Universal catastrophe time distributions of dynamically unstable polymers

TL;DR

This paper demonstrates that the distribution of catastrophe times in dynamically unstable polymers is generally exponential and explores how finite monomer pools influence this distribution, with implications for understanding biopolymer dynamics.

Contribution

The study derives a universal exponential distribution for catastrophe times and analyzes the impact of finite monomer pools on this distribution, extending prior models.

Findings

Catastrophe time distribution is exponential for a broad class of models.

Depletion of monomers from a finite pool can significantly alter the distribution shape.

Finite-pool effects are important even with minimal impact on polymerization rate.

Abstract

Dynamic instability -- the growth, catastrophe, and shrinkage of quasi-one-dimensional filaments -- has been observed in multiple biopolymers. Scientists have long understood the catastrophic cessation of growth and subsequent depolymerization as arising from the interplay of hydrolysis and polymerization at the tip of the polymer. Here, we show that for a broad class of catastrophe models, the expected catastrophe time distribution is exponential. We show that the distribution shape is insensitive to noise, but that depletion of monomers from a finite pool can dramatically change the distribution shape by reducing the polymerization rate. We derive a form for this finite-pool catastrophe time distribution and show that finite-pool effects can be important even when the depletion of monomers does not greatly alter the polymerization rate.