Transport properties of melanosomes along microtubules interpreted by a tug-of-war model with loose mechanical coupling

PLoS One. 2012;7(8):e43599. doi: 10.1371/journal.pone.0043599. Epub 2012 Aug 30.

Abstract

In this work, we explored theoretically the transport of organelles driven along microtubules by molecular motors of opposed polarities using a stochastic model that considers a Langevin dynamics for the cargo, independent cargo-motor linkers and stepping motion for the motors. It has been recently proposed that the stiffness of the motor plays an important role when multiple motors collectively transport a cargo. Therefore, we considered in our model the recently reported values for the stiffness of the cargo-motor linker determined in living cells (∼0.01 pN/nm,) which is significantly lower than the motor stiffness obtained in in vitro assays and used in previous studies. Our model could reproduce the multimodal velocity distributions and typical trajectory characteristics including the properties of the reversions in the overall direction of motion observed during melanosome transport along microtubules in Xenopus laevis melanophores. Moreover, we explored the contribution of the different motility states of the cargo-motor system to the different modes of the velocity distributions and could identify the microscopic mechanisms of transport leading to trajectories compatible with those observed in living cells. Finally, by changing the attachment and detachment rates, the model could reproduce the different velocity distributions observed during melanosome transport along microtubules in Xenopus laevis melanophores stimulated for aggregation and dispersion. Our analysis suggests that active tug-of-war processes with loose mechanical coupling can account for several aspects of cargo transport along microtubules in living cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Biomechanical Phenomena
  • Kinetics
  • Mechanical Phenomena*
  • Melanosomes / metabolism*
  • Microtubules / metabolism*
  • Models, Biological*
  • Molecular Motor Proteins / metabolism
  • Movement
  • Stochastic Processes
  • Xenopus laevis

Substances

  • Molecular Motor Proteins

Grants and funding

This research was supported by ANPCyT -Agencia Nacional de Promoción Científica y Tecnológica (under grant number PICT 2008-1104), CONICET -Consejo Nacional de Investigaciones Científicas y Técnicas (under grant number PIP 11220080100076) and CNEA -Comisión Nacional de Energía Atómica, all Argentinean agencies. The authors are members of CONICET, Argentina. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.