Fluctuating Currents in Stochastic Thermodynamics II. Energy Conversion and Nonequilibrium Response in Kinesin Models

TL;DR

This paper applies a recent theoretical framework to analyze energy conversion and response in kinesin molecular motor models, revealing non-equilibrium Green-Kubo relations and negative differential mobility under certain conditions.

Contribution

It demonstrates the effectiveness of a new algorithm for analyzing fluctuating currents in stochastic models of biomolecular motors, specifically kinesin.

Findings

Validation of non-equilibrium Green-Kubo relation at stalling

Observation of negative differential mobility for superstalling forces

Effective application of the algorithm to parameter-dependent models

Abstract

Unlike macroscopic engines, the molecular machinery of living cells is strongly affected by fluctuations. Stochastic Thermodynamics uses Markovian jump processes to model the random transitions between the chemical and configurational states of these biological macromolecules. A recently developed theoretical framework [Wachtel, Vollmer, Altaner: "Fluctuating Currents in Stochastic Thermodynamics I. Gauge Invariance of Asymptotic Statistics"] provides a simple algorithm for the determination of macroscopic currents and correlation integrals of arbitrary fluctuating currents. Here, we use it to discuss energy conversion and nonequilibrium response in different models for the molecular motor kinesin. Methodologically, our results demonstrate the effectiveness of the algorithm in dealing with parameter-dependent stochastic models. For the concrete biophysical problem our results reveal two interesting features in experimentally accessible parameter regions: The validity of a non-equilibrium Green--Kubo relation at mechanical stalling as well as negative differential mobility for superstalling forces.