Capstan friction model for DNA ejection from bacteriophages

TL;DR

This paper introduces a mechanical model based on capstan friction to explain the DNA ejection dynamics from bacteriophages, aligning with experimental observations of ejection velocity dependence on ejected length.

Contribution

The novel model accounts for the velocity-length relationship in DNA ejection, integrating physical mechanisms with DNA geometry within the capsid.

Findings

Model explains the velocity dependence on ejected length.

Consistent with experimental measurements of DNA ejection.

Provides insights into the physical forces during phage infection.

Abstract

Bacteriophages infect cells by attaching to the outer membrane and injecting their DNA into the cell.The phage DNA is then transcribed by the cell's transcription machinery.A number of physical mechanisms by which DNA can be translocated from the phage capsid into the cell have been identified. A fast ejection driven by the elastic and electrostatic potential energy of the compacted DNA within the viral capsid appears to be used by most phages, at least to initiate infection.In recent in vitro experiments, the speed of DNA translocation from a lambda phage capsid has been measured as a function of ejected length over the entire duration of the event.Here a mechanical model is proposed that is able to explain the observed dependence of exit velocity on ejected length, and that is also consistent with the accepted picture of the geometric arrangement of DNA within the viral capsid.