Abstract
Hydrophobins are amphiphilic proteins produced by filamentous fungi.
They function in a variety of roles that involve interfacial interactions, as
in growth through the air-water interface, adhesion to surfaces, and formation
of coatings on various fungal structures. In this work, we have studied the
formation of films of the class II hydrophobin HFBI from Trichoderma reesei at
the air-water interface. Analysis of hydrophobin aqueous solution drops
showed that a protein film is formed at the air-water interface. This elastic
film was clearly visible, and it appeared to cause the drops to take unusual
shapes. Because adhesion and formation of coatings are important biological
functions for hydrophobins, a closer structural analysis of the film was made.
The method involved picking up the surface film onto a solid substrate and
imaging the surface by atomic force microscopy. High-resolution images were
obtained showing both the hydrophilic and hydrophobic sides of the film at
nanometer resolution. It was found that the hydrophobin film had a highly
ordered structure. To study the orientation of molecules and to obtain further
insight in film formation, we made variants of HFBI that could be site
specifically conjugated. We then used the avidin-biotin interaction as a
probe. On the basis of this work, we suggest that the unusual interfacial
properties of this type of hydrophobins are due to specific molecular
interactions which lead to an ordered network of proteins in the surface films
that have a thickness of only one molecule. The interactions between the
proteins in the network are likely to be responsible for the unusual surface
elasticity of the hydrophobin film.
Original language | English |
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Pages (from-to) | 2345-2354 |
Journal | Biochemistry |
Volume | 46 |
Issue number | 9 |
DOIs | |
Publication status | Published - 2007 |
MoE publication type | A1 Journal article-refereed |
Keywords
- hydrophobins
- filamentous fungi
- Trichoderma reesei
- coatings