Kinesin recycling in stationary membrane tubes

Area of Science:

• Cell biology
• Biophysics
• Motor protein dynamics

Background:

• Membrane tubes are extracted by motor collections.
• These tubes interact with microtubule networks, causing pauses and direction changes.
• In vitro, membrane tubes stall despite available motors at the tip.

Purpose of the Study:

• Investigate the mechanism behind stalled membrane tubes in vitro.
• Determine how motor protein clusters form and arrive at the tube tip.
• Understand the dynamics of motor recycling and its impact on tube growth.

Main Methods:

• In vitro experiments observing membrane tube dynamics.
• Time-interval analysis of motor protein cluster arrivals at the tube tip.
• Numerical simulations of motor dynamics on microtubule networks.
• Investigating the role of cooperative binding in motor clustering.

Main Results:

• Stationary membrane tubes exhibit periodic arrivals of kinesin motor clusters at the tip.
• Motor cluster arrival intervals correlate with motor departure times, suggesting recycling.
• Cooperative binding between motors quantitatively explains observed clustering.
• A model with cooperative binding and a nucleation point predicts the recycling period.

Conclusions:

• Cooperative binding is crucial for kinesin motor clustering and recycling to membrane tube tips.
• Motor recycling dynamics, influenced by cooperative binding, regulate membrane tube growth and stalling.
• The study estimates the cooperative binding probability and concentration for this recycling phenomenon.