Diffusible Crosslinkers Generate Directed Forces in Microtubule Networks

  title={Diffusible Crosslinkers Generate Directed Forces in Microtubule Networks},
  author={Zdeněk L{\'a}nsk{\'y} and Marcus Braun and Annemarie L{\"u}decke and Michael Schlierf and Pieter Rein ten Wolde and Marcel E. Janson and Stefan Diez},

Entropic forces drive contraction of cytoskeletal networks.

Two mechanisms of cytoskeletal network remodeling that are independent of the consumption of chemical energy are reviewed, which increase filament overlap length and lead to the contraction of filament networks.

Theory of antiparallel microtubule overlap stabilization by motors and diffusible crosslinkers

A theory of two microtubules connected by motors and diffusible connectors, in different configurations that can be realized experimentally is developed, validated by stochastic simulations and used to discuss recent experimental results.

Cross-linkers at growing microtubule ends generate forces that drive actin transport

It is shown that, surprisingly, coupling via passive cross-linkers can also result in force generation, and this work predicts that growing microtubules could potentially rapidly relocate newly nucleated actin filaments to the leading edge of the cell and thus boost migration.

The mitotic crosslinking protein PRC1 acts as a mechanical dashpot to resist microtubule sliding

The results suggest that PRC1 ensembles act like a mechanical dashpot, producing significant resistance against fast motions, but minimal resistance against slow motions, allowing for the integration of diverse motor activities into a single mechanical outcome.

Measuring force generation within reconstituted microtubule bundle assemblies using optical tweezers

Kinesins and microtubule associated proteins (MAPs) are critical to sustain life, facilitating cargo transport, cell division, and motility. To interrogate the mechanistic underpinnings of their

Toward the cellular-scale simulation of motor-driven cytoskeletal assemblies

ALENS (a Living Ensemble Simulator), a novel computational framework designed to surmount the limits of conventional simulation methods, is presented, which can help elucidate how motor type, thermal fluctuations, internal stresses, and confinement determine the evolution of cytoskeletal active matter.

Theory of cytoskeletal reorganization during crosslinker-mediated mitotic spindle assembly

A torque-balance model is developed that describes cytoskeletal reorganization due to dynamic microtubule bundles, spindle-pole bodies, the nuclear envelope, and crosslinkers to predictSpindle-assembly dynamics and shows that rapid crosslinker reorganization to MT overlaps facilitatesCrosslinker-driven spindle assembly, a testable prediction for future experiments.

Two modes of PRC1-mediated mechanical resistance to kinesin-driven microtubule network disruption

The results suggest a cooperative mechanism for PRC1 accumulation when under mechanical load that leads to a unique state of enhanced resistance to filament sliding and provides insight into collective protein ensemble behavior in regulating the mechanics of spindle assembly.

Changes in microtubule overlap length regulate kinesin-14-driven microtubule sliding

It is shown in vitro that the sliding velocity of microtubules, driven by human kinesin-14, HSET, decreases when micro Tubules start to slide apart, resulting in the maintenance of finite-length microtubule overlaps, and that a spatial arrangement of micro tubules can regulate the collective action of molecular motors through local alteration of their individual interaction kinetics.



Cytoskeletal Cross-linking and Bundling in Motor-Independent Contraction

Long tethers provide high-force coupling of the Dam1 ring to shortening microtubules

This work reports that, when Dam1 is linked to a bead cargo by elongated protein tethers, the maximum force transmitted from a disassembling microtubule increases sixfold compared with a short tether, suggesting that a tethered Dam1 ring comprises the main force-bearing unit of the native attachment.

Crosslinkers and Motors Organize Dynamic Microtubules to Form Stable Bipolar Arrays in Fission Yeast

The depolymerizing kinesin MCAK uses lattice diffusion to rapidly target microtubule ends

It is shown that MCAK moves along the microtubule lattice in a one-dimensional (1D) random walk, corresponding to a “reduction in dimensionality” that has been proposed as the search strategy by which DNA enzymes find specific binding sites.

The Dam1 kinetochore complex harnesses microtubule dynamics to produce force and movement.

An in vitro motility assay is developed where beads coated with pure recombinant Dam1 complex were bound to the tips of individual dynamic MTs, demonstrating how the Dam1complex may contribute directly to MT-driven chromosome movement.

Individual dimers of the mitotic kinesin motor Eg5 step processively and support substantial loads in vitro

It is found that the velocity of Eg5 was slower and less sensitive to external load than that of conventional kinesin, possibly reflecting the distinct demands of spindle assembly as compared with vesicle transport.

Adaptive braking by Ase1 prevents overlapping microtubules from sliding completely apart

It is shown that Ase1, a member of the conserved MAP65/PRC1 family of microtubule-bundling proteins, enables the formation of stable antiparallel overlaps through adaptive braking of Kinesin-14-driven micro Tubule–microtubule sliding.

The force exerted by a single kinesin molecule against a viscous load.