Oral Presentation 2014 International Biophysics Congress

Interface-triggered formation of functional amyloid by hydrophobin proteins (#170)

Margie Sunde 1 , Chi Le Lan Pham 1 , Ann H. Kwan 1
  1. University of Sydney, Sydney, NSW, Australia

The hydrophobins are a family of small proteins found in all filamentous fungi. They self-assemble specifically at hydrophilic:hydrophobic interfaces to form highly ordered amphipathic monolayers. Some hydrophobins form amphipathic monolayers that are composed of amyloid fibrils that share many of the structural characteristics of disease-associated amyloid fibrils. In fungi, the amyloid layer plays important functional roles in the life-cycle and may be involved in adhesion to host surfaces, formation of infectious structures or immune evasion. By comparing the structure and assembly process for different hydrophobins from a range of fungi we have been able to identify the key features of these proteins that direct the aggregation process. We have probed the process of self-assembly by hydrophobins using mutagenesis, in order to identify the conformational changes that occur upon fibril formation and the residues that form the ordered cross-beta core of the fibrils. Hydrophobin amyloid assembly is unusual in that it is triggered by the presence of a hydrophobic:hydrophilic interface and we find that surface tension is critical for the conformational changes which occur upon amyloid formation. The robust, amphipathic, self-assembling nature of hydrophobin amyloid gives the fungus a functional advantage.