Rigidity-induced scale invariance in polymer ejection from capsid

Area of Science:

• Biophysics
• Polymer Physics
• Computational Biology

Background:

• The ejection dynamics of flexible polymers from viral capsids through nanopores are well-understood.
• However, the behavior of semiflexible polymers under similar conditions remains largely uncharacterized.

Purpose of the Study:

• To investigate and characterize the ejection dynamics of semiflexible polymers from spherical capsids using computational simulations.
• To compare the ejection mechanisms of semiflexible polymers with those of fully flexible polymers.

Main Methods:

• Molecular dynamics simulations were employed to model the ejection process.
• Simulations focused on semiflexible polymers starting from confined conformations with constant initial monomer density.

Main Results:

• Semiflexible polymer ejection force at the pore is not directly correlated with ejection velocity, unlike flexible polymers.
• Cumulative monomer exit time (t(s)) shows a distinct change with increasing polymer rigidity (κ).
• Ejection involves internal pressure-driven release followed by diffusion-controlled escape, with a crossover in dynamics for the driven portion.

Conclusions:

• Increasing polymer rigidity (κ) induces a crossover in ejection dynamics, resembling a phase transition.
• The study establishes a quantitative relationship for cumulative exit time: t(s)∝N₀⁰.⁵⁵s¹.³³ for rigid polymers.
• A data collapse of exit times across different polymer lengths (N₀) and rigidities (κ) was observed, highlighting universal scaling behaviors.