Mechanisms of Protein Adhesion on Surface Films of Hydrophobin

Abstract

Hydrophobins are adhesive proteins produced by filamentous fungi. They are in many cases secreted into the medium and adsorb readily to a number of different surfaces. They fulfill many different tasks such as the formation of various coatings and mediating adhesion of fungi to surfaces. The mechanism of how hydrophobins adhere and how they mediate fungal adhesion is of interest both from the point of view of fungal biology and for various biotechnical immobilization applications. It has been shown that hydrophobins typically form a monomolecular layer on solid substrates. We are especially interested in how a surface layer of hydrophobin can mediate the adhesion of a second layer of another protein. In this work we systematically studied how proteins adsorb onto hydrophobins that are bound as monomolecular layers on nonpolar surfaces. We found that several types of proteins readily adsorb onto hydrophobins, but only under defined conditions of pH and ionic strength. The binding conditions were also highly dependent on the adhering protein. By studying solution conditions such as pH and ionic strength, we conclude that the surface adhesion is due to selective Coulombic charge interactions. We conclude that hydrophobins can transform a nonpolar surface into one that efficiently recruits other proteins by charge interactions.

Immobilization of anti-CD31 antibody on electrospun poly(ɛ-caprolactone) scaffolds through hydrophobins for specific adhesion of endothelial cells

“…The isoelectric point (pI) of HFBI is 5.7, so the surface charge of HFBI-coated PCL films should be negative at pH 7.4 [25]. The negative charges may improve the hemocompatibility of the modified PCL films, thus playing a role in maintaining the patency of the vascular grafts.…”

“…The antibody was successfully anchored on the HFBI surface through protein-protein interactions (e.g., electrostatic, van der Waals, hydrogen bonding and hydrophilic interactions). The pI of IgG is 7-9.5; therefore HFBI and IgG have opposite charges at pH 7.4 [25] and electrostatic interactions may be the predominant binding mechanism. The FITC labeled secondary antibody was able to bind to the primary antibody, indicating that the adsorbed anti-CD31 antibody retained its binding activity.…”

Phylogenetic, genomic organization and expression analysis of hydrophobin genes in the ectomycorrhizal basidiomycete Laccaria bicolor

“…As hydrophobins are regulated by changes in the external environment (e.g. during host colonization; Wessel, 1996) or to aid host colonization (Corvis et al, 2005(Corvis et al, , 2006(Corvis et al, , 2007Qin et al, 2007;Zhao, 2007;Aimanianda et al, 2009;Wang et al, 2010), it is possible that the large variety of hydrophobins encoded by L. bicolor strains are a necessary adaptation to aid in the colonization of different plant hosts. 450…”

On‐the‐Spot Immobilization of Quantum Dots, Graphene Oxide, and Proteins via Hydrophobins

“…Since Vmh2 in 60% ethanol solution is endowed with positive electrostatic potential (measured by electrophoretic mobility), [ 71 ] negatively charged glass surfaces obtained by air plasma treatment were appropriate to enhance the studied protein binding. Moreover, given that the adhesion energy of the protein layer is dominated by hydrophobic and Coulombic charge interactions, [ 75,76 ] the hydrophobin orientation will determine the effi ciency of immobilization of the interested molecules to the modifi ed surface.…”