Actomyosin dynamics drive local membrane component organization in an in vitro active composite layer

Area of Science:

• Cell biology
• Biophysics
• Soft matter physics

Background:

• Cell surface organization is crucial for cellular functions like signaling and transport.
• The cell surface is modeled as an active composite of a lipid bilayer and actomyosin.
• Actomyosin dynamics play a key role in organizing membrane proteins and lipids.

Purpose of the Study:

• To reconstitute an in vitro model of the cell surface active composite.
• To investigate how actomyosin dynamics influence membrane organization.
• To understand the physical basis of active membrane organization.

Main Methods:

• Reconstitution of a fluid lipid bilayer coupled to actin filaments and myosin motors.
• Observation of phase transitions in the actomyosin network upon ATP consumption.
• Analysis of membrane component clustering and domain dynamics driven by actomyosin.

Main Results:

• The reconstituted system exhibits distinct actomyosin organization phases (bundles, apolar asters, polar asters) dependent on actin/myosin ratios and concentrations.
• Actomyosin network advection drives transient clustering of membrane components.
• Active actomyosin remodeling induces fluctuations in coupled membrane components and affects phase-segregating domains.

Conclusions:

• The active composite model provides a fundamental basis for understanding cell surface organization.
• Actomyosin dynamics locally drive membrane composition and organization.
• This in vitro system is relevant for studying active membrane organization and its role in cellular processes.