Role of ATP-hydrolysis in the dynamics of a single actin filament

TL;DR

This paper investigates how ATP hydrolysis mechanisms influence the growth and shrinkage dynamics of single actin filaments, extending previous models to include both filament ends and comparing vectorial and random hydrolysis.

Contribution

It introduces an extended model for actin filament dynamics that incorporates both ends and compares vectorial and random hydrolysis mechanisms.

Findings

Comparison of vectorial and random hydrolysis effects on filament dynamics

Proposed experiments to distinguish hydrolysis mechanisms

Extended model including both filament ends

Abstract

We study the stochastic dynamics of growth and shrinkage of single actin filaments taking into account insertion, removal, and ATP hydrolysis of subunits either according to the vectorial mechanism or to the random mechanism. In a previous work, we developed a model for a single actin or microtubule filament where hydrolysis occurred according to the vectorial mechanism: the filament could grow only from one end, and was in contact with a reservoir of monomers. Here we extend this approach in several ways, by including the dynamics of both ends and by comparing two possible mechanisms of ATP hydrolysis. Our emphasis is mainly on two possible limiting models for the mechanism of hydrolysis within a single filament, namely the vectorial or the random model. We propose a set of experiments to test the nature of the precise mechanism of hydrolysis within actin filaments.