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: Foams remain an invaluable part of the food engineer's arsenal. Unfortunately the number of new molecules available to stabilise foams is starting to dwindle. Partially, this is due to the difficulties of finding new species with favourable properties and, in many respects, this trend is led by a commercial need to make food labels ‘green’.Food grade proteins offer a number of potential solutions, as well as some excellent physical properties, when at the air–water interface. This review will use the example of hydrophobins as useful proteins finding applications within the food industry. It will also serve as a case study to examine potential methods to identify other new and potentially useful molecules.Current Opinion in Colloid & Interface Science 08/2013; 18(4):292–301. · 6.63 Impact Factor
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ABSTRACT: Poly(ethylene terephthalate), PET, can be functionalised and/or recycled via hydrolysis by microbial cutinases. The rate of hydrolysis is however low. Here we tested whether hydrophobins (HFBs), small secreted fungal proteins containing eight positionally conserved cysteine residues, are able to enhance the rate of enzymatic hydrolysis of PET. Species of the fungal genus Trichoderma have the most proliferated arsenal of class II hydrophobin encoding genes among fungi. To this end, we studied two novel class II HFBs (HFB4 and HFB7) of Trichoderma. HFB4 and HFB7, produced in E. coli as fusions to the C-terminus of glutathione-S-transferase (GST), exhibited subtle structural differences reflected in hydrophobicity plots which correlated with unequal hydrophobicity and hydrophily, respectively, of particular amino acid residues. Both proteins exhibited a dosage-dependent stimulation effect on PET hydrolysis by cutinase from Humicola insolens with HFB4 displaying an adsorption isotherm-like behaviour, whereas HFB7 was active only at very low concentrations and behaved inhibitory beyond them. We conclude that class II HFBs can stimulate the activity of cutinases on PET, but individual HFBs can display different properties. The present findings will contribute to further exploitation of hydrophobins to assist enzymatic hydrolysis of aromatic-aliphatic polyesters like PET.Applied and environmental microbiology 05/2013; · 3.69 Impact Factor
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ABSTRACT: The fungal hydrophobins are small proteins that are able to spontaneously self-assemble into amphipathic monolayers at hydrophobic:hydrophilic interfaces. These protein monolayers can reverse the wettability of a surface, making them suitable for increasing the biocompatibility of many hydrophobic materials. The self-assembling properties and amphipathic nature of hydrophobins make them attractive candidates for biotechnological applications. Recently, there have been significant advances in the understanding of the structure and assembly of these remarkable proteins. This opens up the way for engineering of these proteins to encompass novel functions and for the use of hydrophobins in modification of nanomaterials. This review highlights the important structural aspects of the hydrophobins and the mechanisms by which they assemble and describes recent exciting developments in the use of hydrophobins for cell attachment, drug delivery, and protein purification.Biopolymers 07/2013; · 2.88 Impact Factor