Self-Assembled Hydrophobin Protein Films at the Air-Water Interface: Structural Analysis and Molecular Engineering

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• 作者：Gé ; za R. Szilvay ; Arja Paananen ; Katri Laurikainen ; Elina Vuorimaa ; Helge Lemmetyinen ; Jouko Peltonen ; Markus B. Linder
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：March 6, 2007
• 年：2007
• 卷：46
• 期：9
• 页码：2345 - 2354
• 全文大小：651K
• 年卷期：v.46,no.9(March 6, 2007)
• ISSN：1520-4995

文摘

Hydrophobins are amphiphilic proteins produced by filamentous fungi. They function in avariety of roles that involve interfacial interactions, as in growth through the air-water interface, adhesionto surfaces, and formation of coatings on various fungal structures. In this work, we have studied theformation 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-waterinterface. 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 closerstructural analysis of the film was made. The method involved picking up the surface film onto a solidsubstrate and imaging the surface by atomic force microscopy. High-resolution images were obtainedshowing both the hydrophilic and hydrophobic sides of the film at nanometer resolution. It was foundthat the hydrophobin film had a highly ordered structure. To study the orientation of molecules and toobtain 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 theunusual interfacial properties of this type of hydrophobins are due to specific molecular interactions whichlead 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 surfaceelasticity of the hydrophobin film.