Actin filaments growing against a barrier with fluctuating shape

TL;DR

This paper investigates how actin filaments generate force against a fluctuating, non-rigid barrier, revealing that barrier shape fluctuations significantly influence force production and depend on the relative dynamics of filaments and barrier.

Contribution

It introduces a model combining actin filament growth with a fluctuating barrier described by KPZ dynamics, highlighting the impact of barrier fluctuations on force generation.

Findings

Barrier fluctuations alter force-velocity relationships.

The relative timescales of filament and barrier dynamics are crucial.

Analytical mean-field results agree with simulations.

Abstract

We study force generation by a set of parallel actin filaments growing against a non-rigid obstacle, in presence of an external load. The filaments polymerize by either moving the whole obstacle, with a large energy cost, or by causing local distortion in its shape which costs much less energy. The non-rigid obstacle also has local thermal fluctuations due to which its shape can change with time and we describe this using fluctuations in the height profile of a one dimensional interface with Kardar-Parisi-Zhang dynamics. We find the shape fluctuations of the barrier strongly affects the force generation mechanism. The qualitative nature of the force-velocity curve is crucially determined by the relative time-scale of filament and barrier dynamics. The height profile of the barrier also shows interesting variation with the external load. Our analytical calculation within mean-field theory shows reasonable agreement with our simulation results.