Active condensation of filaments under spatial confinement

Area of Science:

• Biophysics
• Cell Biology
• Soft Matter Physics

Background:

• Living cells feature crowded interiors where cytoskeletal networks self-assemble.
• Spatial confinement by cellular structures influences cytoskeletal network morphology.
• Active condensation of filaments by motor proteins is crucial for cellular functions.

Purpose of the Study:

• To investigate how varying confinement geometries affect active cytoskeletal condensates.
• To explore the role of crosslinking motor proteins and end-pausing dynamics in condensate formation.
• To understand the self-organization principles governing cytoskeletal assembly in constrained environments.

Main Methods:

• Computational simulations of filament and crosslinking motor protein systems.
• Modeling spatial confinement using spherical, cylindrical, and planar boundaries.
• Analysis of condensate dynamics, morphology, and phase behavior.

Main Results:

• Confinement lengthscale significantly alters condensate dynamics and morphology.
• Specific geometries induce distinct self-organized structures: asters, bilayers, and flattened asters.
• End-pausing motor activity is critical for forming aster-like condensates, while non-end-pausing motors yield disordered or bundled states.

Conclusions:

• Geometric confinement is a key regulator of active cytoskeletal self-organization.
• The behavior of crosslinking motor proteins, particularly end-pausing, dictates emergent condensate structures.
• These findings provide insights into how cellular architecture controls cytoskeletal organization and function.