Engineering a rigid protein tunnel for biomolecular detection

Area of Science:

• Biochemistry
• Biophysics
• Materials Science

Background:

• Protein nanopore technology faces challenges in designing stable protein scaffolds for diverse detection conditions.
• Bacterial outer membrane proteins, like ferric hydroxamate uptake component A (FhuA), are potential candidates for nanopore construction but often lack stability.

Purpose of the Study:

• To engineer a robust and stable protein nanopore from a bacterial β-barrel membrane protein for biomolecular sensing.
• To demonstrate the stability and functionality of the engineered nanopore under challenging experimental conditions.

Main Methods:

• Genetic engineering of the FhuA protein.
• Protein refolding techniques to enhance structural integrity.
• Characterization of nanopore stability under varying pH and ionic strength.
• Application of the nanopore as a sensing element for enzymatic activity and aptamer-DNA interactions.

Main Results:

• An extensively engineered FhuA protein formed an unusually stable protein nanopore.
• The engineered nanopore maintained structural and functional integrity in low ion concentrations and highly acidic aqueous phases.
• The FhuA-based nanopore successfully sensed proteolytic enzyme activity at low pH and monitored protein-DNA aptamer kinetics at physiological salt concentrations.

Conclusions:

• Direct genetic engineering coupled with refolding can produce highly stable protein nanopores from β-barrel membrane proteins.
• The engineered FhuA nanopore offers a robust platform for biomolecular sensing under a wide range of experimental conditions, overcoming limitations of traditional protein nanopores.