In voltage-driven translocation experiments, an applied voltage across two electrolytic cells connected through a nanopore induces the migration of proteins and other macromolecules across the nanopore. A macromolecule engaging the pore produces detectable ion-current variations very informative on its physical-chemical properties . An increasing accumulation of data [2,3] supports the view that protein translocation across narrow pores is a multistage process characterized by a sequence of dynamical “stall events” (bottlenecks) representing, to some extent, the fingerprint of the passing molecule. We analyze, via molecular dynamics simulations on a coarse-grained model of the protein-pore system, the occurrence of the multistage scenario resulting from the tight coupling between transport and unfolding.
Simulations strongly indicate a relationship between:
We thus argue that a nontrivial inference on the presence of a multistep translocation dynamics can be done from the knowledge of the protein native-state topology. One theoretical challenge is reconstructing the structural properties of proteins from the information conveyed by their multistage dynamics across narrow nanopores .