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Title: Kinesin‐Driven De‐Mixing of Cytoskeleton Composites Drives Emergent Mechanical Properties
Abstract The cytoskeleton is an active composite of filamentous proteins that dictates diverse mechanical properties and processes in eukaryotic cells by generating forces and autonomously restructuring itself. Enzymatic motors that act on the comprising filaments play key roles in this activity, driving spatiotemporally heterogeneous mechanical responses that are critical to cellular multifunctionality, but also render mechanical characterization challenging. Here, we couple optical tweezers microrheology and fluorescence microscopy with simulations and mathematical modeling to robustly characterize the mechanics of active composites of actin filaments and microtubules restructured by kinesin motors. It is discovered that composites exhibit a rich ensemble of force response behaviors–elastic, yielding, and stiffening–with their propensity and properties tuned by motor concentration and strain rate. Moreover, intermediate kinesin concentrations elicit emergent mechanical stiffness and resistance while higher and lower concentrations exhibit softer, more viscous dissipation. It is further shown that composites transition from well‐mixed interpenetrating double‐networks of actin and microtubules to de‐mixed states of microtubule‐rich aggregates surrounded by relatively undisturbed actin phases. It is this de‐mixing that leads to the emergent mechanical response, offering an alternate route that composites can leverage to achieve enhanced stiffness through coupling of structure and mechanics.  more » « less
Award ID(s):
2118497 2203791 2119663 2118403
PAR ID:
10646036
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Macromolecular Rapid Communications
Volume:
46
Issue:
14
ISSN:
1022-1336
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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