Nature-inspired material binding peptides with versatile polyester affinities and binding strengths

Area of Science:

• Biomaterials science
• Polymer chemistry
• Protein engineering

Background:

• Biodegradable polyesters, including polyhydroxyalkanoates (PHAs), are crucial in biomedicine but lack inherent functional groups for targeted applications.
• Native GAPs (e.g., phasins) possess polymer-binding and surfactant properties, offering a model for surface functionalization.

Purpose of the Study:

• To engineer small material binding peptides (MBPs) for functionalizing polyester surfaces.
• To assess the binding affinity and specificity of these MBPs to different PHAs.
• To demonstrate the utility of MBPs for immobilizing cargo proteins and modifying polyester surfaces.

Main Methods:

• Rational design of amphiphilic peptides based on phasins (PhaF and PhaI) from Pseudomonas putida, resulting in MinP and MinI.
• In vivo fluorescence studies to evaluate peptide binding selectivity.
• In vitro binding assays using Langmuir-Blodgett technique and ellipsometry to determine dissociation constants (K_D).
• Atomic force microscopy (AFM) and Brewster angle microscopy (BAM) to analyze surface morphology changes.

Main Results:

• Engineered peptides (MinP and MinI) showed high-affinity binding (nM K_D) to PHB and PHOH polyesters in vitro.
• Selective in vivo binding of peptides to PHOH was observed.
• Significant morphological changes on PHOH surfaces after peptide adsorption.
• Successful immobilization of cargo proteins onto polyester surfaces using the MBPs.
• MBPs also demonstrated binding to polyethylene terephthalate (PET).

Conclusions:

• Redesigning phasin amphiphilicity yields high-affinity, albeit lower specificity, MBPs for polyesters in vitro.
• These MBPs can effectively functionalize PHA surfaces and immobilize cargo proteins.
• The demonstrated binding to PET suggests broader potential for modifying synthetic polyesters.