Squeezing a single polypeptide through a nanopore

Abstract

We have already seen a decade of single-molecule science involving protein nanopores, and many lessons have been learned from the extensive studies in this exciting realm. Given the promise of the single-molecule nanopore technique for ultra-rapid sequencing of nucleic acids, most of these investigations have been focused on understanding the transit of single-stranded DNA through a protein nanopore. In contrast, the biophysical and biotechnological applications of polypeptide translocation through a protein nanopore have not been pursued as aggressively. However, recent explorations have shown that a mechanistic understanding of polypeptide translocation at unprecedented single-molecule resolution can be achieved using high-resolution, time-resolved single-channel electrical recordings with nanopores and protein design. Moreover, these efforts have begun to unravel the complexity of the protein–pore interactions that involve various thermodynamic forces. Finally, combining recordings of single-channel electrical currents through nanopores with protein engineering proves to be not only a novel single-molecule analytical tool for the detection, examination, and characterization of polypeptides, but also a critical element for prospective high-throughput screening devices in drug design and proteomics.