Multiscale modeling and simulation of microtubule/motor protein assemblies

Abstract

Microtubules and motor proteins self organize into biologically important assemblies including the mitotic spindle and the centrosomal microtubule array. Outside of cells, microtubule-motor mixtures can form novel active liquid-crystalline materials driven out of equilibrium by ATP-consuming motor proteins. Microscopic motor activity causes polarity-dependent interactions between motor proteins and microtubules, but how these interactions yield such larger-scale dynamical behavior such as complex flows and defect dynamics is not well understood. We develop a multiscale theory for microtubule-motor systems in which Brownian dynamics simulations of polar microtubules driven by motors are used to study microscopic organization and stresses created by motor-mediated microtubule interactions. We identify polarity-sorting and crosslink tether relaxation as two polar-specific sources of active destabilizing stress. We then develop a continuum Doi-Onsager model that captures polarity sorting and the hydrodynamic flows generated by these polar-specific active stresses. In simulations of active nematic flows on immersed surfaces, the active stresses drive turbulent flow dynamics and continuous generation and annihilation of disclination defects. The dynamics follow from two instabilities, and accounting for the immersed nature of the experiment yields unambiguous characteristic length and time scales. When turning off the hydrodynamics in the Doi-Onsager model, we capture formation of polar lanes as observed in the Brownian dynamics simulation.

arXiv admin note: substantial text overlap with arXiv:1401.8059

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Cited by in corpus (9)

• Analytical structure, dynamics, and coarse-graining of a kinetic model of an active fluid
• Contributions of microtubule dynamic instability and rotational diffusion to kinetochore capture
• Towards the cellular-scale simulation of motor-driven cytoskeletal assemblies
• Connecting macroscopic dynamics with microscopic properties in active microtubule network contraction
• How crosslink numbers shape the large-scale physics of cytoskeletal materials
• Supramolecular assemblies in active motor-filament systems: micelles, bilayers, and foams
• Filamentous Active Matter: Band Formation, Bending, Buckling, and Defects
• Flow coupling between active and passive fluids across water-oil interfaces
• Machine Learning Forecasting of Active Nematics