Fluctuations in Polymer Translocation

TL;DR

This paper models chaperone-assisted polymer translocation through a nanopore, revealing how binding proteins rectify Brownian motion, resulting in directed transport and detailed statistical characterization of the process.

Contribution

It introduces a novel model for polymer translocation driven by chaperone binding, providing analytical results for velocity, diffusion, and large deviation functions.

Findings

Translocation is driven by chaperone binding that inhibits backward motion.

The model computes the diffusion constant and large deviation function.

Results include the full statistical distribution of translocated length.

Abstract

We investigate a model of chaperone-assisted polymer translocation through a nanopore in a membrane. Translocation is driven by irreversible random sequential absorption of chaperone proteins that bind to the polymer on one side of the membrane. The proteins are larger than the pore and hence the backward motion of the polymer is inhibited. This mechanism rectifies Brownian fluctuations and results in an effective force that drags the polymer in a preferred direction. The translocated polymer undergoes an effective biased random walk and we compute the corresponding diffusion constant. Our methods allow us to determine the large deviation function which, in addition to velocity and diffusion constant, contains the entire statistics of the translocated length.