Potentiating Tweezer Affinity to a Protein Interface with Sequence-Defined Macromolecules on Nanoparticles.

Area of Science:

• Biochemistry
• Nanotechnology
• Molecular Biology

Background:

• Survivin, an apoptosis inhibitor, is upregulated in cancers, contributing to chemotherapy resistance.
• Inhibiting survivin's interaction with the CRM1 export receptor is a strategy to overcome resistance.
• Targeting protein-protein interactions (PPIs) is crucial for developing novel cancer therapies.

Purpose of the Study:

• To design and synthesize a novel high avidity inhibitor targeting the survivin-CRM1 interaction.
• To investigate the impact of multivalent presentation and nanoparticle conjugation on inhibitor efficacy.
• To demonstrate efficient cellular delivery and enhanced inhibition of survivin-CRM1 PPI.

Main Methods:

• Utilized supramolecular tweezer motifs, sequence-defined macromolecular scaffolds, and ultrasmall gold nanoparticles (us-AuNPs).
• Employed biophysical techniques like surface plasmon resonance (SPR) and computational analysis (EVILFIT) for affinity and avidity measurements.
• Conjugated tweezer inhibitors to us-AuNPs for enhanced cellular uptake and evaluated their inhibitory effects in HeLa cells.

Main Results:

• Macromolecular tweezer constructs with longer linkers exhibited superior affinity and slower dissociation rates.
• Macromolecular tweezer conjugates alone did not enter cells.
• Immobilization on us-AuNPs enabled efficient cellular transport and increased inhibitor avidity by 100-fold due to increased valency (up to 16).

Conclusions:

• A hierarchical approach combining supramolecular binders, scaffolds, and nanoparticles effectively creates potent inhibitors of the survivin-CRM1 PPI.
• Nanoparticle-mediated delivery overcomes cellular entry limitations of macromolecular inhibitors.
• This strategy offers a promising platform for developing inhibitors against other critical protein-protein interactions in cancer therapy.