3 research outputs found
Hydrophobins: multifunctional biosurfactants for interface engineering
Abstract Hydrophobins are highly surface-active proteins that have versatile potential as agents for interface engineering. Due to the large and growing number of unique hydrophobin sequences identified, there is growing potential to engineer variants for particular applications using protein engineering and other approaches. Recent applications and advancements in hydrophobin technologies and production strategies are reviewed. The application space of hydrophobins is large and growing, including hydrophobic drug solubilization and delivery, protein purification tags, tools for protein and cell immobilization, antimicrobial coatings, biosensors, biomineralization templates and emulsifying agents. While there is significant promise for their use in a wide range of applications, developing new production strategies is a key need to improve on low recombinant yields to enable their use in broader applications; further optimization of expression systems and yields remains a challenge in order to use designed hydrophobin in commercial applications
A Structural and Functional Role for Disulfide Bonds in a Class II Hydrophobin
Hydrophobins
are multifunctional, highly surface active proteins
produced in filamentous fungi and can be identified by eight conserved
cysteine residues, which form four disulfide bridges. These proteins
can be subdivided into two classes based on their hydropathy profiles,
solubility, and structures formed upon interfacial assembly. Here,
we probe the structural and functional roles of disulfide bonds for
a class II hydrophobin in different interfacial contexts by reducing
its disulfides with 1,4-dithiothreitol and blocking the free thiols
with iodoacetamide and then examining the protein secondary structure,
emulsification capability, hydrophobic surface wetting, and solution
self-assembly. Changes in circular dichroism spectra upon reduction
and blocking of disulfides are consistent with an increase in the
level of random coil secondary structure. Emulsification of octane
in water using reduced and unreduced forms of class II hydrophobin
showed a substantial loss of emulsification ability without disulfides
and stable emulsion formation for hydrophobin with disulfides. Additionally,
water contact angle measurements performed on polytetrafluoroethylene
treated with solutions of reduced and unreduced hydrophobin showed
efficient wetting of the hydrophobic surface for unreduced samples
only. Lastly, Förster resonance energy transfer (FRET) was
used to assess the role of disulfides in self-assembly in solution,
and near complete loss of the FRET signal is consistent with a model
in which solution self-assembly does not occur after reduction and
blocking of the disulfides. From this, we conclude that, in contrast
to class I hydrophobins, the disulfides of this class II hydrophobin
are required for protein structural stability, surface activity at
both liquid–liquid and solid–liquid interfaces, and
solution self-assembly