Coupling of actin hydrolysis and polymerization: Reduced description with two nucleotide states

TL;DR

This paper presents a simplified two-state model of actin filament polymerization that incorporates cooperative ATP hydrolysis, predicting steady-state properties like ATP-actin cap size and island distribution.

Contribution

It introduces a novel reduced two-state model with cooperative cleavage to better understand actin filament dynamics.

Findings

Predicts ATP-actin cap size at steady state

Describes ATP-actin island size distribution

Quantifies cleavage flux in cooperative hydrolysis

Abstract

The polymerization of actin filaments is coupled to the hydrolysis of adenosine triphosphate (ATP), which involves both the cleavage of ATP and the release of inorganic phosphate. We describe hydrolysis by a reduced two-state model with a cooperative cleavage mechanism, where the cleavage rate depends on the state of the neighboring actin protomer in a filament. We obtain theoretical predictions of experimentally accessible steady state quantities such as the size of the ATP-actin cap, the size distribution of ATP-actin islands, and the cleavage flux for cooperative cleavage mechanisms.