Cargo diffusion shortens single-kinesin runs at low viscous drag

Area of Science:

• Cellular biology
• Biophysics
• Motor proteins

Background:

• Molecular motors like kinesin-1 are crucial for intracellular transport along microtubules.
• Cargo diffusion can create fluctuating mechanical loads on motors, potentially affecting their function.
• Previous experiments suggested an asymmetric sensitivity of motor run length to load direction.

Purpose of the Study:

• To investigate the impact of cargo diffusion on the run length of single kinesin-1 motors.
• To explore how viscous drag influences this diffusion-induced effect.
• To simulate intracellular transport under physiologically relevant conditions.

Main Methods:

• Utilized Monte Carlo-based simulations to model cargo transport by a single kinesin-1 motor.
• Incorporated physiologically relevant viscous drag on the cargo.
• Examined a wide range of cytoplasmic viscosities, cargo sizes, and motor velocities.

Main Results:

• Cargo diffusion was found to significantly shorten the run length of single kinesin-1 motors.
• Viscous drag counteracted the shortening effect of diffusion.
• An unexpected, non-monotonic variation in motor run length was observed as viscous drag increased.

Conclusions:

• Cargo diffusion plays a significant role in modulating single-motor transport, contrary to previous assumptions.
• The interplay between diffusion and viscous drag creates complex dynamics in motor protein function.
• This study underscores the importance of considering load-detachment kinetics and cargo diffusion in understanding single-motor behavior.