Bioengineering a Single-Protein Junction.

Area of Science:

• Bioelectronics
• Nanotechnology
• Protein Engineering

Background:

• Designing nanoscale electronic platforms for in vivo determinations requires interfacing biomolecular sensing units with electronic platforms for signal transduction.
• Understanding the electrical signatures of biomolecular circuits is crucial for tailoring their electrical properties.

Purpose of the Study:

• To demonstrate bioengineered charge transport in a single-protein electrical contact.
• To investigate the effect of a single point-site mutation on protein charge transport behavior.

Main Methods:

• Fabrication of single-protein electrical contacts using Cu-azurin.
• Introduction of a single point-site mutation at the docking hydrophobic patch.
• Spectroscopic studies and molecular-dynamics simulations.
• Density Functional Theory (DFT) computations of frontier orbitals.

Main Results:

• A single mutation dramatically altered the charge transport regime from Cu-mediated two-step transport to direct coherent tunneling.
• Minor structural distortion of the protein blue Cu site was observed.
• Protein folding structures were preserved in the single-protein junction.
• DFT analysis suggested Cu center participation in the observed charge transport differences.

Conclusions:

• Demonstrated direct control over charge transport in a protein backbone via external mutagenesis.
• Established a nanoscale platform for studying structure-related biological electron transfer.
• Highlighted the potential of bioengineering for tailoring protein electrical properties in bioelectronic devices.