Assembly of Hydrophobin class I from Agaricus bisporus produced different amyloid-like fibrils

Abstract

This work studied the extraction, purification, characterization, and assembly of hydrophobin class I from Agaricus bisporus (ABH4). The highest soluble protein concentration was obtained from the pinhead, the extraction and purification were efficient for hydrophobin class I, obtaining a band of 12 kDa. The identified sequence of hydrophobin presented the eight cysteine residues; for the prediction of the structure, hydrophobin presented more alpha helix structures than beta sheets. It was observed that the hydrophobin managed to decrease and increase the contact angle in Teflon and glass, respectively, finding a micellar critical concentration of 221 μg mL⁻¹. ThT experiments demonstrated that the production of fibrils decreased at basic pH, while acidic and neutral pH favoured the formation of fibrils. Likewise, the addition of colloidal Teflon affects the formation of fibrils. Circular dichroism spectra proved that hydrophobin class I undergo changes in its secondary structure, increasing its alpha helix and beta sheet content after vortexing. It was observed that the analysis by scanning electron microscopy and atomic force microscopy of the hydrophobin produced different amyloid-like structures in glass and mica.