Interactions of hydrophobin proteins in solution studied by small-angle X-ray scattering
Kaisa Kisko1, Géza R Szilvay, Ulla Vainio
1Department of Physical Sciences, University of Helsinki, FI-00014 HU, Finland. kaisa.kisko@helsinki.fi
Biophysical Journal
|September 11, 2007
Summary
Hydrophobins HFBI and HFBII from Trichoderma reesei primarily form tetramers in aqueous solution. Their self-assembly, driven by hydrophobic effects, is influenced by salts and ethanol, impacting their role in fungal surface interactions.
Area of Science:
- Biochemistry
- Protein Science
- Mycology
Background:
- Hydrophobins are fungal proteins with high surface activity.
- They self-assemble on interfaces, aiding fungal attachment.
- Hydrophobins are soluble in water, suggesting complex solution behavior.
Purpose of the Study:
- To investigate the solution behavior of hydrophobins HFBI and HFBII from Trichoderma reesei.
- To understand the oligomeric state and self-assembly drivers of these hydrophobins.
- To explore the relationship between solution oligomers and self-assembled films.
Main Methods:
- Small-angle X-ray scattering (SAXS) was employed.
- Aqueous solutions of HFBI and HFBII were analyzed.
- Effects of pH, temperature, salts (Hofmeister series), and ethanol were tested.
Main Results:
- HFBI and HFBII predominantly exist as tetramers in solution (0.5-10 mg/ml).
- HFBII assemblies are less stable than HFBI assemblies.
- HFBI tetramers tolerate a pH range of 3-9 and temperatures of 5-60°C.
- Self-association is driven by hydrophobic effects; salts promote larger assemblies, ethanol dissociates tetramers.
Conclusions:
- The tetrameric form is a key oligomeric state for HFBI and HFBII in solution.
- Environmental factors like salts and ethanol modulate hydrophobin assembly.
- Solution oligomers are likely precursors for self-assembled films at interfaces.
