Memoryless self-reinforcing directionality in endosomal active transport within living cells

Area of Science:

• Biophysics
• Active Matter Physics
• Cell Biology

Background:

• Active biological systems, from microbes to humans, exhibit complex movement patterns.
• Stochastic motions like truncated Lévy walks, characterized by intermittent long jumps, are observed in various biological contexts.
• The functional advantages of Lévy walks over Brownian motion in search and transport are debated but suggest potential applications in engineered systems.

Purpose of the Study:

• To investigate the emergence of truncated Lévy walks in active matter systems.
• To understand the underlying mechanisms driving the self-organization of movement patterns in intracellular trafficking.
• To explore the potential for engineering active materials with enhanced transport properties.

Main Methods:

• Experimental observation of intracellular trafficking dynamics.
• Analysis of step-size distributions and persistence in movement.
• Development and application of a molecular model to quantitatively fit experimental data.

Main Results:

• Brownian-like steps were observed to self-organize into truncated Lévy walks in an active matter system.
• A positive feedback mechanism was identified, leading to increased directional persistence with distance traveled.
• A molecular model involving slow fluctuations in propelling forces accurately reproduced the experimental findings.

Conclusions:

• Intracellular trafficking naturally exhibits truncated Lévy walk dynamics, suggesting functional advantages for biological transport.
• The findings provide insights into the self-organization of active matter and offer design principles for creating efficient transport in engineered active materials.