Random intermittent search and the tug-of-war model of motor-driven transport

Type
Article

Authors
Newby, Jay
Bressloff, Paul C

KAUST Grant Number
KUK-C1-013-4

Date
2010-04-16

Abstract
We formulate the 'tug-of-war' model of microtubule cargo transport by multiple molecular motors as an intermittent random search for a hidden target. A motor complex consisting of multiple molecular motors with opposing directional preference is modeled using a discrete Markov process. The motors randomly pull each other off of the microtubule so that the state of the motor complex is determined by the number of bound motors. The tug-of-war model prescribes the state transition rates and corresponding cargo velocities in terms of experimentally measured physical parameters. We add space to the resulting Chapman-Kolmogorov (CK) equation so that we can consider delivery of the cargo to a hidden target at an unknown location along the microtubule track. The target represents some subcellular compartment such as a synapse in a neuron's dendrites, and target delivery is modeled as a simple absorption process. Using a quasi-steady-state (QSS) reduction technique we calculate analytical approximations of the mean first passage time (MFPT) to find the target. We show that there exists an optimal adenosine triphosphate (ATP) concentration that minimizes the MFPT for two different cases: (i) the motor complex is composed of equal numbers of kinesin motors bound to two different microtubules (symmetric tug-of-war model) and (ii) the motor complex is composed of different numbers of kinesin and dynein motors bound to a single microtubule (asymmetric tug-of-war model). © 2010 IOP Publishing Ltd.

Citation
Newby J, Bressloff PC (2010) Random intermittent search and the tug-of-war model of motor-driven transport. Journal of Statistical Mechanics: Theory and Experiment 2010: P04014. Available: http://dx.doi.org/10.1088/1742-5468/2010/04/P04014.

Acknowledgements
This publication was based on work supported in part by the NSF (DMS-0813677) and by award no. KUK-C1-013-4 made by King Abdullah University of Science and Technology (KAUST). PCB was also partially supported by the Royal Society-Wolfson Foundation.

Publisher
IOP Publishing

Journal
Journal of Statistical Mechanics: Theory and Experiment

DOI
10.1088/1742-5468/2010/04/P04014

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