At higher ratios, the adhesiveness of HFBI (mutant) to a solid surface decreased indicating a change in preference for oligomerization over dissociation and binding to a surface. Self-assembly of HFBI and HFBII at the water-air interface is not accompanied by a change in secondary structure or ultrastructure (Askolin et al 2006;Paananen et al 2003;Wösten and de Vocht 2000). Maximal lowering of the water surface tension was obtained within minutes (Askolin et al 2006).…”

“…Self-assembly of HFBI and HFBII at the water-air interface is not accompanied by a change in secondary structure or ultrastructure (Askolin et al 2006;Paananen et al 2003;Wösten and de Vocht 2000). Maximal lowering of the water surface tension was obtained within minutes (Askolin et al 2006). This Transition to the stable β-sheet end form is achieved by high protein concentration, the presence of the polysaccharide schizophyllan (SPG), or the combination of heat or low pH and detergents.…”

“…Maximal lowering of the water surface tension was reached after several hours with SC3 (Askolin et al 2006), while this occurred instantaneously in the case of ABH1 (Agaricus bisporus) (Paslay et al 2013). SC3 in the β-sheet 2 state cannot be removed from a hydrophobic solid with detergent at any temperature or pH Scholtmeijer et al 2009).…”

“…Both class I and class II hydrophobins can be used to disperse hydrophobic solids in water (Wösten et al 1994;de Vocht et al 1998;Lumsdon et al 2005;Askolin et al 2006). High concentrations of non-ionic surfactants are usually used to disperse Teflon particles in aqueous solutions (e.g., in coatings and lubricants).…”

Self-assembled films of hydrophobin protein HFBIII from Trichoderma reesei

“…These arise from the amphiphilic structure of the proteins, where the hydrophobic and hydrophilic parts are separated (Hakanpä ä , Paananen, Askolin et al, 2004;Kwan et al, 2006). Hydrophobins lower the surface tension of water even down to one third (Wö sten et al, 1999;Askolin et al, 2006), adhere to various surfaces and self-assemble on hydrophobic/hydrophilic interfaces. This self-assembly has been demonstrated, for example, on interfaces between air and water, oil and water, and hydrophobic solid and water (Wö sten et al, 1994;Askolin et al, 2006).…”